Hello,
syzbot found the following issue on:
HEAD commit: 7b4ea945 Revert "x86/mm/64: Do not sync vmalloc/ioremap ma..
git tree: https://git.kernel.org/pub/scm/linux/kernel/git/gregkh/usb.git usb-testing
console output: https://syzkaller.appspot.com/x/log.txt?x=108adf32900000
kernel config: https://syzkaller.appspot.com/x/.config?x=72a84c46d0c668c
dashboard link: https://syzkaller.appspot.com/bug?extid=9e04e2df4a32fb661daf
compiler: gcc (GCC) 10.1.0-syz 20200507
Unfortunately, I don't have any reproducer for this issue yet.
IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: [email protected]
==================================================================
BUG: KASAN: use-after-free in usb_submit_urb+0x10c4/0x13e0 drivers/usb/core/urb.c:368
Read of size 4 at addr ffff8881caa52018 by task syz-executor.3/13922
CPU: 1 PID: 13922 Comm: syz-executor.3 Not tainted 5.8.0-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Call Trace:
__dump_stack lib/dump_stack.c:77 [inline]
dump_stack+0xf6/0x16e lib/dump_stack.c:118
print_address_description.constprop.0+0x1a/0x210 mm/kasan/report.c:383
__kasan_report mm/kasan/report.c:513 [inline]
kasan_report.cold+0x37/0x7c mm/kasan/report.c:530
usb_submit_urb+0x10c4/0x13e0 drivers/usb/core/urb.c:368
service_outstanding_interrupt.part.0+0x5f/0xa0 drivers/usb/class/cdc-wdm.c:463
service_outstanding_interrupt drivers/usb/class/cdc-wdm.c:458 [inline]
wdm_read+0x9a0/0xbd0 drivers/usb/class/cdc-wdm.c:576
vfs_read+0x1df/0x520 fs/read_write.c:479
ksys_read+0x12d/0x250 fs/read_write.c:607
do_syscall_64+0x2d/0x40 arch/x86/entry/common.c:46
entry_SYSCALL_64_after_hwframe+0x44/0xa9
RIP: 0033:0x45ce79
Code: 2d b6 fb ff c3 66 2e 0f 1f 84 00 00 00 00 00 66 90 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 0f 83 fb b5 fb ff c3 66 2e 0f 1f 84 00 00 00 00
RSP: 002b:00007f8d2099fc78 EFLAGS: 00000246 ORIG_RAX: 0000000000000000
RAX: ffffffffffffffda RBX: 00000000000252c0 RCX: 000000000045ce79
RDX: 00000000000000f2 RSI: 0000000020000100 RDI: 0000000000000003
RBP: 000000000118bf60 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 000000000118bf2c
R13: 00007ffd66f595ff R14: 00007f8d209a09c0 R15: 000000000118bf2c
Allocated by task 4524:
save_stack+0x1b/0x40 mm/kasan/common.c:48
set_track mm/kasan/common.c:56 [inline]
__kasan_kmalloc.constprop.0+0xc2/0xd0 mm/kasan/common.c:494
kmalloc include/linux/slab.h:555 [inline]
kzalloc include/linux/slab.h:669 [inline]
usb_alloc_dev+0x51/0xf67 drivers/usb/core/usb.c:582
hub_port_connect drivers/usb/core/hub.c:5114 [inline]
hub_port_connect_change drivers/usb/core/hub.c:5348 [inline]
port_event drivers/usb/core/hub.c:5494 [inline]
hub_event+0x1dff/0x4390 drivers/usb/core/hub.c:5576
process_one_work+0x94c/0x15f0 kernel/workqueue.c:2269
worker_thread+0x64c/0x1120 kernel/workqueue.c:2415
kthread+0x392/0x470 kernel/kthread.c:292
ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:294
Freed by task 5477:
save_stack+0x1b/0x40 mm/kasan/common.c:48
set_track mm/kasan/common.c:56 [inline]
kasan_set_free_info mm/kasan/common.c:316 [inline]
__kasan_slab_free+0x116/0x160 mm/kasan/common.c:455
slab_free_hook mm/slub.c:1474 [inline]
slab_free_freelist_hook+0x53/0x140 mm/slub.c:1507
slab_free mm/slub.c:3072 [inline]
kfree+0xbc/0x2c0 mm/slub.c:4052
device_release+0x71/0x200 drivers/base/core.c:1800
kobject_cleanup lib/kobject.c:704 [inline]
kobject_release lib/kobject.c:735 [inline]
kref_put include/linux/kref.h:65 [inline]
kobject_put+0x1c8/0x540 lib/kobject.c:752
put_device+0x1b/0x30 drivers/base/core.c:3029
hub_port_connect drivers/usb/core/hub.c:5059 [inline]
hub_port_connect_change drivers/usb/core/hub.c:5348 [inline]
port_event drivers/usb/core/hub.c:5494 [inline]
hub_event+0x1c93/0x4390 drivers/usb/core/hub.c:5576
process_one_work+0x94c/0x15f0 kernel/workqueue.c:2269
worker_thread+0x64c/0x1120 kernel/workqueue.c:2415
kthread+0x392/0x470 kernel/kthread.c:292
ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:294
The buggy address belongs to the object at ffff8881caa52000
which belongs to the cache kmalloc-2k of size 2048
The buggy address is located 24 bytes inside of
2048-byte region [ffff8881caa52000, ffff8881caa52800)
The buggy address belongs to the page:
page:ffffea00072a9400 refcount:1 mapcount:0 mapping:0000000000000000 index:0x0 head:ffffea00072a9400 order:3 compound_mapcount:0 compound_pincount:0
flags: 0x200000000010200(slab|head)
raw: 0200000000010200 0000000000000000 0000000100000001 ffff8881da00c000
raw: 0000000000000000 0000000000080008 00000001ffffffff 0000000000000000
page dumped because: kasan: bad access detected
Memory state around the buggy address:
ffff8881caa51f00: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
ffff8881caa51f80: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
>ffff8881caa52000: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
^
ffff8881caa52080: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
ffff8881caa52100: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
==================================================================
---
This report 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 issue. See:
https://goo.gl/tpsmEJ#status for how to communicate with syzbot.
syzbot has found a reproducer for the following issue on:
HEAD commit: 5e60366d Merge tag 'fallthrough-fixes-clang-5.11-rc1' of g..
git tree: https://git.kernel.org/pub/scm/linux/kernel/git/gregkh/usb.git usb-testing
console output: https://syzkaller.appspot.com/x/log.txt?x=12c5b623500000
kernel config: https://syzkaller.appspot.com/x/.config?x=5cea7506b7139727
dashboard link: https://syzkaller.appspot.com/bug?extid=9e04e2df4a32fb661daf
compiler: gcc (GCC) 10.1.0-syz 20200507
syz repro: https://syzkaller.appspot.com/x/repro.syz?x=175adf07500000
C reproducer: https://syzkaller.appspot.com/x/repro.c?x=1672680f500000
IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: [email protected]
==================================================================
BUG: KASAN: use-after-free in usb_submit_urb+0x1210/0x1560 drivers/usb/core/urb.c:383
Read of size 4 at addr ffff888101d21018 by task syz-executor166/4405
CPU: 0 PID: 4405 Comm: syz-executor166 Not tainted 5.10.0-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Call Trace:
__dump_stack lib/dump_stack.c:79 [inline]
dump_stack+0x107/0x163 lib/dump_stack.c:120
print_address_description.constprop.0.cold+0xae/0x4c8 mm/kasan/report.c:385
__kasan_report mm/kasan/report.c:545 [inline]
kasan_report.cold+0x1f/0x37 mm/kasan/report.c:562
usb_submit_urb+0x1210/0x1560 drivers/usb/core/urb.c:383
service_outstanding_interrupt.part.0+0x5f/0xa0 drivers/usb/class/cdc-wdm.c:470
service_outstanding_interrupt drivers/usb/class/cdc-wdm.c:465 [inline]
wdm_read+0x9a0/0xbd0 drivers/usb/class/cdc-wdm.c:583
vfs_read+0x1b5/0x570 fs/read_write.c:494
ksys_read+0x12d/0x250 fs/read_write.c:634
do_syscall_64+0x2d/0x40 arch/x86/entry/common.c:46
entry_SYSCALL_64_after_hwframe+0x44/0xa9
RIP: 0033:0x44b529
Code: e8 bc b4 02 00 48 83 c4 18 c3 0f 1f 80 00 00 00 00 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 0f 83 8b cb fb ff c3 66 2e 0f 1f 84 00 00 00 00
RSP: 002b:00007f2dfcb6ed98 EFLAGS: 00000246 ORIG_RAX: 0000000000000000
RAX: ffffffffffffffda RBX: 00000000006dcc38 RCX: 000000000044b529
RDX: 0000000000001000 RSI: 0000000020001000 RDI: 0000000000000004
RBP: 00000000006dcc30 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 00000000006dcc3c
R13: 0142006002090100 R14: 04010040a4157d25 R15: 4000000200000112
Allocated by task 2632:
kasan_save_stack+0x1b/0x40 mm/kasan/common.c:48
kasan_set_track mm/kasan/common.c:56 [inline]
__kasan_kmalloc.constprop.0+0xc2/0xd0 mm/kasan/common.c:461
kmalloc include/linux/slab.h:552 [inline]
kzalloc include/linux/slab.h:682 [inline]
usb_alloc_dev+0x51/0xef0 drivers/usb/core/usb.c:582
hub_port_connect drivers/usb/core/hub.c:5129 [inline]
hub_port_connect_change drivers/usb/core/hub.c:5363 [inline]
port_event drivers/usb/core/hub.c:5509 [inline]
hub_event+0x1def/0x42d0 drivers/usb/core/hub.c:5591
process_one_work+0x98d/0x15c0 kernel/workqueue.c:2275
worker_thread+0x64c/0x1120 kernel/workqueue.c:2421
kthread+0x38c/0x460 kernel/kthread.c:292
ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:296
Freed by task 2181:
kasan_save_stack+0x1b/0x40 mm/kasan/common.c:48
kasan_set_track+0x1c/0x30 mm/kasan/common.c:56
kasan_set_free_info+0x1b/0x30 mm/kasan/generic.c:352
__kasan_slab_free+0x102/0x140 mm/kasan/common.c:422
slab_free_hook mm/slub.c:1544 [inline]
slab_free_freelist_hook+0x5d/0x150 mm/slub.c:1577
slab_free mm/slub.c:3140 [inline]
kfree+0xdb/0x3a0 mm/slub.c:4122
device_release+0x9f/0x240 drivers/base/core.c:1962
kobject_cleanup lib/kobject.c:705 [inline]
kobject_release lib/kobject.c:736 [inline]
kref_put include/linux/kref.h:65 [inline]
kobject_put+0x1c8/0x540 lib/kobject.c:753
put_device+0x1b/0x30 drivers/base/core.c:3190
hub_port_connect drivers/usb/core/hub.c:5074 [inline]
hub_port_connect_change drivers/usb/core/hub.c:5363 [inline]
port_event drivers/usb/core/hub.c:5509 [inline]
hub_event+0x1c8a/0x42d0 drivers/usb/core/hub.c:5591
process_one_work+0x98d/0x15c0 kernel/workqueue.c:2275
worker_thread+0x64c/0x1120 kernel/workqueue.c:2421
kthread+0x38c/0x460 kernel/kthread.c:292
ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:296
The buggy address belongs to the object at ffff888101d21000
which belongs to the cache kmalloc-2k of size 2048
The buggy address is located 24 bytes inside of
2048-byte region [ffff888101d21000, ffff888101d21800)
The buggy address belongs to the page:
page:0000000019761127 refcount:1 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x101d20
head:0000000019761127 order:3 compound_mapcount:0 compound_pincount:0
flags: 0x200000000010200(slab|head)
raw: 0200000000010200 dead000000000100 dead000000000122 ffff888100042000
raw: 0000000000000000 0000000080080008 00000001ffffffff 0000000000000000
page dumped because: kasan: bad access detected
Memory state around the buggy address:
ffff888101d20f00: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
ffff888101d20f80: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
>ffff888101d21000: fa fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
^
ffff888101d21080: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
ffff888101d21100: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
==================================================================
On Fri, Dec 18, 2020 at 04:21:13PM +0800, Hillf Danton wrote:
> On Thu, 17 Dec 2020 19:21:10 -0800
> > syzbot has found a reproducer for the following issue on:
> >
> > HEAD commit: 5e60366d Merge tag 'fallthrough-fixes-clang-5.11-rc1' of g..
> > git tree: https://git.kernel.org/pub/scm/linux/kernel/git/gregkh/usb.git usb-testing
> > console output: https://syzkaller.appspot.com/x/log.txt?x=12c5b623500000
> > kernel config: https://syzkaller.appspot.com/x/.config?x=5cea7506b7139727
> > dashboard link: https://syzkaller.appspot.com/bug?extid=9e04e2df4a32fb661daf
> > compiler: gcc (GCC) 10.1.0-syz 20200507
> > syz repro: https://syzkaller.appspot.com/x/repro.syz?x=175adf07500000
> > C reproducer: https://syzkaller.appspot.com/x/repro.c?x=1672680f500000
> >
> > IMPORTANT: if you fix the issue, please add the following tag to the commit:
> > Reported-by: [email protected]
> >
> > ==================================================================
> > BUG: KASAN: use-after-free in usb_submit_urb+0x1210/0x1560 drivers/usb/core/urb.c:383
> > Read of size 4 at addr ffff888101d21018 by task syz-executor166/4405
> >
> > CPU: 0 PID: 4405 Comm: syz-executor166 Not tainted 5.10.0-syzkaller #0
> > Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
> > Call Trace:
> > __dump_stack lib/dump_stack.c:79 [inline]
> > dump_stack+0x107/0x163 lib/dump_stack.c:120
> > print_address_description.constprop.0.cold+0xae/0x4c8 mm/kasan/report.c:385
> > __kasan_report mm/kasan/report.c:545 [inline]
> > kasan_report.cold+0x1f/0x37 mm/kasan/report.c:562
> > usb_submit_urb+0x1210/0x1560 drivers/usb/core/urb.c:383
> > service_outstanding_interrupt.part.0+0x5f/0xa0 drivers/usb/class/cdc-wdm.c:470
> > service_outstanding_interrupt drivers/usb/class/cdc-wdm.c:465 [inline]
> > wdm_read+0x9a0/0xbd0 drivers/usb/class/cdc-wdm.c:583
> > vfs_read+0x1b5/0x570 fs/read_write.c:494
> > ksys_read+0x12d/0x250 fs/read_write.c:634
> > do_syscall_64+0x2d/0x40 arch/x86/entry/common.c:46
> > entry_SYSCALL_64_after_hwframe+0x44/0xa9
> > RIP: 0033:0x44b529
> > Code: e8 bc b4 02 00 48 83 c4 18 c3 0f 1f 80 00 00 00 00 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 0f 83 8b cb fb ff c3 66 2e 0f 1f 84 00 00 00 00
> > RSP: 002b:00007f2dfcb6ed98 EFLAGS: 00000246 ORIG_RAX: 0000000000000000
> > RAX: ffffffffffffffda RBX: 00000000006dcc38 RCX: 000000000044b529
> > RDX: 0000000000001000 RSI: 0000000020001000 RDI: 0000000000000004
> > RBP: 00000000006dcc30 R08: 0000000000000000 R09: 0000000000000000
> > R10: 0000000000000000 R11: 0000000000000246 R12: 00000000006dcc3c
> > R13: 0142006002090100 R14: 04010040a4157d25 R15: 4000000200000112
> >
> > Allocated by task 2632:
> > kasan_save_stack+0x1b/0x40 mm/kasan/common.c:48
> > kasan_set_track mm/kasan/common.c:56 [inline]
> > __kasan_kmalloc.constprop.0+0xc2/0xd0 mm/kasan/common.c:461
> > kmalloc include/linux/slab.h:552 [inline]
> > kzalloc include/linux/slab.h:682 [inline]
> > usb_alloc_dev+0x51/0xef0 drivers/usb/core/usb.c:582
> > hub_port_connect drivers/usb/core/hub.c:5129 [inline]
> > hub_port_connect_change drivers/usb/core/hub.c:5363 [inline]
> > port_event drivers/usb/core/hub.c:5509 [inline]
> > hub_event+0x1def/0x42d0 drivers/usb/core/hub.c:5591
> > process_one_work+0x98d/0x15c0 kernel/workqueue.c:2275
> > worker_thread+0x64c/0x1120 kernel/workqueue.c:2421
> > kthread+0x38c/0x460 kernel/kthread.c:292
> > ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:296
> >
> > Freed by task 2181:
> > kasan_save_stack+0x1b/0x40 mm/kasan/common.c:48
> > kasan_set_track+0x1c/0x30 mm/kasan/common.c:56
> > kasan_set_free_info+0x1b/0x30 mm/kasan/generic.c:352
> > __kasan_slab_free+0x102/0x140 mm/kasan/common.c:422
> > slab_free_hook mm/slub.c:1544 [inline]
> > slab_free_freelist_hook+0x5d/0x150 mm/slub.c:1577
> > slab_free mm/slub.c:3140 [inline]
> > kfree+0xdb/0x3a0 mm/slub.c:4122
> > device_release+0x9f/0x240 drivers/base/core.c:1962
> > kobject_cleanup lib/kobject.c:705 [inline]
> > kobject_release lib/kobject.c:736 [inline]
> > kref_put include/linux/kref.h:65 [inline]
> > kobject_put+0x1c8/0x540 lib/kobject.c:753
> > put_device+0x1b/0x30 drivers/base/core.c:3190
> > hub_port_connect drivers/usb/core/hub.c:5074 [inline]
> > hub_port_connect_change drivers/usb/core/hub.c:5363 [inline]
> > port_event drivers/usb/core/hub.c:5509 [inline]
> > hub_event+0x1c8a/0x42d0 drivers/usb/core/hub.c:5591
> > process_one_work+0x98d/0x15c0 kernel/workqueue.c:2275
> > worker_thread+0x64c/0x1120 kernel/workqueue.c:2421
> > kthread+0x38c/0x460 kernel/kthread.c:292
> > ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:296
> >
> > The buggy address belongs to the object at ffff888101d21000
> > which belongs to the cache kmalloc-2k of size 2048
> > The buggy address is located 24 bytes inside of
> > 2048-byte region [ffff888101d21000, ffff888101d21800)
> > The buggy address belongs to the page:
> > page:0000000019761127 refcount:1 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x101d20
> > head:0000000019761127 order:3 compound_mapcount:0 compound_pincount:0
> > flags: 0x200000000010200(slab|head)
> > raw: 0200000000010200 dead000000000100 dead000000000122 ffff888100042000
> > raw: 0000000000000000 0000000080080008 00000001ffffffff 0000000000000000
> > page dumped because: kasan: bad access detected
> >
> > Memory state around the buggy address:
> > ffff888101d20f00: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
> > ffff888101d20f80: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
> > >ffff888101d21000: fa fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
> > ^
> > ffff888101d21080: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
> > ffff888101d21100: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
> > ==================================================================
> >
> Bail out without urb submitted if wdm device is disconnecting.
>
> --- a/drivers/usb/class/cdc-wdm.c
> +++ b/drivers/usb/class/cdc-wdm.c
> @@ -474,18 +474,25 @@ out:
> return rv;
> }
>
> -static ssize_t wdm_read
> -(struct file *file, char __user *buffer, size_t count, loff_t *ppos)
> +static ssize_t wdm_read(struct file *file, char __user *buffer,
> + size_t count, loff_t *ppos)
> {
> int rv, cntr;
> int i = 0;
> struct wdm_device *desc = file->private_data;
>
> + if (test_bit(WDM_DISCONNECTING, &desc->flags))
> + return -ENODEV;
>
> rv = mutex_lock_interruptible(&desc->rlock); /*concurrent reads */
> if (rv < 0)
> return -ERESTARTSYS;
>
> + if (test_bit(WDM_DISCONNECTING, &desc->flags)) {
> + rv = -ENODEV;
> + goto err;
> + }
Why test before the lock if you test right after the lock?
and what happens if the bit is set right _after_ you test this?
thanks,
greg k-h
On Fri, Dec 18, 2020 at 06:01:34PM +0800, Hillf Danton wrote:
> On Fri, 18 Dec 2020 09:28:16 +0100 Greg KH wrote:
> >On Fri, Dec 18, 2020 at 04:21:13PM +0800, Hillf Danton wrote:
> >> On Thu, 17 Dec 2020 19:21:10 -0800
> >> > syzbot has found a reproducer for the following issue on:
> >> >
> >> > HEAD commit: 5e60366d Merge tag 'fallthrough-fixes-clang-5.11-rc1' of g..
> >> > git tree: https://git.kernel.org/pub/scm/linux/kernel/git/gregkh/usb.git usb-testing
> >> > console output: https://syzkaller.appspot.com/x/log.txt?x=12c5b623500000
> >> > kernel config: https://syzkaller.appspot.com/x/.config?x=5cea7506b7139727
> >> > dashboard link: https://syzkaller.appspot.com/bug?extid=9e04e2df4a32fb661daf
> >> > compiler: gcc (GCC) 10.1.0-syz 20200507
> >> > syz repro: https://syzkaller.appspot.com/x/repro.syz?x=175adf07500000
> >> > C reproducer: https://syzkaller.appspot.com/x/repro.c?x=1672680f500000
> >> >
> >> > IMPORTANT: if you fix the issue, please add the following tag to the commit:
> >> > Reported-by: [email protected]
> >> >
> >> > ==================================================================
> >> > BUG: KASAN: use-after-free in usb_submit_urb+0x1210/0x1560 drivers/usb/core/urb.c:383
> >> > Read of size 4 at addr ffff888101d21018 by task syz-executor166/4405
> >> >
> >> > CPU: 0 PID: 4405 Comm: syz-executor166 Not tainted 5.10.0-syzkaller #0
> >> > Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
> >> > Call Trace:
> >> > __dump_stack lib/dump_stack.c:79 [inline]
> >> > dump_stack+0x107/0x163 lib/dump_stack.c:120
> >> > print_address_description.constprop.0.cold+0xae/0x4c8 mm/kasan/report.c:385
> >> > __kasan_report mm/kasan/report.c:545 [inline]
> >> > kasan_report.cold+0x1f/0x37 mm/kasan/report.c:562
> >> > usb_submit_urb+0x1210/0x1560 drivers/usb/core/urb.c:383
> >> > service_outstanding_interrupt.part.0+0x5f/0xa0 drivers/usb/class/cdc-wdm.c:470
> >> > service_outstanding_interrupt drivers/usb/class/cdc-wdm.c:465 [inline]
> >> > wdm_read+0x9a0/0xbd0 drivers/usb/class/cdc-wdm.c:583
> >> > vfs_read+0x1b5/0x570 fs/read_write.c:494
> >> > ksys_read+0x12d/0x250 fs/read_write.c:634
> >> > do_syscall_64+0x2d/0x40 arch/x86/entry/common.c:46
> >> > entry_SYSCALL_64_after_hwframe+0x44/0xa9
> >> > RIP: 0033:0x44b529
> >> > Code: e8 bc b4 02 00 48 83 c4 18 c3 0f 1f 80 00 00 00 00 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 0f 83 8b cb fb ff c3 66 2e 0f 1f 84 00 00 00 00
> >> > RSP: 002b:00007f2dfcb6ed98 EFLAGS: 00000246 ORIG_RAX: 0000000000000000
> >> > RAX: ffffffffffffffda RBX: 00000000006dcc38 RCX: 000000000044b529
> >> > RDX: 0000000000001000 RSI: 0000000020001000 RDI: 0000000000000004
> >> > RBP: 00000000006dcc30 R08: 0000000000000000 R09: 0000000000000000
> >> > R10: 0000000000000000 R11: 0000000000000246 R12: 00000000006dcc3c
> >> > R13: 0142006002090100 R14: 04010040a4157d25 R15: 4000000200000112
> >> >
> >> > Allocated by task 2632:
> >> > kasan_save_stack+0x1b/0x40 mm/kasan/common.c:48
> >> > kasan_set_track mm/kasan/common.c:56 [inline]
> >> > __kasan_kmalloc.constprop.0+0xc2/0xd0 mm/kasan/common.c:461
> >> > kmalloc include/linux/slab.h:552 [inline]
> >> > kzalloc include/linux/slab.h:682 [inline]
> >> > usb_alloc_dev+0x51/0xef0 drivers/usb/core/usb.c:582
> >> > hub_port_connect drivers/usb/core/hub.c:5129 [inline]
> >> > hub_port_connect_change drivers/usb/core/hub.c:5363 [inline]
> >> > port_event drivers/usb/core/hub.c:5509 [inline]
> >> > hub_event+0x1def/0x42d0 drivers/usb/core/hub.c:5591
> >> > process_one_work+0x98d/0x15c0 kernel/workqueue.c:2275
> >> > worker_thread+0x64c/0x1120 kernel/workqueue.c:2421
> >> > kthread+0x38c/0x460 kernel/kthread.c:292
> >> > ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:296
> >> >
> >> > Freed by task 2181:
> >> > kasan_save_stack+0x1b/0x40 mm/kasan/common.c:48
> >> > kasan_set_track+0x1c/0x30 mm/kasan/common.c:56
> >> > kasan_set_free_info+0x1b/0x30 mm/kasan/generic.c:352
> >> > __kasan_slab_free+0x102/0x140 mm/kasan/common.c:422
> >> > slab_free_hook mm/slub.c:1544 [inline]
> >> > slab_free_freelist_hook+0x5d/0x150 mm/slub.c:1577
> >> > slab_free mm/slub.c:3140 [inline]
> >> > kfree+0xdb/0x3a0 mm/slub.c:4122
> >> > device_release+0x9f/0x240 drivers/base/core.c:1962
> >> > kobject_cleanup lib/kobject.c:705 [inline]
> >> > kobject_release lib/kobject.c:736 [inline]
> >> > kref_put include/linux/kref.h:65 [inline]
> >> > kobject_put+0x1c8/0x540 lib/kobject.c:753
> >> > put_device+0x1b/0x30 drivers/base/core.c:3190
> >> > hub_port_connect drivers/usb/core/hub.c:5074 [inline]
> >> > hub_port_connect_change drivers/usb/core/hub.c:5363 [inline]
> >> > port_event drivers/usb/core/hub.c:5509 [inline]
> >> > hub_event+0x1c8a/0x42d0 drivers/usb/core/hub.c:5591
> >> > process_one_work+0x98d/0x15c0 kernel/workqueue.c:2275
> >> > worker_thread+0x64c/0x1120 kernel/workqueue.c:2421
> >> > kthread+0x38c/0x460 kernel/kthread.c:292
> >> > ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:296
> >> >
> >> > The buggy address belongs to the object at ffff888101d21000
> >> > which belongs to the cache kmalloc-2k of size 2048
> >> > The buggy address is located 24 bytes inside of
> >> > 2048-byte region [ffff888101d21000, ffff888101d21800)
> >> > The buggy address belongs to the page:
> >> > page:0000000019761127 refcount:1 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x101d20
> >> > head:0000000019761127 order:3 compound_mapcount:0 compound_pincount:0
> >> > flags: 0x200000000010200(slab|head)
> >> > raw: 0200000000010200 dead000000000100 dead000000000122 ffff888100042000
> >> > raw: 0000000000000000 0000000080080008 00000001ffffffff 0000000000000000
> >> > page dumped because: kasan: bad access detected
> >> >
> >> > Memory state around the buggy address:
> >> > ffff888101d20f00: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
> >> > ffff888101d20f80: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
> >> > >ffff888101d21000: fa fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
> >> > ^
> >> > ffff888101d21080: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
> >> > ffff888101d21100: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
> >> > ==================================================================
> >> >
> >> Bail out without urb submitted if wdm device is disconnecting.
> >>
> >> --- a/drivers/usb/class/cdc-wdm.c
> >> +++ b/drivers/usb/class/cdc-wdm.c
> >> @@ -474,18 +474,25 @@ out:
> >> return rv;
> >> }
> >>
> >> -static ssize_t wdm_read
> >> -(struct file *file, char __user *buffer, size_t count, loff_t *ppos)
> >> +static ssize_t wdm_read(struct file *file, char __user *buffer,
> >> + size_t count, loff_t *ppos)
> >> {
> >> int rv, cntr;
> >> int i = 0;
> >> struct wdm_device *desc = file->private_data;
> >>
> >> + if (test_bit(WDM_DISCONNECTING, &desc->flags))
> >> + return -ENODEV;
> >>
> >> rv = mutex_lock_interruptible(&desc->rlock); /*concurrent reads */
> >> if (rv < 0)
> >> return -ERESTARTSYS;
> >>
> >> + if (test_bit(WDM_DISCONNECTING, &desc->flags)) {
> >> + rv = -ENODEV;
> >> + goto err;
> >> + }
> >
> >Why test before the lock if you test right after the lock?
>
> Any test is supposed to make sense.
I do not understand.
I am trying to say, why do you even have the test outside of the lock as
that makes no sense?
> >and what happens if the bit is set right _after_ you test this?
>
> Your question explains the above double test.
No it doesn't :)
> If we get desc->rlock and fail to test WDM_DISCONNECTING in the
> read path then we are safe because the same lock is acquired also
> in the disconnect path.
Then only check the bit _when_ the lock is held. Otherwise it is a
pointless check.
thanks,
greg k-h
Am Donnerstag, den 17.12.2020, 19:21 -0800 schrieb syzbot:
> syzbot has found a reproducer for the following issue on:
>
> HEAD commit: 5e60366d Merge tag 'fallthrough-fixes-clang-5.11-rc1' of g..
> git tree: https://git.kernel.org/pub/scm/linux/kernel/git/gregkh/usb.git usb-testing
> console output: https://syzkaller.appspot.com/x/log.txt?x=12c5b623500000
> kernel config: https://syzkaller.appspot.com/x/.config?x=5cea7506b7139727
> dashboard link: https://syzkaller.appspot.com/bug?extid=9e04e2df4a32fb661daf
> compiler: gcc (GCC) 10.1.0-syz 20200507
> syz repro: https://syzkaller.appspot.com/x/repro.syz?x=175adf07500000
> C reproducer: https://syzkaller.appspot.com/x/repro.c?x=1672680f500000
>
> IMPORTANT: if you fix the issue, please add the following tag to the commit:
> Reported-by: [email protected]
#syz test: https://github.com/google/kasan.git 5e60366d
From f51e3c5a202f3abc805edd64b21a68d29dd9d60e Mon Sep 17 00:00:00 2001
From: Oliver Neukum <[email protected]>
Date: Mon, 4 Jan 2021 17:26:33 +0100
Subject: [PATCH] cdc-wdm: poison URBs upon disconnect
We have a chicken and egg issue between interrupt and work.
This should break the cycle.
Signed-off-by: Oliver Neukum <[email protected]>
---
drivers/usb/class/cdc-wdm.c | 6 +++---
1 file changed, 3 insertions(+), 3 deletions(-)
diff --git a/drivers/usb/class/cdc-wdm.c b/drivers/usb/class/cdc-wdm.c
index 02d0cfd23bb2..14eddda35280 100644
--- a/drivers/usb/class/cdc-wdm.c
+++ b/drivers/usb/class/cdc-wdm.c
@@ -324,9 +324,9 @@ static void wdm_int_callback(struct urb *urb)
static void kill_urbs(struct wdm_device *desc)
{
/* the order here is essential */
- usb_kill_urb(desc->command);
- usb_kill_urb(desc->validity);
- usb_kill_urb(desc->response);
+ usb_poison_urb(desc->command);
+ usb_poison_urb(desc->validity);
+ usb_poison_urb(desc->response);
}
static void free_urbs(struct wdm_device *desc)
--
2.26.2
Hello,
syzbot has tested the proposed patch but the reproducer is still triggering an issue:
KASAN: use-after-free Read in service_outstanding_interrupt
==================================================================
BUG: KASAN: use-after-free in usb_submit_urb+0x1210/0x1560 drivers/usb/core/urb.c:383
Read of size 4 at addr ffff888113e9f018 by task syz-executor.0/7799
CPU: 1 PID: 7799 Comm: syz-executor.0 Not tainted 5.10.0-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Call Trace:
__dump_stack lib/dump_stack.c:79 [inline]
dump_stack+0x107/0x163 lib/dump_stack.c:120
print_address_description.constprop.0.cold+0xae/0x4c8 mm/kasan/report.c:385
__kasan_report mm/kasan/report.c:545 [inline]
kasan_report.cold+0x1f/0x37 mm/kasan/report.c:562
usb_submit_urb+0x1210/0x1560 drivers/usb/core/urb.c:383
service_outstanding_interrupt.part.0+0x5f/0xa0 drivers/usb/class/cdc-wdm.c:470
service_outstanding_interrupt drivers/usb/class/cdc-wdm.c:465 [inline]
wdm_read+0x9a0/0xbd0 drivers/usb/class/cdc-wdm.c:583
vfs_read+0x1b5/0x570 fs/read_write.c:494
ksys_read+0x12d/0x250 fs/read_write.c:634
do_syscall_64+0x2d/0x40 arch/x86/entry/common.c:46
entry_SYSCALL_64_after_hwframe+0x44/0xa9
RIP: 0033:0x45e149
Code: 0d b4 fb ff c3 66 2e 0f 1f 84 00 00 00 00 00 66 90 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 0f 83 db b3 fb ff c3 66 2e 0f 1f 84 00 00 00 00
RSP: 002b:00007fcce8099c68 EFLAGS: 00000246 ORIG_RAX: 0000000000000000
RAX: ffffffffffffffda RBX: 0000000000000003 RCX: 000000000045e149
RDX: 0000000000001000 RSI: 0000000020001000 RDI: 0000000000000004
RBP: 000000000119c068 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 000000000119c034
R13: 00007fffc13967df R14: 00007fcce809a9c0 R15: 000000000119c034
Allocated by task 17:
kasan_save_stack+0x1b/0x40 mm/kasan/common.c:48
kasan_set_track mm/kasan/common.c:56 [inline]
__kasan_kmalloc.constprop.0+0xc2/0xd0 mm/kasan/common.c:461
kmalloc include/linux/slab.h:552 [inline]
kzalloc include/linux/slab.h:682 [inline]
usb_alloc_dev+0x51/0xef0 drivers/usb/core/usb.c:582
hub_port_connect drivers/usb/core/hub.c:5129 [inline]
hub_port_connect_change drivers/usb/core/hub.c:5363 [inline]
port_event drivers/usb/core/hub.c:5509 [inline]
hub_event+0x1def/0x42d0 drivers/usb/core/hub.c:5591
process_one_work+0x98d/0x15c0 kernel/workqueue.c:2275
worker_thread+0x64c/0x1120 kernel/workqueue.c:2421
kthread+0x38c/0x460 kernel/kthread.c:292
ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:296
Freed by task 2183:
kasan_save_stack+0x1b/0x40 mm/kasan/common.c:48
kasan_set_track+0x1c/0x30 mm/kasan/common.c:56
kasan_set_free_info+0x1b/0x30 mm/kasan/generic.c:352
__kasan_slab_free+0x102/0x140 mm/kasan/common.c:422
slab_free_hook mm/slub.c:1544 [inline]
slab_free_freelist_hook+0x5d/0x150 mm/slub.c:1577
slab_free mm/slub.c:3140 [inline]
kfree+0xdb/0x3a0 mm/slub.c:4122
device_release+0x9f/0x240 drivers/base/core.c:1962
kobject_cleanup lib/kobject.c:705 [inline]
kobject_release lib/kobject.c:736 [inline]
kref_put include/linux/kref.h:65 [inline]
kobject_put+0x1c8/0x540 lib/kobject.c:753
put_device+0x1b/0x30 drivers/base/core.c:3190
hub_port_connect drivers/usb/core/hub.c:5074 [inline]
hub_port_connect_change drivers/usb/core/hub.c:5363 [inline]
port_event drivers/usb/core/hub.c:5509 [inline]
hub_event+0x1c8a/0x42d0 drivers/usb/core/hub.c:5591
process_one_work+0x98d/0x15c0 kernel/workqueue.c:2275
worker_thread+0x64c/0x1120 kernel/workqueue.c:2421
kthread+0x38c/0x460 kernel/kthread.c:292
ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:296
Last potentially related work creation:
kasan_save_stack+0x1b/0x40 mm/kasan/common.c:48
kasan_record_aux_stack+0xc0/0xf0 mm/kasan/generic.c:343
insert_work+0x48/0x370 kernel/workqueue.c:1331
__queue_work+0x5c3/0xf60 kernel/workqueue.c:1497
queue_work_on+0xc7/0xd0 kernel/workqueue.c:1524
kref_put include/linux/kref.h:65 [inline]
tty_kref_put drivers/tty/tty_io.c:1493 [inline]
release_tty+0x4e9/0x610 drivers/tty/tty_io.c:1530
tty_release_struct+0xb4/0xe0 drivers/tty/tty_io.c:1629
tty_release+0xc70/0x1210 drivers/tty/tty_io.c:1789
__fput+0x288/0x920 fs/file_table.c:280
task_work_run+0xdd/0x1a0 kernel/task_work.c:168
tracehook_notify_resume include/linux/tracehook.h:189 [inline]
exit_to_user_mode_loop kernel/entry/common.c:174 [inline]
exit_to_user_mode_prepare+0x186/0x190 kernel/entry/common.c:201
__syscall_exit_to_user_mode_work kernel/entry/common.c:291 [inline]
syscall_exit_to_user_mode+0x19/0x50 kernel/entry/common.c:302
entry_SYSCALL_64_after_hwframe+0x44/0xa9
The buggy address belongs to the object at ffff888113e9f000
which belongs to the cache kmalloc-2k of size 2048
The buggy address is located 24 bytes inside of
2048-byte region [ffff888113e9f000, ffff888113e9f800)
The buggy address belongs to the page:
page:00000000e5a7bd64 refcount:1 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x113e98
head:00000000e5a7bd64 order:3 compound_mapcount:0 compound_pincount:0
flags: 0x200000000010200(slab|head)
raw: 0200000000010200 dead000000000100 dead000000000122 ffff888100042000
raw: 0000000000000000 0000000000080008 00000001ffffffff 0000000000000000
page dumped because: kasan: bad access detected
Memory state around the buggy address:
ffff888113e9ef00: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
ffff888113e9ef80: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
>ffff888113e9f000: fa fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
^
ffff888113e9f080: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
ffff888113e9f100: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
==================================================================
Tested on:
commit: 5e60366d Merge tag 'fallthrough-fixes-clang-5.11-rc1' of g..
git tree: https://github.com/google/kasan.git
console output: https://syzkaller.appspot.com/x/log.txt?x=1755d077500000
kernel config: https://syzkaller.appspot.com/x/.config?x=5cea7506b7139727
dashboard link: https://syzkaller.appspot.com/bug?extid=9e04e2df4a32fb661daf
compiler: gcc (GCC) 10.1.0-syz 20200507
patch: https://syzkaller.appspot.com/x/patch.diff?x=15e05e57500000
________________________________________
??????: Oliver Neukum <[email protected]>
????ʱ??: 2021??1??5?? 0:28
?ռ???: syzbot; [email protected]; [email protected]; [email protected]; [email protected]; [email protected]; [email protected]; [email protected]; [email protected]; [email protected]
????: Re: KASAN: use-after-free Read in service_outstanding_interrupt
Am Donnerstag, den 17.12.2020, 19:21 -0800 schrieb syzbot:
> syzbot has found a reproducer for the following issue on:
>
> HEAD commit: 5e60366d Merge tag 'fallthrough-fixes-clang-5.11-rc1' of g..
> git tree: https://git.kernel.org/pub/scm/linux/kernel/git/gregkh/usb.git usb-testing
> console output: https://syzkaller.appspot.com/x/log.txt?x=12c5b623500000
> kernel config: https://syzkaller.appspot.com/x/.config?x=5cea7506b7139727
> dashboard link: https://syzkaller.appspot.com/bug?extid=9e04e2df4a32fb661daf
> compiler: gcc (GCC) 10.1.0-syz 20200507
> syz repro: https://syzkaller.appspot.com/x/repro.syz?x=175adf07500000
> C reproducer: https://syzkaller.appspot.com/x/repro.c?x=1672680f500000
>
> IMPORTANT: if you fix the issue, please add the following tag to the commit:
> Reported-by: >[email protected]
>
>#syz test: https://github.com/google/kasan.git 5e60366d
>
Hello Oliver
this use-after-free still exists??It can be seen from calltrace that it is
usb_device's object has been released when disconnect,
can add a reference count to usb_device's object to avoid this problem
diff --git a/drivers/usb/class/cdc-wdm.c b/drivers/usb/class/cdc-wdm.c
index 508b1c3f8b73..001cb93da6bf 100644
--- a/drivers/usb/class/cdc-wdm.c
+++ b/drivers/usb/class/cdc-wdm.c
@@ -106,6 +106,7 @@ struct wdm_device {
struct list_head device_list;
int (*manage_power)(struct usb_interface *, int);
+ struct usb_device *usb_dev;
};
static struct usb_driver wdm_driver;
@@ -338,6 +339,7 @@ static void free_urbs(struct wdm_device *desc)
static void cleanup(struct wdm_device *desc)
{
+ usb_put_dev(desc->usb_dev);
kfree(desc->sbuf);
kfree(desc->inbuf);
kfree(desc->orq);
@@ -855,6 +857,7 @@ static int wdm_create(struct usb_interface *intf, struct usb_endpoint_descripto
r
desc->intf = intf;
INIT_WORK(&desc->rxwork, wdm_rxwork);
INIT_WORK(&desc->service_outs_intr, service_interrupt_work);
+ desc->usb_dev = usb_get_dev(interface_to_usbdev(intf));
rv = -EINVAL;
if (!usb_endpoint_is_int_in(ep))
>From f51e3c5a202f3abc805edd64b21a68d29dd9d60e Mon Sep 17 >00:00:00 2001
>From: Oliver Neukum <[email protected]>
>Date: Mon, 4 Jan 2021 17:26:33 +0100
>Subject: [PATCH] cdc-wdm: poison URBs upon disconnect
>
>We have a chicken and egg issue between interrupt and work.
>This should break the cycle.
>
>Signed-off-by: Oliver Neukum <[email protected]>
>---
>drivers/usb/class/cdc-wdm.c | 6 +++---
> 1 file changed, 3 insertions(+), 3 deletions(-)
>
>diff --git a/drivers/usb/class/cdc-wdm.c b/drivers/usb/class/cdc->wdm.c
>index 02d0cfd23bb2..14eddda35280 100644
>--- a/drivers/usb/class/cdc-wdm.c
>+++ b/drivers/usb/class/cdc-wdm.c
>@@ -324,9 +324,9 @@ static void wdm_int_callback(struct urb *urb)
>static void kill_urbs(struct wdm_device *desc)
> {
> /* the order here is essential */
>- usb_kill_urb(desc->command);
>- usb_kill_urb(desc->validity);
>- usb_kill_urb(desc->response);
>+ usb_poison_urb(desc->command);
>+ usb_poison_urb(desc->validity);
>+ usb_poison_urb(desc->response);
> }
>
> static void free_urbs(struct wdm_device *desc)
>--
>2.26.2
Am Dienstag, den 05.01.2021, 04:50 +0000 schrieb Zhang, Qiang:
>
> ________________________________________
> 发件人: Oliver Neukum <[email protected]>
> 发送时间: 2021年1月5日 0:28
> 收件人: syzbot; [email protected]; [email protected]; [email protected]; [email protected]; [email protected]; [email protected]; [email protected]; [email protected]; [email protected]
> 主题: Re: KASAN: use-after-free Read in service_outstanding_interrupt
>
> Am Donnerstag, den 17.12.2020, 19:21 -0800 schrieb syzbot:
> > syzbot has found a reproducer for the following issue on:
> >
> > HEAD commit: 5e60366d Merge tag 'fallthrough-fixes-clang-5.11-rc1' of g..
> > git tree: https://git.kernel.org/pub/scm/linux/kernel/git/gregkh/usb.git usb-testing
> > console output: https://syzkaller.appspot.com/x/log.txt?x=12c5b623500000
> > kernel config: https://syzkaller.appspot.com/x/.config?x=5cea7506b7139727
> > dashboard link: https://syzkaller.appspot.com/bug?extid=9e04e2df4a32fb661daf
> > compiler: gcc (GCC) 10.1.0-syz 20200507
> > syz repro: https://syzkaller.appspot.com/x/repro.syz?x=175adf07500000
> > C reproducer: https://syzkaller.appspot.com/x/repro.c?x=1672680f500000
> >
> > IMPORTANT: if you fix the issue, please add the following tag to the commit:
> > Reported-by: >[email protected]
> >
> > #syz test: https://github.com/google/kasan.git 5e60366d
> >
>
> Hello Oliver
>
> this use-after-free still exists，It can be seen from calltrace that it is
> usb_device's object has been released when disconnect,
> can add a reference count to usb_device's object to avoid this problem
Hi,
thanks for your analysis. I think you are correct in your analysis, but
I am afraid your fix is not correct. The driver is submitting an URB
to a disconnected device. Your fix would prevent a crash, which is
definitely good, but we still cannot do that, because the device may
be owned by another driver or usbfs at that time.
Regards
Oliver