LinuxLists.cc - KASAN: use-after-free Read in device_release_driver

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Subject: Re: KASAN: use-after-free Read in device_release_driver_internal

On Tue, Jul 23, 2019 at 4:28 PM syzbot
<[email protected]> wrote:
>
> Hello,
>
> syzbot found the following crash on:
>
> HEAD commit: 6a3599ce usb-fuzzer: main usb gadget fuzzer driver
> git tree: https://github.com/google/kasan.git usb-fuzzer
> console output: https://syzkaller.appspot.com/x/log.txt?x=13f640cc600000
> kernel config: https://syzkaller.appspot.com/x/.config?x=700ca426ab83faae
> dashboard link: https://syzkaller.appspot.com/bug?extid=1b2449b7b5dc240d107a
> compiler: gcc (GCC) 9.0.0 20181231 (experimental)
> syz repro: https://syzkaller.appspot.com/x/repro.syz?x=116ce31fa00000
> C reproducer: https://syzkaller.appspot.com/x/repro.c?x=1022f694600000
>
> IMPORTANT: if you fix the bug, please add the following tag to the commit:
> Reported-by: [email protected]
>
> usb 1-1: USB disconnect, device number 2
> ==================================================================
> BUG: KASAN: use-after-free in __lock_acquire+0x3a5d/0x5340
> /kernel/locking/lockdep.c:3665
> Read of size 8 at addr ffff8881cfc4ef90 by task kworker/0:2/108
>
> CPU: 0 PID: 108 Comm: kworker/0:2 Not tainted 5.2.0-rc6+ #15
> Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS
> Google 01/01/2011
> Workqueue: usb_hub_wq hub_event
> Call Trace:
> __dump_stack /lib/dump_stack.c:77 [inline]
> dump_stack+0xca/0x13e /lib/dump_stack.c:113
> print_address_description+0x67/0x231 /mm/kasan/report.c:188
> __kasan_report.cold+0x1a/0x32 /mm/kasan/report.c:317
> kasan_report+0xe/0x20 /mm/kasan/common.c:614
> __lock_acquire+0x3a5d/0x5340 /kernel/locking/lockdep.c:3665
> lock_acquire+0x100/0x2b0 /kernel/locking/lockdep.c:4303
> __mutex_lock_common /kernel/locking/mutex.c:926 [inline]
> __mutex_lock+0xf9/0x12b0 /kernel/locking/mutex.c:1073
> device_release_driver_internal+0x23/0x4c0 /drivers/base/dd.c:1109
> bus_remove_device+0x2dc/0x4a0 /drivers/base/bus.c:556
> device_del+0x460/0xb80 /drivers/base/core.c:2274
> usb_disable_device+0x211/0x690 /drivers/usb/core/message.c:1237
> usb_disconnect+0x284/0x830 /drivers/usb/core/hub.c:2199
> hub_port_connect /drivers/usb/core/hub.c:4949 [inline]
> hub_port_connect_change /drivers/usb/core/hub.c:5213 [inline]
> port_event /drivers/usb/core/hub.c:5359 [inline]
> hub_event+0x13bd/0x3550 /drivers/usb/core/hub.c:5441
> process_one_work+0x905/0x1570 /kernel/workqueue.c:2269
> worker_thread+0x96/0xe20 /kernel/workqueue.c:2415
> kthread+0x30b/0x410 /kernel/kthread.c:255
> ret_from_fork+0x24/0x30 /arch/x86/entry/entry_64.S:352
>
> Allocated by task 88:
> save_stack+0x1b/0x80 /mm/kasan/common.c:71
> set_track /mm/kasan/common.c:79 [inline]
> __kasan_kmalloc /mm/kasan/common.c:489 [inline]
> __kasan_kmalloc.constprop.0+0xbf/0xd0 /mm/kasan/common.c:462
> kmalloc /./include/linux/slab.h:547 [inline]
> kzalloc /./include/linux/slab.h:742 [inline]
> usb_set_configuration+0x2c4/0x1670 /drivers/usb/core/message.c:1846
> generic_probe+0x9d/0xd5 /drivers/usb/core/generic.c:210
> usb_probe_device+0x99/0x100 /drivers/usb/core/driver.c:266
> really_probe+0x281/0x660 /drivers/base/dd.c:509
> driver_probe_device+0x104/0x210 /drivers/base/dd.c:670
> __device_attach_driver+0x1c2/0x220 /drivers/base/dd.c:777
> bus_for_each_drv+0x15c/0x1e0 /drivers/base/bus.c:454
> __device_attach+0x217/0x360 /drivers/base/dd.c:843
> bus_probe_device+0x1e4/0x290 /drivers/base/bus.c:514
> device_add+0xae6/0x16f0 /drivers/base/core.c:2111
> usb_new_device.cold+0x6a4/0xe61 /drivers/usb/core/hub.c:2536
> hub_port_connect /drivers/usb/core/hub.c:5098 [inline]
> hub_port_connect_change /drivers/usb/core/hub.c:5213 [inline]
> port_event /drivers/usb/core/hub.c:5359 [inline]
> hub_event+0x1abd/0x3550 /drivers/usb/core/hub.c:5441
> process_one_work+0x905/0x1570 /kernel/workqueue.c:2269
> worker_thread+0x96/0xe20 /kernel/workqueue.c:2415
> kthread+0x30b/0x410 /kernel/kthread.c:255
> ret_from_fork+0x24/0x30 /arch/x86/entry/entry_64.S:352
>
> Freed by task 108:
> save_stack+0x1b/0x80 /mm/kasan/common.c:71
> set_track /mm/kasan/common.c:79 [inline]
> __kasan_slab_free+0x130/0x180 /mm/kasan/common.c:451
> slab_free_hook /mm/slub.c:1421 [inline]
> slab_free_freelist_hook /mm/slub.c:1448 [inline]
> slab_free /mm/slub.c:2994 [inline]
> kfree+0xd7/0x280 /mm/slub.c:3949
> device_release+0x71/0x200 /drivers/base/core.c:1064
> kobject_cleanup /lib/kobject.c:691 [inline]
> kobject_release /lib/kobject.c:720 [inline]
> kref_put /./include/linux/kref.h:65 [inline]
> kobject_put+0x171/0x280 /lib/kobject.c:737
> put_device+0x1b/0x30 /drivers/base/core.c:2210
> klist_put+0xce/0x170 /lib/klist.c:221
> bus_remove_device+0x3a4/0x4a0 /drivers/base/bus.c:552
> device_del+0x460/0xb80 /drivers/base/core.c:2274
> usb_disable_device+0x211/0x690 /drivers/usb/core/message.c:1237
> usb_disconnect+0x284/0x830 /drivers/usb/core/hub.c:2199
> hub_port_connect /drivers/usb/core/hub.c:4949 [inline]
> hub_port_connect_change /drivers/usb/core/hub.c:5213 [inline]
> port_event /drivers/usb/core/hub.c:5359 [inline]
> hub_event+0x13bd/0x3550 /drivers/usb/core/hub.c:5441
> process_one_work+0x905/0x1570 /kernel/workqueue.c:2269
> worker_thread+0x96/0xe20 /kernel/workqueue.c:2415
> kthread+0x30b/0x410 /kernel/kthread.c:255
> ret_from_fork+0x24/0x30 /arch/x86/entry/entry_64.S:352
>
> The buggy address belongs to the object at ffff8881cfc4ee80
> which belongs to the cache kmalloc-2k of size 2048
> The buggy address is located 272 bytes inside of
> 2048-byte region [ffff8881cfc4ee80, ffff8881cfc4f680)
> The buggy address belongs to the page:
> page:ffffea00073f1200 refcount:1 mapcount:0 mapping:ffff8881dac02800
> index:0x0 compound_mapcount: 0
> flags: 0x200000000010200(slab|head)
> raw: 0200000000010200 dead000000000100 dead000000000200 ffff8881dac02800
> raw: 0000000000000000 00000000000f000f 00000001ffffffff 0000000000000000
> page dumped because: kasan: bad access detected
>
> Memory state around the buggy address:
> ffff8881cfc4ee80: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
> ffff8881cfc4ef00: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
> > ffff8881cfc4ef80: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
> ^
> ffff8881cfc4f000: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
> ffff8881cfc4f080: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
> ==================================================================

Hi Alan,

Could you take a look at this report? This looks like some kind of bug
in USB core code, but I can't really figure out what's going on here.

Thanks!

>
>
> ---
> This bug is generated by a bot. It may contain errors.
> See https://goo.gl/tpsmEJ for more information about syzbot.
> syzbot engineers can be reached at [email protected].
>
> syzbot will keep track of this bug report. See:
> https://goo.gl/tpsmEJ#status for how to communicate with syzbot.
> syzbot can test patches for this bug, for details see:
> https://goo.gl/tpsmEJ#testing-patches

2019-08-01 23:46:44

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Subject: Re: KASAN: use-after-free Read in device_release_driver_internal

On Thu, 1 Aug 2019, Andrey Konovalov wrote:

> On Tue, Jul 23, 2019 at 4:28 PM syzbot
> <[email protected]> wrote:
> >
> > Hello,
> >
> > syzbot found the following crash on:
> >
> > HEAD commit: 6a3599ce usb-fuzzer: main usb gadget fuzzer driver
> > git tree: https://github.com/google/kasan.git usb-fuzzer
> > console output: https://syzkaller.appspot.com/x/log.txt?x=13f640cc600000
> > kernel config: https://syzkaller.appspot.com/x/.config?x=700ca426ab83faae
> > dashboard link: https://syzkaller.appspot.com/bug?extid=1b2449b7b5dc240d107a
> > compiler: gcc (GCC) 9.0.0 20181231 (experimental)
> > syz repro: https://syzkaller.appspot.com/x/repro.syz?x=116ce31fa00000
> > C reproducer: https://syzkaller.appspot.com/x/repro.c?x=1022f694600000
> >
> > IMPORTANT: if you fix the bug, please add the following tag to the commit:
> > Reported-by: [email protected]
> >
> > usb 1-1: USB disconnect, device number 2
> > ==================================================================
> > BUG: KASAN: use-after-free in __lock_acquire+0x3a5d/0x5340
> > /kernel/locking/lockdep.c:3665
> > Read of size 8 at addr ffff8881cfc4ef90 by task kworker/0:2/108
> >
> > CPU: 0 PID: 108 Comm: kworker/0:2 Not tainted 5.2.0-rc6+ #15
> > Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS
> > Google 01/01/2011
> > Workqueue: usb_hub_wq hub_event
> > Call Trace:
> > __dump_stack /lib/dump_stack.c:77 [inline]
> > dump_stack+0xca/0x13e /lib/dump_stack.c:113
> > print_address_description+0x67/0x231 /mm/kasan/report.c:188
> > __kasan_report.cold+0x1a/0x32 /mm/kasan/report.c:317
> > kasan_report+0xe/0x20 /mm/kasan/common.c:614
> > __lock_acquire+0x3a5d/0x5340 /kernel/locking/lockdep.c:3665
> > lock_acquire+0x100/0x2b0 /kernel/locking/lockdep.c:4303
> > __mutex_lock_common /kernel/locking/mutex.c:926 [inline]
> > __mutex_lock+0xf9/0x12b0 /kernel/locking/mutex.c:1073
> > device_release_driver_internal+0x23/0x4c0 /drivers/base/dd.c:1109
> > bus_remove_device+0x2dc/0x4a0 /drivers/base/bus.c:556
> > device_del+0x460/0xb80 /drivers/base/core.c:2274
> > usb_disable_device+0x211/0x690 /drivers/usb/core/message.c:1237
> > usb_disconnect+0x284/0x830 /drivers/usb/core/hub.c:2199
> > hub_port_connect /drivers/usb/core/hub.c:4949 [inline]
> > hub_port_connect_change /drivers/usb/core/hub.c:5213 [inline]
> > port_event /drivers/usb/core/hub.c:5359 [inline]
> > hub_event+0x13bd/0x3550 /drivers/usb/core/hub.c:5441
> > process_one_work+0x905/0x1570 /kernel/workqueue.c:2269
> > worker_thread+0x96/0xe20 /kernel/workqueue.c:2415
> > kthread+0x30b/0x410 /kernel/kthread.c:255
> > ret_from_fork+0x24/0x30 /arch/x86/entry/entry_64.S:352
> >
> > Allocated by task 88:
> > save_stack+0x1b/0x80 /mm/kasan/common.c:71
> > set_track /mm/kasan/common.c:79 [inline]
> > __kasan_kmalloc /mm/kasan/common.c:489 [inline]
> > __kasan_kmalloc.constprop.0+0xbf/0xd0 /mm/kasan/common.c:462
> > kmalloc /./include/linux/slab.h:547 [inline]
> > kzalloc /./include/linux/slab.h:742 [inline]
> > usb_set_configuration+0x2c4/0x1670 /drivers/usb/core/message.c:1846
> > generic_probe+0x9d/0xd5 /drivers/usb/core/generic.c:210
> > usb_probe_device+0x99/0x100 /drivers/usb/core/driver.c:266
> > really_probe+0x281/0x660 /drivers/base/dd.c:509
> > driver_probe_device+0x104/0x210 /drivers/base/dd.c:670
> > __device_attach_driver+0x1c2/0x220 /drivers/base/dd.c:777
> > bus_for_each_drv+0x15c/0x1e0 /drivers/base/bus.c:454
> > __device_attach+0x217/0x360 /drivers/base/dd.c:843
> > bus_probe_device+0x1e4/0x290 /drivers/base/bus.c:514
> > device_add+0xae6/0x16f0 /drivers/base/core.c:2111
> > usb_new_device.cold+0x6a4/0xe61 /drivers/usb/core/hub.c:2536
> > hub_port_connect /drivers/usb/core/hub.c:5098 [inline]
> > hub_port_connect_change /drivers/usb/core/hub.c:5213 [inline]
> > port_event /drivers/usb/core/hub.c:5359 [inline]
> > hub_event+0x1abd/0x3550 /drivers/usb/core/hub.c:5441
> > process_one_work+0x905/0x1570 /kernel/workqueue.c:2269
> > worker_thread+0x96/0xe20 /kernel/workqueue.c:2415
> > kthread+0x30b/0x410 /kernel/kthread.c:255
> > ret_from_fork+0x24/0x30 /arch/x86/entry/entry_64.S:352
> >
> > Freed by task 108:
> > save_stack+0x1b/0x80 /mm/kasan/common.c:71
> > set_track /mm/kasan/common.c:79 [inline]
> > __kasan_slab_free+0x130/0x180 /mm/kasan/common.c:451
> > slab_free_hook /mm/slub.c:1421 [inline]
> > slab_free_freelist_hook /mm/slub.c:1448 [inline]
> > slab_free /mm/slub.c:2994 [inline]
> > kfree+0xd7/0x280 /mm/slub.c:3949
> > device_release+0x71/0x200 /drivers/base/core.c:1064
> > kobject_cleanup /lib/kobject.c:691 [inline]
> > kobject_release /lib/kobject.c:720 [inline]
> > kref_put /./include/linux/kref.h:65 [inline]
> > kobject_put+0x171/0x280 /lib/kobject.c:737
> > put_device+0x1b/0x30 /drivers/base/core.c:2210
> > klist_put+0xce/0x170 /lib/klist.c:221
> > bus_remove_device+0x3a4/0x4a0 /drivers/base/bus.c:552
> > device_del+0x460/0xb80 /drivers/base/core.c:2274
> > usb_disable_device+0x211/0x690 /drivers/usb/core/message.c:1237
> > usb_disconnect+0x284/0x830 /drivers/usb/core/hub.c:2199
> > hub_port_connect /drivers/usb/core/hub.c:4949 [inline]
> > hub_port_connect_change /drivers/usb/core/hub.c:5213 [inline]
> > port_event /drivers/usb/core/hub.c:5359 [inline]
> > hub_event+0x13bd/0x3550 /drivers/usb/core/hub.c:5441
> > process_one_work+0x905/0x1570 /kernel/workqueue.c:2269
> > worker_thread+0x96/0xe20 /kernel/workqueue.c:2415
> > kthread+0x30b/0x410 /kernel/kthread.c:255
> > ret_from_fork+0x24/0x30 /arch/x86/entry/entry_64.S:352
> >
> > The buggy address belongs to the object at ffff8881cfc4ee80
> > which belongs to the cache kmalloc-2k of size 2048
> > The buggy address is located 272 bytes inside of
> > 2048-byte region [ffff8881cfc4ee80, ffff8881cfc4f680)
> > The buggy address belongs to the page:
> > page:ffffea00073f1200 refcount:1 mapcount:0 mapping:ffff8881dac02800
> > index:0x0 compound_mapcount: 0
> > flags: 0x200000000010200(slab|head)
> > raw: 0200000000010200 dead000000000100 dead000000000200 ffff8881dac02800
> > raw: 0000000000000000 00000000000f000f 00000001ffffffff 0000000000000000
> > page dumped because: kasan: bad access detected
> >
> > Memory state around the buggy address:
> > ffff8881cfc4ee80: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
> > ffff8881cfc4ef00: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
> > > ffff8881cfc4ef80: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
> > ^
> > ffff8881cfc4f000: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
> > ffff8881cfc4f080: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
> > ==================================================================
>
> Hi Alan,
>
> Could you take a look at this report? This looks like some kind of bug
> in USB core code, but I can't really figure out what's going on here.

I think this must be caused by an unbalanced refcount. That is,
something must drop one more reference to the device than it takes.
That would explain why the invalid access occurs inside a single
bus_remove_device() call, between the klist_del() and
device_release_driver().

The kernel log indicates that the device was probed by rndis_wlan,
rndis_host, and cdc_acm, all of which got errors because of the
device's bogus descriptors. Probably one of them is messing up the
refcount.

Hard to say which or where, though.

Alan Stern

2019-08-06 12:37:59

[permalink] [raw]

Subject: Re: KASAN: use-after-free Read in device_release_driver_internal

Am Donnerstag, den 01.08.2019, 14:47 -0400 schrieb Alan Stern:
>
> I think this must be caused by an unbalanced refcount. That is,
> something must drop one more reference to the device than it takes.
> That would explain why the invalid access occurs inside a single
> bus_remove_device() call, between the klist_del() and
> device_release_driver().
>
> The kernel log indicates that the device was probed by rndis_wlan,
> rndis_host, and cdc_acm, all of which got errors because of the
> device's bogus descriptors. Probably one of them is messing up the
> refcount.

Hi,

you made me look at cdc-acm. I suspect

cae2bc768d176bfbdad7035bbcc3cdc973eb7984 ("usb: cdc-acm: Decrement tty port's refcount if probe() fail")

is buggy decrementing the refcount on the interface in destroy()
even before the refcount is increased.

Unfortunately I cannot tell from the bug report how many and which
interfaces the emulated test device has. Hence it is unclear to me,
when exactly probe() would fail cdc-acm.

If you agree. I am attaching a putative fix.

Regards
Oliver

Attachments:

0001-usb-cdc-acm-make-sure-a-refcount-is-taken-early-enou.patch (1.71 kB)

2019-08-06 12:52:25

[permalink] [raw]

Subject: Re: KASAN: use-after-free Read in device_release_driver_internal

On Tue, Aug 6, 2019 at 2:36 PM Oliver Neukum <[email protected]> wrote:
>
> Am Donnerstag, den 01.08.2019, 14:47 -0400 schrieb Alan Stern:
> >
> > I think this must be caused by an unbalanced refcount. That is,
> > something must drop one more reference to the device than it takes.
> > That would explain why the invalid access occurs inside a single
> > bus_remove_device() call, between the klist_del() and
> > device_release_driver().
> >
> > The kernel log indicates that the device was probed by rndis_wlan,
> > rndis_host, and cdc_acm, all of which got errors because of the
> > device's bogus descriptors. Probably one of them is messing up the
> > refcount.
>
> Hi,
>
> you made me look at cdc-acm. I suspect
>
> cae2bc768d176bfbdad7035bbcc3cdc973eb7984 ("usb: cdc-acm: Decrement tty port's refcount if probe() fail")
>
> is buggy decrementing the refcount on the interface in destroy()
> even before the refcount is increased.
>
> Unfortunately I cannot tell from the bug report how many and which
> interfaces the emulated test device has. Hence it is unclear to me,
> when exactly probe() would fail cdc-acm.
>
> If you agree. I am attaching a putative fix.

Let's see if it fixes the issue.

#syz fix: https://github.com/google/kasan.git 6a3599ce

>
> Regards
> Oliver

Attachments:

0001-usb-cdc-acm-make-sure-a-refcount-is-taken-early-enou.patch (1.71 kB)

2019-08-06 14:22:11

[permalink] [raw]

Subject: Re: KASAN: use-after-free Read in device_release_driver_internal

On Tue, 6 Aug 2019, Oliver Neukum wrote:

> Am Donnerstag, den 01.08.2019, 14:47 -0400 schrieb Alan Stern:
> >
> > I think this must be caused by an unbalanced refcount. That is,
> > something must drop one more reference to the device than it takes.
> > That would explain why the invalid access occurs inside a single
> > bus_remove_device() call, between the klist_del() and
> > device_release_driver().
> >
> > The kernel log indicates that the device was probed by rndis_wlan,
> > rndis_host, and cdc_acm, all of which got errors because of the
> > device's bogus descriptors. Probably one of them is messing up the
> > refcount.
>
> Hi,
>
> you made me look at cdc-acm. I suspect
>
> cae2bc768d176bfbdad7035bbcc3cdc973eb7984 ("usb: cdc-acm: Decrement tty port's refcount if probe() fail")
>
> is buggy decrementing the refcount on the interface in destroy()
> even before the refcount is increased.
>
> Unfortunately I cannot tell from the bug report how many and which
> interfaces the emulated test device has. Hence it is unclear to me,
> when exactly probe() would fail cdc-acm.

Only one interface (numbered 234!).

> If you agree. I am attaching a putative fix.

Your patch adds a line saying:

> + usb_get_intf(acm->control); /* undone in destroy() */

but I don't see any destroy() function in that source file. Did you
mean acm_port_destruct()?

In any case, I don't know if this missing "get" would cause the
problem, but it might well.

Alan Stern

2019-08-06 14:27:13

[permalink] [raw]

Subject: Re: KASAN: use-after-free Read in device_release_driver_internal

Am Dienstag, den 06.08.2019, 10:19 -0400 schrieb Alan Stern:
> On Tue, 6 Aug 2019, Oliver Neukum wrote:
>
> > Am Donnerstag, den 01.08.2019, 14:47 -0400 schrieb Alan Stern:
> > >
> > > I think this must be caused by an unbalanced refcount. That is,
> > > something must drop one more reference to the device than it takes.
> > > That would explain why the invalid access occurs inside a single
> > > bus_remove_device() call, between the klist_del() and
> > > device_release_driver().
> > >
> > > The kernel log indicates that the device was probed by rndis_wlan,
> > > rndis_host, and cdc_acm, all of which got errors because of the
> > > device's bogus descriptors. Probably one of them is messing up the
> > > refcount.
> >
> > Hi,
> >
> > you made me look at cdc-acm. I suspect
> >
> > cae2bc768d176bfbdad7035bbcc3cdc973eb7984 ("usb: cdc-acm: Decrement tty port's refcount if probe() fail")
> >
> > is buggy decrementing the refcount on the interface in destroy()
> > even before the refcount is increased.
> >
> > Unfortunately I cannot tell from the bug report how many and which
> > interfaces the emulated test device has. Hence it is unclear to me,
> > when exactly probe() would fail cdc-acm.
>
> Only one interface (numbered 234!).

Yes. cdc-acm went into the look_for_collapsed_interface code path.
But I cannot tell whether it proceeded to made_compressed_probe

(Yes, I know the code makes extensive use of "goto")

> > If you agree. I am attaching a putative fix.
>
> Your patch adds a line saying:
>
> > + usb_get_intf(acm->control); /* undone in destroy() */
>
> but I don't see any destroy() function in that source file. Did you
> mean acm_port_destruct()?

Yes, sorry

> In any case, I don't know if this missing "get" would cause the
> problem, but it might well.

Then let's wait for the result.

Regards
Oliver

2019-08-06 15:35:25

[permalink] [raw]

Subject: Re: KASAN: use-after-free Read in device_release_driver_internal

Am Dienstag, den 06.08.2019, 10:19 -0400 schrieb Alan Stern:
> In any case, I don't know if this missing "get" would cause the
> problem, but it might well.

Hi,

upon further thought, this should be automated. Checking for
refcount leaks is KASAN's job. In particular, refcounts
should not

* decrease in probe()
* increase in disconnect()
* change in case probe() fails

Regards
Oliver

2019-08-07 13:39:48

[permalink] [raw]

Subject: Re: KASAN: use-after-free Read in device_release_driver_internal

Am Dienstag, den 06.08.2019, 14:50 +0200 schrieb Andrey Konovalov:
> On Tue, Aug 6, 2019 at 2:36 PM Oliver Neukum <[email protected]> wrote:
> >
> > Am Donnerstag, den 01.08.2019, 14:47 -0400 schrieb Alan Stern:
> > >
> > > I think this must be caused by an unbalanced refcount. That is,
> > > something must drop one more reference to the device than it takes.
> > > That would explain why the invalid access occurs inside a single
> > > bus_remove_device() call, between the klist_del() and
> > > device_release_driver().
> > >
> > > The kernel log indicates that the device was probed by rndis_wlan,
> > > rndis_host, and cdc_acm, all of which got errors because of the
> > > device's bogus descriptors. Probably one of them is messing up the
> > > refcount.
> >
> > Hi,
> >
> > you made me look at cdc-acm. I suspect
> >
> > cae2bc768d176bfbdad7035bbcc3cdc973eb7984 ("usb: cdc-acm: Decrement tty port's refcount if probe() fail")
> >
> > is buggy decrementing the refcount on the interface in destroy()
> > even before the refcount is increased.
> >
> > Unfortunately I cannot tell from the bug report how many and which
> > interfaces the emulated test device has. Hence it is unclear to me,
> > when exactly probe() would fail cdc-acm.
> >
> > If you agree. I am attaching a putative fix.
>
> Let's see if it fixes the issue.
>
> #syz fix: https://github.com/google/kasan.git 6a3599ce

Hi,

did this ever produce a result? I saw none.

Regards
Oliver

2019-08-07 13:45:35

[permalink] [raw]

Subject: Re: KASAN: use-after-free Read in device_release_driver_internal

On Wed, Aug 7, 2019 at 3:38 PM Oliver Neukum <[email protected]> wrote:
>
> Am Dienstag, den 06.08.2019, 14:50 +0200 schrieb Andrey Konovalov:
> > On Tue, Aug 6, 2019 at 2:36 PM Oliver Neukum <[email protected]> wrote:
> > >
> > > Am Donnerstag, den 01.08.2019, 14:47 -0400 schrieb Alan Stern:
> > > >
> > > > I think this must be caused by an unbalanced refcount. That is,
> > > > something must drop one more reference to the device than it takes.
> > > > That would explain why the invalid access occurs inside a single
> > > > bus_remove_device() call, between the klist_del() and
> > > > device_release_driver().
> > > >
> > > > The kernel log indicates that the device was probed by rndis_wlan,
> > > > rndis_host, and cdc_acm, all of which got errors because of the
> > > > device's bogus descriptors. Probably one of them is messing up the
> > > > refcount.
> > >
> > > Hi,
> > >
> > > you made me look at cdc-acm. I suspect
> > >
> > > cae2bc768d176bfbdad7035bbcc3cdc973eb7984 ("usb: cdc-acm: Decrement tty port's refcount if probe() fail")
> > >
> > > is buggy decrementing the refcount on the interface in destroy()
> > > even before the refcount is increased.
> > >
> > > Unfortunately I cannot tell from the bug report how many and which
> > > interfaces the emulated test device has. Hence it is unclear to me,
> > > when exactly probe() would fail cdc-acm.
> > >
> > > If you agree. I am attaching a putative fix.
> >
> > Let's see if it fixes the issue.
> >
> > #syz fix: https://github.com/google/kasan.git 6a3599ce
>
> Hi,
>
> did this ever produce a result? I saw none.

Hm, that's weird, maybe that's caused by putting the bot into CC. Let
me try that again.

#syz fix: https://github.com/google/kasan.git 6a3599ce

>
> Regards
> Oliver
>
> --
> You received this message because you are subscribed to the Google Groups "syzkaller-bugs" group.
> To unsubscribe from this group and stop receiving emails from it, send an email to [email protected].
> To view this discussion on the web visit https://groups.google.com/d/msgid/syzkaller-bugs/1565185131.15973.1.camel%40suse.com.

Attachments:

0001-usb-cdc-acm-make-sure-a-refcount-is-taken-early-enou.patch (1.71 kB)

2019-08-07 13:48:30

[permalink] [raw]

Subject: Re: KASAN: use-after-free Read in device_release_driver_internal

On Wed, Aug 7, 2019 at 3:44 PM Andrey Konovalov <[email protected]> wrote:
>
> On Wed, Aug 7, 2019 at 3:44 PM Andrey Konovalov <[email protected]> wrote:
> >
> > On Wed, Aug 7, 2019 at 3:38 PM Oliver Neukum <[email protected]> wrote:
> > >
> > > Am Dienstag, den 06.08.2019, 14:50 +0200 schrieb Andrey Konovalov:
> > > > On Tue, Aug 6, 2019 at 2:36 PM Oliver Neukum <[email protected]> wrote:
> > > > >
> > > > > Am Donnerstag, den 01.08.2019, 14:47 -0400 schrieb Alan Stern:
> > > > > >
> > > > > > I think this must be caused by an unbalanced refcount. That is,
> > > > > > something must drop one more reference to the device than it takes.
> > > > > > That would explain why the invalid access occurs inside a single
> > > > > > bus_remove_device() call, between the klist_del() and
> > > > > > device_release_driver().
> > > > > >
> > > > > > The kernel log indicates that the device was probed by rndis_wlan,
> > > > > > rndis_host, and cdc_acm, all of which got errors because of the
> > > > > > device's bogus descriptors. Probably one of them is messing up the
> > > > > > refcount.
> > > > >
> > > > > Hi,
> > > > >
> > > > > you made me look at cdc-acm. I suspect
> > > > >
> > > > > cae2bc768d176bfbdad7035bbcc3cdc973eb7984 ("usb: cdc-acm: Decrement tty port's refcount if probe() fail")
> > > > >
> > > > > is buggy decrementing the refcount on the interface in destroy()
> > > > > even before the refcount is increased.
> > > > >
> > > > > Unfortunately I cannot tell from the bug report how many and which
> > > > > interfaces the emulated test device has. Hence it is unclear to me,
> > > > > when exactly probe() would fail cdc-acm.
> > > > >
> > > > > If you agree. I am attaching a putative fix.
> > > >
> > > > Let's see if it fixes the issue.
> > > >
> > > > #syz fix: https://github.com/google/kasan.git 6a3599ce
> > >
> > > Hi,
> > >
> > > did this ever produce a result? I saw none.
> >
> > Hm, that's weird, maybe that's caused by putting the bot into CC. Let
> > me try that again.
> >
> > #syz fix: https://github.com/google/kasan.git 6a3599ce
>
> Oh, wait, it should be syz test =)
>
> #syz test: https://github.com/google/kasan.git 6a3599ce

And now I forgot the patch :(

#syz test: https://github.com/google/kasan.git 6a3599ce

>
> >
> > >
> > > Regards
> > > Oliver
> > >
> > > --
> > > You received this message because you are subscribed to the Google Groups "syzkaller-bugs" group.
> > > To unsubscribe from this group and stop receiving emails from it, send an email to [email protected].
> > > To view this discussion on the web visit https://groups.google.com/d/msgid/syzkaller-bugs/1565185131.15973.1.camel%40suse.com.

Attachments:

0001-usb-cdc-acm-make-sure-a-refcount-is-taken-early-enou.patch (1.71 kB)

2019-08-07 13:49:32

[permalink] [raw]

Subject: Re: KASAN: use-after-free Read in device_release_driver_internal

On Tue, Aug 6, 2019 at 5:34 PM Oliver Neukum <[email protected]> wrote:
>
> Am Dienstag, den 06.08.2019, 10:19 -0400 schrieb Alan Stern:
> > In any case, I don't know if this missing "get" would cause the
> > problem, but it might well.
>
> Hi,
>
> upon further thought, this should be automated. Checking for
> refcount leaks is KASAN's job. In particular, refcounts
> should not
>
> * decrease in probe()
> * increase in disconnect()
> * change in case probe() fails

It's probably a job for some other refcount debugging tool, but yes,
it would be nice to have a detector for this kind of stuff. It will
probably require some annotations in each place we want this kind of
checks to be performed.

>
> Regards
> Oliver
>

2019-08-07 14:00:21

by syzbot

[permalink] [raw]

Subject: Re: KASAN: use-after-free Read in device_release_driver_internal

Hello,

syzbot has tested the proposed patch but the reproducer still triggered
crash:
KASAN: use-after-free Read in device_release_driver_internal

usb 4-1: USB disconnect, device number 2
==================================================================
BUG: KASAN: use-after-free in __lock_acquire+0x3a5d/0x5340
kernel/locking/lockdep.c:3665
Read of size 8 at addr ffff8881d4a54510 by task kworker/0:3/2876

CPU: 0 PID: 2876 Comm: kworker/0:3 Not tainted 5.2.0-rc6+ #1
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS
Google 01/01/2011
Workqueue: usb_hub_wq hub_event
Call Trace:
__dump_stack lib/dump_stack.c:77 [inline]
dump_stack+0xca/0x13e lib/dump_stack.c:113
print_address_description+0x67/0x231 mm/kasan/report.c:188
__kasan_report.cold+0x1a/0x32 mm/kasan/report.c:317
kasan_report+0xe/0x20 mm/kasan/common.c:614
__lock_acquire+0x3a5d/0x5340 kernel/locking/lockdep.c:3665
lock_acquire+0x100/0x2b0 kernel/locking/lockdep.c:4303
__mutex_lock_common kernel/locking/mutex.c:926 [inline]
__mutex_lock+0xf9/0x12b0 kernel/locking/mutex.c:1073
device_release_driver_internal+0x23/0x4c0 drivers/base/dd.c:1109
bus_remove_device+0x2dc/0x4a0 drivers/base/bus.c:556
device_del+0x460/0xb80 drivers/base/core.c:2274
usb_disable_device+0x211/0x690 drivers/usb/core/message.c:1237
usb_disconnect+0x284/0x830 drivers/usb/core/hub.c:2199
hub_port_connect drivers/usb/core/hub.c:4949 [inline]
hub_port_connect_change drivers/usb/core/hub.c:5213 [inline]
port_event drivers/usb/core/hub.c:5359 [inline]
hub_event+0x13bd/0x3550 drivers/usb/core/hub.c:5441
process_one_work+0x905/0x1570 kernel/workqueue.c:2269
worker_thread+0x96/0xe20 kernel/workqueue.c:2415
kthread+0x30b/0x410 kernel/kthread.c:255
ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:352

Allocated by task 22:
save_stack+0x1b/0x80 mm/kasan/common.c:71
set_track mm/kasan/common.c:79 [inline]
__kasan_kmalloc mm/kasan/common.c:489 [inline]
__kasan_kmalloc.constprop.0+0xbf/0xd0 mm/kasan/common.c:462
kmalloc include/linux/slab.h:547 [inline]
kzalloc include/linux/slab.h:742 [inline]
usb_set_configuration+0x2c4/0x1670 drivers/usb/core/message.c:1846
generic_probe+0x9d/0xd5 drivers/usb/core/generic.c:210
usb_probe_device+0x99/0x100 drivers/usb/core/driver.c:266
really_probe+0x281/0x660 drivers/base/dd.c:509
driver_probe_device+0x104/0x210 drivers/base/dd.c:670
__device_attach_driver+0x1c2/0x220 drivers/base/dd.c:777
bus_for_each_drv+0x15c/0x1e0 drivers/base/bus.c:454
__device_attach+0x217/0x360 drivers/base/dd.c:843
bus_probe_device+0x1e4/0x290 drivers/base/bus.c:514
device_add+0xae6/0x16f0 drivers/base/core.c:2111
usb_new_device.cold+0x6a4/0xe61 drivers/usb/core/hub.c:2536
hub_port_connect drivers/usb/core/hub.c:5098 [inline]
hub_port_connect_change drivers/usb/core/hub.c:5213 [inline]
port_event drivers/usb/core/hub.c:5359 [inline]
hub_event+0x1abd/0x3550 drivers/usb/core/hub.c:5441
process_one_work+0x905/0x1570 kernel/workqueue.c:2269
worker_thread+0x96/0xe20 kernel/workqueue.c:2415
kthread+0x30b/0x410 kernel/kthread.c:255
ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:352

Freed by task 2876:
save_stack+0x1b/0x80 mm/kasan/common.c:71
set_track mm/kasan/common.c:79 [inline]
__kasan_slab_free+0x130/0x180 mm/kasan/common.c:451
slab_free_hook mm/slub.c:1421 [inline]
slab_free_freelist_hook mm/slub.c:1448 [inline]
slab_free mm/slub.c:2994 [inline]
kfree+0xd7/0x280 mm/slub.c:3949
device_release+0x71/0x200 drivers/base/core.c:1064
kobject_cleanup lib/kobject.c:691 [inline]
kobject_release lib/kobject.c:720 [inline]
kref_put include/linux/kref.h:65 [inline]
kobject_put+0x171/0x280 lib/kobject.c:737
put_device+0x1b/0x30 drivers/base/core.c:2210
klist_put+0xce/0x170 lib/klist.c:221
bus_remove_device+0x3a4/0x4a0 drivers/base/bus.c:552
device_del+0x460/0xb80 drivers/base/core.c:2274
usb_disable_device+0x211/0x690 drivers/usb/core/message.c:1237
usb_disconnect+0x284/0x830 drivers/usb/core/hub.c:2199
hub_port_connect drivers/usb/core/hub.c:4949 [inline]
hub_port_connect_change drivers/usb/core/hub.c:5213 [inline]
port_event drivers/usb/core/hub.c:5359 [inline]
hub_event+0x13bd/0x3550 drivers/usb/core/hub.c:5441
process_one_work+0x905/0x1570 kernel/workqueue.c:2269
worker_thread+0x96/0xe20 kernel/workqueue.c:2415
kthread+0x30b/0x410 kernel/kthread.c:255
ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:352

The buggy address belongs to the object at ffff8881d4a54400
which belongs to the cache kmalloc-2k of size 2048
The buggy address is located 272 bytes inside of
2048-byte region [ffff8881d4a54400, ffff8881d4a54c00)
The buggy address belongs to the page:
page:ffffea0007529400 refcount:1 mapcount:0 mapping:ffff8881dac02800
index:0x0 compound_mapcount: 0
flags: 0x200000000010200(slab|head)
raw: 0200000000010200 ffffea000753da00 0000000500000005 ffff8881dac02800
raw: 0000000000000000 00000000000f000f 00000001ffffffff 0000000000000000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
ffff8881d4a54400: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
ffff8881d4a54480: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
> ffff8881d4a54500: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
^
ffff8881d4a54580: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
ffff8881d4a54600: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
==================================================================

Tested on:

commit: 6a3599ce usb-fuzzer: main usb gadget fuzzer driver
git tree: https://github.com/google/kasan.git
console output: https://syzkaller.appspot.com/x/log.txt?x=132aca2c600000
kernel config: https://syzkaller.appspot.com/x/.config?x=700ca426ab83faae
compiler: gcc (GCC) 9.0.0 20181231 (experimental)

2019-08-07 14:13:53

by syzbot

[permalink] [raw]

Subject: Re: KASAN: use-after-free Read in device_release_driver_internal

Hello,

syzbot has tested the proposed patch and the reproducer did not trigger
crash:

Reported-and-tested-by:
[email protected]

Tested on:

commit: 6a3599ce usb-fuzzer: main usb gadget fuzzer driver
git tree: https://github.com/google/kasan.git
kernel config: https://syzkaller.appspot.com/x/.config?x=700ca426ab83faae
compiler: gcc (GCC) 9.0.0 20181231 (experimental)
patch: https://syzkaller.appspot.com/x/patch.diff?x=1245683c600000

Note: testing is done by a robot and is best-effort only.

2019-08-07 14:39:20

[permalink] [raw]

Subject: Re: KASAN: use-after-free Read in device_release_driver_internal

On Wed, Aug 7, 2019 at 3:44 PM Andrey Konovalov <[email protected]> wrote:
>
> On Wed, Aug 7, 2019 at 3:38 PM Oliver Neukum <[email protected]> wrote:
> >
> > Am Dienstag, den 06.08.2019, 14:50 +0200 schrieb Andrey Konovalov:
> > > On Tue, Aug 6, 2019 at 2:36 PM Oliver Neukum <[email protected]> wrote:
> > > >
> > > > Am Donnerstag, den 01.08.2019, 14:47 -0400 schrieb Alan Stern:
> > > > >
> > > > > I think this must be caused by an unbalanced refcount. That is,
> > > > > something must drop one more reference to the device than it takes.
> > > > > That would explain why the invalid access occurs inside a single
> > > > > bus_remove_device() call, between the klist_del() and
> > > > > device_release_driver().
> > > > >
> > > > > The kernel log indicates that the device was probed by rndis_wlan,
> > > > > rndis_host, and cdc_acm, all of which got errors because of the
> > > > > device's bogus descriptors. Probably one of them is messing up the
> > > > > refcount.
> > > >
> > > > Hi,
> > > >
> > > > you made me look at cdc-acm. I suspect
> > > >
> > > > cae2bc768d176bfbdad7035bbcc3cdc973eb7984 ("usb: cdc-acm: Decrement tty port's refcount if probe() fail")
> > > >
> > > > is buggy decrementing the refcount on the interface in destroy()
> > > > even before the refcount is increased.
> > > >
> > > > Unfortunately I cannot tell from the bug report how many and which
> > > > interfaces the emulated test device has. Hence it is unclear to me,
> > > > when exactly probe() would fail cdc-acm.
> > > >
> > > > If you agree. I am attaching a putative fix.
> > >
> > > Let's see if it fixes the issue.
> > >
> > > #syz fix: https://github.com/google/kasan.git 6a3599ce
> >
> > Hi,
> >
> > did this ever produce a result? I saw none.
>
> Hm, that's weird, maybe that's caused by putting the bot into CC. Let
> me try that again.
>
> #syz fix: https://github.com/google/kasan.git 6a3599ce

Oh, wait, it should be syz test =)

#syz test: https://github.com/google/kasan.git 6a3599ce

>
> >
> > Regards
> > Oliver
> >
> > --
> > You received this message because you are subscribed to the Google Groups "syzkaller-bugs" group.
> > To unsubscribe from this group and stop receiving emails from it, send an email to [email protected].
> > To view this discussion on the web visit https://groups.google.com/d/msgid/syzkaller-bugs/1565185131.15973.1.camel%40suse.com.

2019-08-07 17:53:22

by syzbot

[permalink] [raw]

Subject: Re: KASAN: use-after-free Read in device_release_driver_internal

Hello,

syzbot has tested the proposed patch but the reproducer still triggered
crash:
KASAN: use-after-free Read in device_release_driver_internal

==================================================================
BUG: KASAN: use-after-free in __lock_acquire+0x3a5d/0x5340
kernel/locking/lockdep.c:3665
Read of size 8 at addr ffff8881d4b1e710 by task kworker/1:2/89

CPU: 1 PID: 89 Comm: kworker/1:2 Not tainted 5.2.0-rc6+ #1
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS
Google 01/01/2011
Workqueue: usb_hub_wq hub_event
Call Trace:
__dump_stack lib/dump_stack.c:77 [inline]
dump_stack+0xca/0x13e lib/dump_stack.c:113
print_address_description+0x67/0x231 mm/kasan/report.c:188
__kasan_report.cold+0x1a/0x32 mm/kasan/report.c:317
kasan_report+0xe/0x20 mm/kasan/common.c:614
__lock_acquire+0x3a5d/0x5340 kernel/locking/lockdep.c:3665
lock_acquire+0x100/0x2b0 kernel/locking/lockdep.c:4303
__mutex_lock_common kernel/locking/mutex.c:926 [inline]
__mutex_lock+0xf9/0x12b0 kernel/locking/mutex.c:1073
device_release_driver_internal+0x23/0x4c0 drivers/base/dd.c:1109
bus_remove_device+0x2dc/0x4a0 drivers/base/bus.c:556
device_del+0x460/0xb80 drivers/base/core.c:2274
usb_disable_device+0x211/0x690 drivers/usb/core/message.c:1237
usb_disconnect+0x284/0x830 drivers/usb/core/hub.c:2199
hub_port_connect drivers/usb/core/hub.c:4949 [inline]
hub_port_connect_change drivers/usb/core/hub.c:5213 [inline]
port_event drivers/usb/core/hub.c:5359 [inline]
hub_event+0x13bd/0x3550 drivers/usb/core/hub.c:5441
process_one_work+0x905/0x1570 kernel/workqueue.c:2269
process_scheduled_works kernel/workqueue.c:2331 [inline]
worker_thread+0x7ab/0xe20 kernel/workqueue.c:2417
kthread+0x30b/0x410 kernel/kthread.c:255
ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:352

Allocated by task 89:
save_stack+0x1b/0x80 mm/kasan/common.c:71
set_track mm/kasan/common.c:79 [inline]
__kasan_kmalloc mm/kasan/common.c:489 [inline]
__kasan_kmalloc.constprop.0+0xbf/0xd0 mm/kasan/common.c:462
kmalloc include/linux/slab.h:547 [inline]
kzalloc include/linux/slab.h:742 [inline]
usb_set_configuration+0x2c4/0x1670 drivers/usb/core/message.c:1846
generic_probe+0x9d/0xd5 drivers/usb/core/generic.c:210
usb_probe_device+0x99/0x100 drivers/usb/core/driver.c:266
really_probe+0x281/0x660 drivers/base/dd.c:509
driver_probe_device+0x104/0x210 drivers/base/dd.c:670
__device_attach_driver+0x1c2/0x220 drivers/base/dd.c:777
bus_for_each_drv+0x15c/0x1e0 drivers/base/bus.c:454
__device_attach+0x217/0x360 drivers/base/dd.c:843
bus_probe_device+0x1e4/0x290 drivers/base/bus.c:514
device_add+0xae6/0x16f0 drivers/base/core.c:2111
usb_new_device.cold+0x6a4/0xe61 drivers/usb/core/hub.c:2536
hub_port_connect drivers/usb/core/hub.c:5098 [inline]
hub_port_connect_change drivers/usb/core/hub.c:5213 [inline]
port_event drivers/usb/core/hub.c:5359 [inline]
hub_event+0x1abd/0x3550 drivers/usb/core/hub.c:5441
process_one_work+0x905/0x1570 kernel/workqueue.c:2269
worker_thread+0x96/0xe20 kernel/workqueue.c:2415
kthread+0x30b/0x410 kernel/kthread.c:255
ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:352

Freed by task 89:
save_stack+0x1b/0x80 mm/kasan/common.c:71
set_track mm/kasan/common.c:79 [inline]
__kasan_slab_free+0x130/0x180 mm/kasan/common.c:451
slab_free_hook mm/slub.c:1421 [inline]
slab_free_freelist_hook mm/slub.c:1448 [inline]
slab_free mm/slub.c:2994 [inline]
kfree+0xd7/0x280 mm/slub.c:3949
device_release+0x71/0x200 drivers/base/core.c:1064
kobject_cleanup lib/kobject.c:691 [inline]
kobject_release lib/kobject.c:720 [inline]
kref_put include/linux/kref.h:65 [inline]
kobject_put+0x171/0x280 lib/kobject.c:737
put_device+0x1b/0x30 drivers/base/core.c:2210
klist_put+0xce/0x170 lib/klist.c:221
bus_remove_device+0x3a4/0x4a0 drivers/base/bus.c:552
device_del+0x460/0xb80 drivers/base/core.c:2274
usb_disable_device+0x211/0x690 drivers/usb/core/message.c:1237
usb_disconnect+0x284/0x830 drivers/usb/core/hub.c:2199
hub_port_connect drivers/usb/core/hub.c:4949 [inline]
hub_port_connect_change drivers/usb/core/hub.c:5213 [inline]
port_event drivers/usb/core/hub.c:5359 [inline]
hub_event+0x13bd/0x3550 drivers/usb/core/hub.c:5441
process_one_work+0x905/0x1570 kernel/workqueue.c:2269
process_scheduled_works kernel/workqueue.c:2331 [inline]
worker_thread+0x7ab/0xe20 kernel/workqueue.c:2417
kthread+0x30b/0x410 kernel/kthread.c:255
ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:352

The buggy address belongs to the object at ffff8881d4b1e600
which belongs to the cache kmalloc-2k of size 2048
The buggy address is located 272 bytes inside of
2048-byte region [ffff8881d4b1e600, ffff8881d4b1ee00)
The buggy address belongs to the page:
page:ffffea000752c600 refcount:1 mapcount:0 mapping:ffff8881dac02800
index:0x0 compound_mapcount: 0
flags: 0x200000000010200(slab|head)
raw: 0200000000010200 ffffea0007536e00 0000000600000006 ffff8881dac02800
raw: 0000000000000000 00000000800f000f 00000001ffffffff 0000000000000000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
ffff8881d4b1e600: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
ffff8881d4b1e680: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
> ffff8881d4b1e700: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
^
ffff8881d4b1e780: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
ffff8881d4b1e800: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
==================================================================

Tested on:

commit: 6a3599ce usb-fuzzer: main usb gadget fuzzer driver
git tree: https://github.com/google/kasan.git
console output: https://syzkaller.appspot.com/x/log.txt?x=142eec8c600000
kernel config: https://syzkaller.appspot.com/x/.config?x=700ca426ab83faae
compiler: gcc (GCC) 9.0.0 20181231 (experimental)
patch: https://syzkaller.appspot.com/x/patch.diff?x=15d95bf6600000

2019-08-07 18:07:16

[permalink] [raw]

Subject: Re: KASAN: use-after-free Read in device_release_driver_internal

On Wed, 7 Aug 2019, syzbot wrote:

> Hello,
>
> syzbot has tested the proposed patch but the reproducer still triggered
> crash:
> KASAN: use-after-free Read in device_release_driver_internal

> Tested on:
>
> commit: 6a3599ce usb-fuzzer: main usb gadget fuzzer driver
> git tree: https://github.com/google/kasan.git
> console output: https://syzkaller.appspot.com/x/log.txt?x=142eec8c600000
> kernel config: https://syzkaller.appspot.com/x/.config?x=700ca426ab83faae
> compiler: gcc (GCC) 9.0.0 20181231 (experimental)
> patch: https://syzkaller.appspot.com/x/patch.diff?x=15d95bf6600000

The kernel log is pretty definite here:

[ 40.270346][ T89] cdc_acm 5-1:0.234: Refcount before probe: 3
[ 40.284514][ T89] cdc_acm 5-1:0.234: invalid descriptor buffer length
[ 40.284523][ T89] cdc_acm 5-1:0.234: No union descriptor, testing for castrated device
[ 40.285322][ T89] cdc_acm 5-1:0.234: Refcount after probe: 2

2 < 3. So let's combine the diagnostic patch with Oliver's proposed
solution.

Alan Stern

#syz test: https://github.com/google/kasan.git 6a3599ce

Index: usb-devel/drivers/usb/core/driver.c
===================================================================
--- usb-devel.orig/drivers/usb/core/driver.c
+++ usb-devel/drivers/usb/core/driver.c
@@ -358,7 +358,11 @@ static int usb_probe_interface(struct de
intf->needs_altsetting0 = 0;
}

+ dev_info(&intf->dev, "Refcount before probe: %d\n",
+ refcount_read(&intf->dev.kobj.kref.refcount));
error = driver->probe(intf, id);
+ dev_info(&intf->dev, "Refcount after probe: %d\n",
+ refcount_read(&intf->dev.kobj.kref.refcount));
if (error)
goto err;

Index: usb-devel/drivers/usb/class/cdc-acm.c
===================================================================
--- usb-devel.orig/drivers/usb/class/cdc-acm.c
+++ usb-devel/drivers/usb/class/cdc-acm.c
@@ -1301,10 +1301,6 @@ made_compressed_probe:
tty_port_init(&acm->port);
acm->port.ops = &acm_port_ops;

- minor = acm_alloc_minor(acm);
- if (minor < 0)
- goto alloc_fail1;
-
ctrlsize = usb_endpoint_maxp(epctrl);
readsize = usb_endpoint_maxp(epread) *
(quirks == SINGLE_RX_URB ? 1 : 2);
@@ -1312,6 +1308,13 @@ made_compressed_probe:
acm->writesize = usb_endpoint_maxp(epwrite) * 20;
acm->control = control_interface;
acm->data = data_interface;
+
+ usb_get_intf(acm->control); /* undone in destroy() */
+
+ minor = acm_alloc_minor(acm);
+ if (minor < 0)
+ goto alloc_fail1;
+
acm->minor = minor;
acm->dev = usb_dev;
if (h.usb_cdc_acm_descriptor)
@@ -1458,7 +1461,6 @@ skip_countries:
usb_driver_claim_interface(&acm_driver, data_interface, acm);
usb_set_intfdata(data_interface, acm);

- usb_get_intf(control_interface);
tty_dev = tty_port_register_device(&acm->port, acm_tty_driver, minor,
&control_interface->dev);
if (IS_ERR(tty_dev)) {

2019-08-07 18:24:09

by syzbot

[permalink] [raw]

Subject: Re: KASAN: use-after-free Read in device_release_driver_internal

Hello,

syzbot has tested the proposed patch and the reproducer did not trigger
crash:

Reported-and-tested-by:
[email protected]

Tested on:

commit: 6a3599ce usb-fuzzer: main usb gadget fuzzer driver
git tree: https://github.com/google/kasan.git
kernel config: https://syzkaller.appspot.com/x/.config?x=700ca426ab83faae
compiler: gcc (GCC) 9.0.0 20181231 (experimental)
patch: https://syzkaller.appspot.com/x/patch.diff?x=132eec8c600000

Note: testing is done by a robot and is best-effort only.

2019-08-07 18:32:52

[permalink] [raw]

Subject: Re: KASAN: use-after-free Read in device_release_driver_internal

On Wed, 7 Aug 2019, syzbot wrote:

> Hello,
>
> syzbot has tested the proposed patch and the reproducer did not trigger
> crash:
>
> Reported-and-tested-by:
> [email protected]
>
> Tested on:
>
> commit: 6a3599ce usb-fuzzer: main usb gadget fuzzer driver
> git tree: https://github.com/google/kasan.git
> kernel config: https://syzkaller.appspot.com/x/.config?x=700ca426ab83faae
> compiler: gcc (GCC) 9.0.0 20181231 (experimental)
> patch: https://syzkaller.appspot.com/x/patch.diff?x=132eec8c600000
>
> Note: testing is done by a robot and is best-effort only.

Andrey, is there any way to get the console output from this test?

Alan Stern

2019-08-07 19:19:09

[permalink] [raw]

Subject: Re: KASAN: use-after-free Read in device_release_driver_internal

On Wed, 7 Aug 2019, syzbot wrote:

> Hello,
>
> syzbot has tested the proposed patch but the reproducer still triggered
> crash:
> KASAN: use-after-free Read in device_release_driver_internal
>
> usb 4-1: USB disconnect, device number 2
> ==================================================================
> BUG: KASAN: use-after-free in __lock_acquire+0x3a5d/0x5340
> kernel/locking/lockdep.c:3665
> Read of size 8 at addr ffff8881d4a54510 by task kworker/0:3/2876
>
> CPU: 0 PID: 2876 Comm: kworker/0:3 Not tainted 5.2.0-rc6+ #1
> Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS
> Google 01/01/2011
> Workqueue: usb_hub_wq hub_event
> Call Trace:
> __dump_stack lib/dump_stack.c:77 [inline]
> dump_stack+0xca/0x13e lib/dump_stack.c:113
> print_address_description+0x67/0x231 mm/kasan/report.c:188
> __kasan_report.cold+0x1a/0x32 mm/kasan/report.c:317
> kasan_report+0xe/0x20 mm/kasan/common.c:614
> __lock_acquire+0x3a5d/0x5340 kernel/locking/lockdep.c:3665
> lock_acquire+0x100/0x2b0 kernel/locking/lockdep.c:4303
> __mutex_lock_common kernel/locking/mutex.c:926 [inline]
> __mutex_lock+0xf9/0x12b0 kernel/locking/mutex.c:1073
> device_release_driver_internal+0x23/0x4c0 drivers/base/dd.c:1109
> bus_remove_device+0x2dc/0x4a0 drivers/base/bus.c:556
> device_del+0x460/0xb80 drivers/base/core.c:2274
> usb_disable_device+0x211/0x690 drivers/usb/core/message.c:1237
> usb_disconnect+0x284/0x830 drivers/usb/core/hub.c:2199
> hub_port_connect drivers/usb/core/hub.c:4949 [inline]
> hub_port_connect_change drivers/usb/core/hub.c:5213 [inline]
> port_event drivers/usb/core/hub.c:5359 [inline]
> hub_event+0x13bd/0x3550 drivers/usb/core/hub.c:5441
> process_one_work+0x905/0x1570 kernel/workqueue.c:2269
> worker_thread+0x96/0xe20 kernel/workqueue.c:2415
> kthread+0x30b/0x410 kernel/kthread.c:255
> ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:352
>
> Allocated by task 22:
> save_stack+0x1b/0x80 mm/kasan/common.c:71
> set_track mm/kasan/common.c:79 [inline]
> __kasan_kmalloc mm/kasan/common.c:489 [inline]
> __kasan_kmalloc.constprop.0+0xbf/0xd0 mm/kasan/common.c:462
> kmalloc include/linux/slab.h:547 [inline]
> kzalloc include/linux/slab.h:742 [inline]
> usb_set_configuration+0x2c4/0x1670 drivers/usb/core/message.c:1846
> generic_probe+0x9d/0xd5 drivers/usb/core/generic.c:210
> usb_probe_device+0x99/0x100 drivers/usb/core/driver.c:266
> really_probe+0x281/0x660 drivers/base/dd.c:509
> driver_probe_device+0x104/0x210 drivers/base/dd.c:670
> __device_attach_driver+0x1c2/0x220 drivers/base/dd.c:777
> bus_for_each_drv+0x15c/0x1e0 drivers/base/bus.c:454
> __device_attach+0x217/0x360 drivers/base/dd.c:843
> bus_probe_device+0x1e4/0x290 drivers/base/bus.c:514
> device_add+0xae6/0x16f0 drivers/base/core.c:2111
> usb_new_device.cold+0x6a4/0xe61 drivers/usb/core/hub.c:2536
> hub_port_connect drivers/usb/core/hub.c:5098 [inline]
> hub_port_connect_change drivers/usb/core/hub.c:5213 [inline]
> port_event drivers/usb/core/hub.c:5359 [inline]
> hub_event+0x1abd/0x3550 drivers/usb/core/hub.c:5441
> process_one_work+0x905/0x1570 kernel/workqueue.c:2269
> worker_thread+0x96/0xe20 kernel/workqueue.c:2415
> kthread+0x30b/0x410 kernel/kthread.c:255
> ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:352
>
> Freed by task 2876:
> save_stack+0x1b/0x80 mm/kasan/common.c:71
> set_track mm/kasan/common.c:79 [inline]
> __kasan_slab_free+0x130/0x180 mm/kasan/common.c:451
> slab_free_hook mm/slub.c:1421 [inline]
> slab_free_freelist_hook mm/slub.c:1448 [inline]
> slab_free mm/slub.c:2994 [inline]
> kfree+0xd7/0x280 mm/slub.c:3949
> device_release+0x71/0x200 drivers/base/core.c:1064
> kobject_cleanup lib/kobject.c:691 [inline]
> kobject_release lib/kobject.c:720 [inline]
> kref_put include/linux/kref.h:65 [inline]
> kobject_put+0x171/0x280 lib/kobject.c:737
> put_device+0x1b/0x30 drivers/base/core.c:2210
> klist_put+0xce/0x170 lib/klist.c:221
> bus_remove_device+0x3a4/0x4a0 drivers/base/bus.c:552
> device_del+0x460/0xb80 drivers/base/core.c:2274
> usb_disable_device+0x211/0x690 drivers/usb/core/message.c:1237
> usb_disconnect+0x284/0x830 drivers/usb/core/hub.c:2199
> hub_port_connect drivers/usb/core/hub.c:4949 [inline]
> hub_port_connect_change drivers/usb/core/hub.c:5213 [inline]
> port_event drivers/usb/core/hub.c:5359 [inline]
> hub_event+0x13bd/0x3550 drivers/usb/core/hub.c:5441
> process_one_work+0x905/0x1570 kernel/workqueue.c:2269
> worker_thread+0x96/0xe20 kernel/workqueue.c:2415
> kthread+0x30b/0x410 kernel/kthread.c:255
> ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:352
>
> The buggy address belongs to the object at ffff8881d4a54400
> which belongs to the cache kmalloc-2k of size 2048
> The buggy address is located 272 bytes inside of
> 2048-byte region [ffff8881d4a54400, ffff8881d4a54c00)
> The buggy address belongs to the page:
> page:ffffea0007529400 refcount:1 mapcount:0 mapping:ffff8881dac02800
> index:0x0 compound_mapcount: 0
> flags: 0x200000000010200(slab|head)
> raw: 0200000000010200 ffffea000753da00 0000000500000005 ffff8881dac02800
> raw: 0000000000000000 00000000000f000f 00000001ffffffff 0000000000000000
> page dumped because: kasan: bad access detected
>
> Memory state around the buggy address:
> ffff8881d4a54400: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
> ffff8881d4a54480: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
> > ffff8881d4a54500: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
> ^
> ffff8881d4a54580: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
> ffff8881d4a54600: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
> ==================================================================
>
>
> Tested on:
>
> commit: 6a3599ce usb-fuzzer: main usb gadget fuzzer driver
> git tree: https://github.com/google/kasan.git
> console output: https://syzkaller.appspot.com/x/log.txt?x=132aca2c600000
> kernel config: https://syzkaller.appspot.com/x/.config?x=700ca426ab83faae
> compiler: gcc (GCC) 9.0.0 20181231 (experimental)

Maybe this will help pinpoint where the problem occurs. The kernel log
should indicate the before and after refcount values for the interface.

Alan Stern

#syz test: https://github.com/google/kasan.git 6a3599ce

Index: usb-devel/drivers/usb/core/driver.c
===================================================================
--- usb-devel.orig/drivers/usb/core/driver.c
+++ usb-devel/drivers/usb/core/driver.c
@@ -358,7 +358,11 @@ static int usb_probe_interface(struct de
intf->needs_altsetting0 = 0;
}

+ dev_info(&intf->dev, "Refcount before probe: %d\n",
+ refcount_read(&intf->dev.kobj.kref.refcount));
error = driver->probe(intf, id);
+ dev_info(&intf->dev, "Refcount after probe: %d\n",
+ refcount_read(&intf->dev.kobj.kref.refcount));
if (error)
goto err;

2019-08-08 12:37:58

[permalink] [raw]

Subject: Re: KASAN: use-after-free Read in device_release_driver_internal

On Wed, Aug 7, 2019 at 8:31 PM Alan Stern <[email protected]> wrote:
>
> On Wed, 7 Aug 2019, syzbot wrote:
>
> > Hello,
> >
> > syzbot has tested the proposed patch and the reproducer did not trigger
> > crash:
> >
> > Reported-and-tested-by:
> > [email protected]
> >
> > Tested on:
> >
> > commit: 6a3599ce usb-fuzzer: main usb gadget fuzzer driver
> > git tree: https://github.com/google/kasan.git
> > kernel config: https://syzkaller.appspot.com/x/.config?x=700ca426ab83faae
> > compiler: gcc (GCC) 9.0.0 20181231 (experimental)
> > patch: https://syzkaller.appspot.com/x/patch.diff?x=132eec8c600000
> >
> > Note: testing is done by a robot and is best-effort only.
>
> Andrey, is there any way to get the console output from this test?

Dmitry, would it be possible to link console log for successful tests as well?

>
> Alan Stern
>

2019-08-08 12:45:45

by Dmitry Vyukov

[permalink] [raw]

Subject: Re: KASAN: use-after-free Read in device_release_driver_internal

On Thu, Aug 8, 2019 at 2:28 PM Andrey Konovalov <[email protected]> wrote:
>
> On Wed, Aug 7, 2019 at 8:31 PM Alan Stern <[email protected]> wrote:
> >
> > On Wed, 7 Aug 2019, syzbot wrote:
> >
> > > Hello,
> > >
> > > syzbot has tested the proposed patch and the reproducer did not trigger
> > > crash:
> > >
> > > Reported-and-tested-by:
> > > [email protected]
> > >
> > > Tested on:
> > >
> > > commit: 6a3599ce usb-fuzzer: main usb gadget fuzzer driver
> > > git tree: https://github.com/google/kasan.git
> > > kernel config: https://syzkaller.appspot.com/x/.config?x=700ca426ab83faae
> > > compiler: gcc (GCC) 9.0.0 20181231 (experimental)
> > > patch: https://syzkaller.appspot.com/x/patch.diff?x=132eec8c600000
> > >
> > > Note: testing is done by a robot and is best-effort only.
> >
> > Andrey, is there any way to get the console output from this test?
>
> Dmitry, would it be possible to link console log for successful tests as well?

Yes. Start by filing a feature request at
https://github.com/google/syzkaller/issues

2019-08-08 14:01:01

[permalink] [raw]

Subject: Re: KASAN: use-after-free Read in device_release_driver_internal

On Thu, 8 Aug 2019, Andrey Konovalov wrote:

> On Thu, Aug 8, 2019 at 2:44 PM Dmitry Vyukov <[email protected]> wrote:
> >
> > On Thu, Aug 8, 2019 at 2:28 PM Andrey Konovalov <[email protected]> wrote:
> > >
> > > On Wed, Aug 7, 2019 at 8:31 PM Alan Stern <[email protected]> wrote:
> > > >
> > > > On Wed, 7 Aug 2019, syzbot wrote:
> > > >
> > > > > Hello,
> > > > >
> > > > > syzbot has tested the proposed patch and the reproducer did not trigger
> > > > > crash:
> > > > >
> > > > > Reported-and-tested-by:
> > > > > [email protected]
> > > > >
> > > > > Tested on:
> > > > >
> > > > > commit: 6a3599ce usb-fuzzer: main usb gadget fuzzer driver
> > > > > git tree: https://github.com/google/kasan.git
> > > > > kernel config: https://syzkaller.appspot.com/x/.config?x=700ca426ab83faae
> > > > > compiler: gcc (GCC) 9.0.0 20181231 (experimental)
> > > > > patch: https://syzkaller.appspot.com/x/patch.diff?x=132eec8c600000
> > > > >
> > > > > Note: testing is done by a robot and is best-effort only.
> > > >
> > > > Andrey, is there any way to get the console output from this test?
> > >
> > > Dmitry, would it be possible to link console log for successful tests as well?
> >
> > Yes. Start by filing a feature request at
> > https://github.com/google/syzkaller/issues
>
> Filed https://github.com/google/syzkaller/issues/1322
>
> Alan, for now I've applied your patch and run the reproducer manually:
>
> [ 90.844643][ T74] usb 1-1: new high-speed USB device number 2
> using dummy_hcd
> [ 91.085789][ T74] usb 1-1: Using ep0 maxpacket: 16
> [ 91.204698][ T74] usb 1-1: config 0 has an invalid interface
> number: 234 but max is 0
> [ 91.209137][ T74] usb 1-1: config 0 has no interface number 0
> [ 91.211599][ T74] usb 1-1: config 0 interface 234 altsetting 0
> endpoint 0x8D has an inva1
> [ 91.216162][ T74] usb 1-1: config 0 interface 234 altsetting 0
> endpoint 0x7 has invalid 4
> [ 91.218211][ T74] usb 1-1: config 0 interface 234 altsetting 0
> bulk endpoint 0x7 has inv4
> [ 91.220131][ T74] usb 1-1: config 0 interface 234 altsetting 0
> bulk endpoint 0x8F has in0
> [ 91.222052][ T74] usb 1-1: New USB device found, idVendor=0421,
> idProduct=0486, bcdDevic7
> [ 91.223851][ T74] usb 1-1: New USB device strings: Mfr=0,
> Product=0, SerialNumber=0
> [ 91.233180][ T74] usb 1-1: config 0 descriptor??
> [ 91.270222][ T74] rndis_wlan 1-1:0.234: Refcount before probe: 3
> [ 91.275464][ T74] rndis_wlan 1-1:0.234: invalid descriptor buffer length
> [ 91.277558][ T74] usb 1-1: bad CDC descriptors
> [ 91.279716][ T74] rndis_wlan 1-1:0.234: Refcount after probe: 3
> [ 91.281378][ T74] rndis_host 1-1:0.234: Refcount before probe: 3
> [ 91.283303][ T74] rndis_host 1-1:0.234: invalid descriptor buffer length
> [ 91.284724][ T74] usb 1-1: bad CDC descriptors
> [ 91.286004][ T74] rndis_host 1-1:0.234: Refcount after probe: 3
> [ 91.287318][ T74] cdc_acm 1-1:0.234: Refcount before probe: 3
> [ 91.288513][ T74] cdc_acm 1-1:0.234: invalid descriptor buffer length
> [ 91.289835][ T74] cdc_acm 1-1:0.234: No union descriptor, testing
> for castrated device
> [ 91.291555][ T74] cdc_acm 1-1:0.234: Refcount after probe: 3
> [ 91.292766][ T74] cdc_acm: probe of 1-1:0.234 failed with error -12
> [ 92.001549][ T96] usb 1-1: USB disconnect, device number 2

Ah, that looks right, thank you. The patch worked correctly -- good
work Oliver!

Alan Stern

2019-08-08 14:22:43

[permalink] [raw]

Subject: Re: KASAN: use-after-free Read in device_release_driver_internal

On Thu, Aug 8, 2019 at 2:44 PM Dmitry Vyukov <[email protected]> wrote:
>
> On Thu, Aug 8, 2019 at 2:28 PM Andrey Konovalov <[email protected]> wrote:
> >
> > On Wed, Aug 7, 2019 at 8:31 PM Alan Stern <[email protected]> wrote:
> > >
> > > On Wed, 7 Aug 2019, syzbot wrote:
> > >
> > > > Hello,
> > > >
> > > > syzbot has tested the proposed patch and the reproducer did not trigger
> > > > crash:
> > > >
> > > > Reported-and-tested-by:
> > > > [email protected]
> > > >
> > > > Tested on:
> > > >
> > > > commit: 6a3599ce usb-fuzzer: main usb gadget fuzzer driver
> > > > git tree: https://github.com/google/kasan.git
> > > > kernel config: https://syzkaller.appspot.com/x/.config?x=700ca426ab83faae
> > > > compiler: gcc (GCC) 9.0.0 20181231 (experimental)
> > > > patch: https://syzkaller.appspot.com/x/patch.diff?x=132eec8c600000
> > > >
> > > > Note: testing is done by a robot and is best-effort only.
> > >
> > > Andrey, is there any way to get the console output from this test?
> >
> > Dmitry, would it be possible to link console log for successful tests as well?
>
> Yes. Start by filing a feature request at
> https://github.com/google/syzkaller/issues

Filed https://github.com/google/syzkaller/issues/1322

Alan, for now I've applied your patch and run the reproducer manually:

[ 90.844643][ T74] usb 1-1: new high-speed USB device number 2
using dummy_hcd
[ 91.085789][ T74] usb 1-1: Using ep0 maxpacket: 16
[ 91.204698][ T74] usb 1-1: config 0 has an invalid interface
number: 234 but max is 0
[ 91.209137][ T74] usb 1-1: config 0 has no interface number 0
[ 91.211599][ T74] usb 1-1: config 0 interface 234 altsetting 0
endpoint 0x8D has an inva1
[ 91.216162][ T74] usb 1-1: config 0 interface 234 altsetting 0
endpoint 0x7 has invalid 4
[ 91.218211][ T74] usb 1-1: config 0 interface 234 altsetting 0
bulk endpoint 0x7 has inv4
[ 91.220131][ T74] usb 1-1: config 0 interface 234 altsetting 0
bulk endpoint 0x8F has in0
[ 91.222052][ T74] usb 1-1: New USB device found, idVendor=0421,
idProduct=0486, bcdDevic7
[ 91.223851][ T74] usb 1-1: New USB device strings: Mfr=0,
Product=0, SerialNumber=0
[ 91.233180][ T74] usb 1-1: config 0 descriptor??
[ 91.270222][ T74] rndis_wlan 1-1:0.234: Refcount before probe: 3
[ 91.275464][ T74] rndis_wlan 1-1:0.234: invalid descriptor buffer length
[ 91.277558][ T74] usb 1-1: bad CDC descriptors
[ 91.279716][ T74] rndis_wlan 1-1:0.234: Refcount after probe: 3
[ 91.281378][ T74] rndis_host 1-1:0.234: Refcount before probe: 3
[ 91.283303][ T74] rndis_host 1-1:0.234: invalid descriptor buffer length
[ 91.284724][ T74] usb 1-1: bad CDC descriptors
[ 91.286004][ T74] rndis_host 1-1:0.234: Refcount after probe: 3
[ 91.287318][ T74] cdc_acm 1-1:0.234: Refcount before probe: 3
[ 91.288513][ T74] cdc_acm 1-1:0.234: invalid descriptor buffer length
[ 91.289835][ T74] cdc_acm 1-1:0.234: No union descriptor, testing
for castrated device
[ 91.291555][ T74] cdc_acm 1-1:0.234: Refcount after probe: 3
[ 91.292766][ T74] cdc_acm: probe of 1-1:0.234 failed with error -12
[ 92.001549][ T96] usb 1-1: USB disconnect, device number 2

2019-08-13 13:24:26

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Subject: Re: KASAN: use-after-free Read in device_release_driver_internal

Am Dienstag, den 13.08.2019, 14:42 +0200 schrieb Andrey Konovalov:
> >

[..]

> On Thu, Aug 8, 2019 at 4:00 PM Alan Stern <[email protected]> wrote:
> > Ah, that looks right, thank you. The patch worked correctly -- good
> > work Oliver!
>
> Great! Just a reminder to submit the fix :)

I did last week:
https://patchwork.kernel.org/patch/11084261/

Regards
Oliver

2019-08-13 15:19:10

by Greg KH

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Subject: Re: KASAN: use-after-free Read in device_release_driver_internal

On Tue, Aug 13, 2019 at 03:22:15PM +0200, Oliver Neukum wrote:
> Am Dienstag, den 13.08.2019, 14:42 +0200 schrieb Andrey Konovalov:
> > >
>
>
> [..]
>
> > On Thu, Aug 8, 2019 at 4:00 PM Alan Stern <[email protected]> wrote:
> > > Ah, that looks right, thank you. The patch worked correctly -- good
> > > work Oliver!
> >
> > Great! Just a reminder to submit the fix :)
>
> I did last week:
> https://patchwork.kernel.org/patch/11084261/

Give me a chance to catch up :)

2019-08-13 15:28:03

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Subject: Re: KASAN: use-after-free Read in device_release_driver_internal

On Thu, Aug 8, 2019 at 4:00 PM Alan Stern <[email protected]> wrote:
>
> On Thu, 8 Aug 2019, Andrey Konovalov wrote:
>
> > On Thu, Aug 8, 2019 at 2:44 PM Dmitry Vyukov <[email protected]> wrote:
> > >
> > > On Thu, Aug 8, 2019 at 2:28 PM Andrey Konovalov <[email protected]> wrote:
> > > >
> > > > On Wed, Aug 7, 2019 at 8:31 PM Alan Stern <[email protected]> wrote:
> > > > >
> > > > > On Wed, 7 Aug 2019, syzbot wrote:
> > > > >
> > > > > > Hello,
> > > > > >
> > > > > > syzbot has tested the proposed patch and the reproducer did not trigger
> > > > > > crash:
> > > > > >
> > > > > > Reported-and-tested-by:
> > > > > > [email protected]
> > > > > >
> > > > > > Tested on:
> > > > > >
> > > > > > commit: 6a3599ce usb-fuzzer: main usb gadget fuzzer driver
> > > > > > git tree: https://github.com/google/kasan.git
> > > > > > kernel config: https://syzkaller.appspot.com/x/.config?x=700ca426ab83faae
> > > > > > compiler: gcc (GCC) 9.0.0 20181231 (experimental)
> > > > > > patch: https://syzkaller.appspot.com/x/patch.diff?x=132eec8c600000
> > > > > >
> > > > > > Note: testing is done by a robot and is best-effort only.
> > > > >
> > > > > Andrey, is there any way to get the console output from this test?
> > > >
> > > > Dmitry, would it be possible to link console log for successful tests as well?
> > >
> > > Yes. Start by filing a feature request at
> > > https://github.com/google/syzkaller/issues
> >
> > Filed https://github.com/google/syzkaller/issues/1322
> >
> > Alan, for now I've applied your patch and run the reproducer manually:
> >
> > [ 90.844643][ T74] usb 1-1: new high-speed USB device number 2
> > using dummy_hcd
> > [ 91.085789][ T74] usb 1-1: Using ep0 maxpacket: 16
> > [ 91.204698][ T74] usb 1-1: config 0 has an invalid interface
> > number: 234 but max is 0
> > [ 91.209137][ T74] usb 1-1: config 0 has no interface number 0
> > [ 91.211599][ T74] usb 1-1: config 0 interface 234 altsetting 0
> > endpoint 0x8D has an inva1
> > [ 91.216162][ T74] usb 1-1: config 0 interface 234 altsetting 0
> > endpoint 0x7 has invalid 4
> > [ 91.218211][ T74] usb 1-1: config 0 interface 234 altsetting 0
> > bulk endpoint 0x7 has inv4
> > [ 91.220131][ T74] usb 1-1: config 0 interface 234 altsetting 0
> > bulk endpoint 0x8F has in0
> > [ 91.222052][ T74] usb 1-1: New USB device found, idVendor=0421,
> > idProduct=0486, bcdDevic7
> > [ 91.223851][ T74] usb 1-1: New USB device strings: Mfr=0,
> > Product=0, SerialNumber=0
> > [ 91.233180][ T74] usb 1-1: config 0 descriptor??
> > [ 91.270222][ T74] rndis_wlan 1-1:0.234: Refcount before probe: 3
> > [ 91.275464][ T74] rndis_wlan 1-1:0.234: invalid descriptor buffer length
> > [ 91.277558][ T74] usb 1-1: bad CDC descriptors
> > [ 91.279716][ T74] rndis_wlan 1-1:0.234: Refcount after probe: 3
> > [ 91.281378][ T74] rndis_host 1-1:0.234: Refcount before probe: 3
> > [ 91.283303][ T74] rndis_host 1-1:0.234: invalid descriptor buffer length
> > [ 91.284724][ T74] usb 1-1: bad CDC descriptors
> > [ 91.286004][ T74] rndis_host 1-1:0.234: Refcount after probe: 3
> > [ 91.287318][ T74] cdc_acm 1-1:0.234: Refcount before probe: 3
> > [ 91.288513][ T74] cdc_acm 1-1:0.234: invalid descriptor buffer length
> > [ 91.289835][ T74] cdc_acm 1-1:0.234: No union descriptor, testing
> > for castrated device
> > [ 91.291555][ T74] cdc_acm 1-1:0.234: Refcount after probe: 3
> > [ 91.292766][ T74] cdc_acm: probe of 1-1:0.234 failed with error -12
> > [ 92.001549][ T96] usb 1-1: USB disconnect, device number 2
>
> Ah, that looks right, thank you. The patch worked correctly -- good
> work Oliver!

Great! Just a reminder to submit the fix :)

2019-08-13 16:03:44

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Subject: Re: KASAN: use-after-free Read in device_release_driver_internal

On Tue, Aug 13, 2019 at 3:22 PM Oliver Neukum <[email protected]> wrote:
>
> Am Dienstag, den 13.08.2019, 14:42 +0200 schrieb Andrey Konovalov:
> > >
>
>
> [..]
>
> > On Thu, Aug 8, 2019 at 4:00 PM Alan Stern <[email protected]> wrote:
> > > Ah, that looks right, thank you. The patch worked correctly -- good
> > > work Oliver!
> >
> > Great! Just a reminder to submit the fix :)
>
> I did last week:
> https://patchwork.kernel.org/patch/11084261/

Ah, perfect, thank you! Apparently I've missed it.

2019-08-13 16:05:11