Hello,
syzbot found the following crash on:
HEAD commit: 0bddd227 Documentation: update for gcc 4.9 requirement
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=1418afb7100000
kernel config: https://syzkaller.appspot.com/x/.config?x=66ad203c2bb6d8b
dashboard link: https://syzkaller.appspot.com/bug?extid=20b90969babe05609947
compiler: gcc (GCC) 10.1.0-syz 20200507
syz repro: https://syzkaller.appspot.com/x/repro.syz?x=12a8edff100000
C reproducer: https://syzkaller.appspot.com/x/repro.c?x=167d3bb7100000
IMPORTANT: if you fix the bug, please add the following tag to the commit:
Reported-by: [email protected]
==================================================================
BUG: KASAN: use-after-free in dev_put include/linux/netdevice.h:3853 [inline]
BUG: KASAN: use-after-free in netdevice_event_work_handler+0x15b/0x1b0 drivers/infiniband/core/roce_gid_mgmt.c:627
Read of size 8 at addr ffff88807b13e568 by task kworker/u4:0/7
CPU: 0 PID: 7 Comm: kworker/u4:0 Not tainted 5.8.0-rc4-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Workqueue: gid-cache-wq netdevice_event_work_handler
Call Trace:
__dump_stack lib/dump_stack.c:77 [inline]
dump_stack+0x18f/0x20d lib/dump_stack.c:118
print_address_description.constprop.0.cold+0xae/0x436 mm/kasan/report.c:383
__kasan_report mm/kasan/report.c:513 [inline]
kasan_report.cold+0x1f/0x37 mm/kasan/report.c:530
dev_put include/linux/netdevice.h:3853 [inline]
netdevice_event_work_handler+0x15b/0x1b0 drivers/infiniband/core/roce_gid_mgmt.c:627
process_one_work+0x94c/0x1670 kernel/workqueue.c:2269
worker_thread+0x64c/0x1120 kernel/workqueue.c:2415
kthread+0x3b5/0x4a0 kernel/kthread.c:291
ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:293
Allocated by task 13061:
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_node include/linux/slab.h:578 [inline]
kvmalloc_node+0x61/0xf0 mm/util.c:574
kvmalloc include/linux/mm.h:753 [inline]
kvzalloc include/linux/mm.h:761 [inline]
alloc_netdev_mqs+0x97/0xdc0 net/core/dev.c:9938
__ip_tunnel_create+0x201/0x580 net/ipv4/ip_tunnel.c:254
ip_tunnel_init_net+0x32b/0x980 net/ipv4/ip_tunnel.c:1072
ops_init+0xaf/0x470 net/core/net_namespace.c:151
setup_net+0x2d8/0x850 net/core/net_namespace.c:341
copy_net_ns+0x2cf/0x5e0 net/core/net_namespace.c:482
create_new_namespaces+0x3f6/0xb10 kernel/nsproxy.c:110
unshare_nsproxy_namespaces+0xbd/0x1f0 kernel/nsproxy.c:231
ksys_unshare+0x36c/0x9a0 kernel/fork.c:2983
__do_sys_unshare kernel/fork.c:3051 [inline]
__se_sys_unshare kernel/fork.c:3049 [inline]
__x64_sys_unshare+0x2d/0x40 kernel/fork.c:3049
do_syscall_64+0x60/0xe0 arch/x86/entry/common.c:384
entry_SYSCALL_64_after_hwframe+0x44/0xa9
Freed by task 13061:
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+0xf5/0x140 mm/kasan/common.c:455
__cache_free mm/slab.c:3426 [inline]
kfree+0x103/0x2c0 mm/slab.c:3757
kvfree+0x42/0x50 mm/util.c:603
device_release+0x71/0x200 drivers/base/core.c:1559
kobject_cleanup lib/kobject.c:693 [inline]
kobject_release lib/kobject.c:722 [inline]
kref_put include/linux/kref.h:65 [inline]
kobject_put+0x1c0/0x270 lib/kobject.c:739
put_device+0x1b/0x30 drivers/base/core.c:2779
free_netdev+0x35d/0x480 net/core/dev.c:10054
__ip_tunnel_create+0x48f/0x580 net/ipv4/ip_tunnel.c:274
ip_tunnel_init_net+0x32b/0x980 net/ipv4/ip_tunnel.c:1072
ops_init+0xaf/0x470 net/core/net_namespace.c:151
setup_net+0x2d8/0x850 net/core/net_namespace.c:341
copy_net_ns+0x2cf/0x5e0 net/core/net_namespace.c:482
create_new_namespaces+0x3f6/0xb10 kernel/nsproxy.c:110
unshare_nsproxy_namespaces+0xbd/0x1f0 kernel/nsproxy.c:231
ksys_unshare+0x36c/0x9a0 kernel/fork.c:2983
__do_sys_unshare kernel/fork.c:3051 [inline]
__se_sys_unshare kernel/fork.c:3049 [inline]
__x64_sys_unshare+0x2d/0x40 kernel/fork.c:3049
do_syscall_64+0x60/0xe0 arch/x86/entry/common.c:384
entry_SYSCALL_64_after_hwframe+0x44/0xa9
The buggy address belongs to the object at ffff88807b13e000
which belongs to the cache kmalloc-4k of size 4096
The buggy address is located 1384 bytes inside of
4096-byte region [ffff88807b13e000, ffff88807b13f000)
The buggy address belongs to the page:
page:ffffea0001ec4f80 refcount:1 mapcount:0 mapping:0000000000000000 index:0x0 head:ffffea0001ec4f80 order:1 compound_mapcount:0
flags: 0xfffe0000010200(slab|head)
raw: 00fffe0000010200 ffffea0001ecce88 ffffea0001987988 ffff8880aa002000
raw: 0000000000000000 ffff88807b13e000 0000000100000001 0000000000000000
page dumped because: kasan: bad access detected
Memory state around the buggy address:
ffff88807b13e400: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
ffff88807b13e480: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
>ffff88807b13e500: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
^
ffff88807b13e580: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
ffff88807b13e600: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
==================================================================
---
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
syzbot has bisected this issue to:
commit d70c47c8dc6902db19555b7ff7e6eeb264d4ac06
Author: Heiner Kallweit <[email protected]>
Date: Thu Apr 23 19:34:33 2020 +0000
net: phy: make phy_suspend a no-op if PHY is suspended already
bisection log: https://syzkaller.appspot.com/x/bisect.txt?x=16b2aad8900000
start commit: 0bddd227 Documentation: update for gcc 4.9 requirement
git tree: upstream
final oops: https://syzkaller.appspot.com/x/report.txt?x=15b2aad8900000
console output: https://syzkaller.appspot.com/x/log.txt?x=11b2aad8900000
kernel config: https://syzkaller.appspot.com/x/.config?x=66ad203c2bb6d8b
dashboard link: https://syzkaller.appspot.com/bug?extid=20b90969babe05609947
syz repro: https://syzkaller.appspot.com/x/repro.syz?x=12a8edff100000
C reproducer: https://syzkaller.appspot.com/x/repro.c?x=167d3bb7100000
Reported-by: [email protected]
Fixes: d70c47c8dc69 ("net: phy: make phy_suspend a no-op if PHY is suspended already")
For information about bisection process see: https://goo.gl/tpsmEJ#bisection
On Thu, Jul 09, 2020 at 04:54:19PM -0700, syzbot wrote:
> Hello,
>
> syzbot found the following crash on:
>
> HEAD commit: 0bddd227 Documentation: update for gcc 4.9 requirement
> git tree: upstream
> console output: https://syzkaller.appspot.com/x/log.txt?x=1418afb7100000
> kernel config: https://syzkaller.appspot.com/x/.config?x=66ad203c2bb6d8b
> dashboard link: https://syzkaller.appspot.com/bug?extid=20b90969babe05609947
> compiler: gcc (GCC) 10.1.0-syz 20200507
> syz repro: https://syzkaller.appspot.com/x/repro.syz?x=12a8edff100000
> C reproducer: https://syzkaller.appspot.com/x/repro.c?x=167d3bb7100000
>
> IMPORTANT: if you fix the bug, please add the following tag to the commit:
> Reported-by: [email protected]
>
> ==================================================================
> BUG: KASAN: use-after-free in dev_put include/linux/netdevice.h:3853 [inline]
> BUG: KASAN: use-after-free in netdevice_event_work_handler+0x15b/0x1b0 drivers/infiniband/core/roce_gid_mgmt.c:627
> Read of size 8 at addr ffff88807b13e568 by task kworker/u4:0/7
>
> CPU: 0 PID: 7 Comm: kworker/u4:0 Not tainted 5.8.0-rc4-syzkaller #0
> Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
> Workqueue: gid-cache-wq netdevice_event_work_handler
> Call Trace:
> __dump_stack lib/dump_stack.c:77 [inline]
> dump_stack+0x18f/0x20d lib/dump_stack.c:118
> print_address_description.constprop.0.cold+0xae/0x436 mm/kasan/report.c:383
> __kasan_report mm/kasan/report.c:513 [inline]
> kasan_report.cold+0x1f/0x37 mm/kasan/report.c:530
> dev_put include/linux/netdevice.h:3853 [inline]
> netdevice_event_work_handler+0x15b/0x1b0 drivers/infiniband/core/roce_gid_mgmt.c:627
> process_one_work+0x94c/0x1670 kernel/workqueue.c:2269
> worker_thread+0x64c/0x1120 kernel/workqueue.c:2415
> kthread+0x3b5/0x4a0 kernel/kthread.c:291
> ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:293
>
> Allocated by task 13061:
> 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_node include/linux/slab.h:578 [inline]
> kvmalloc_node+0x61/0xf0 mm/util.c:574
> kvmalloc include/linux/mm.h:753 [inline]
> kvzalloc include/linux/mm.h:761 [inline]
> alloc_netdev_mqs+0x97/0xdc0 net/core/dev.c:9938
> __ip_tunnel_create+0x201/0x580 net/ipv4/ip_tunnel.c:254
> ip_tunnel_init_net+0x32b/0x980 net/ipv4/ip_tunnel.c:1072
> ops_init+0xaf/0x470 net/core/net_namespace.c:151
> setup_net+0x2d8/0x850 net/core/net_namespace.c:341
> copy_net_ns+0x2cf/0x5e0 net/core/net_namespace.c:482
> create_new_namespaces+0x3f6/0xb10 kernel/nsproxy.c:110
> unshare_nsproxy_namespaces+0xbd/0x1f0 kernel/nsproxy.c:231
> ksys_unshare+0x36c/0x9a0 kernel/fork.c:2983
> __do_sys_unshare kernel/fork.c:3051 [inline]
> __se_sys_unshare kernel/fork.c:3049 [inline]
> __x64_sys_unshare+0x2d/0x40 kernel/fork.c:3049
> do_syscall_64+0x60/0xe0 arch/x86/entry/common.c:384
> entry_SYSCALL_64_after_hwframe+0x44/0xa9
>
> Freed by task 13061:
> 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+0xf5/0x140 mm/kasan/common.c:455
> __cache_free mm/slab.c:3426 [inline]
> kfree+0x103/0x2c0 mm/slab.c:3757
> kvfree+0x42/0x50 mm/util.c:603
> device_release+0x71/0x200 drivers/base/core.c:1559
> kobject_cleanup lib/kobject.c:693 [inline]
> kobject_release lib/kobject.c:722 [inline]
> kref_put include/linux/kref.h:65 [inline]
> kobject_put+0x1c0/0x270 lib/kobject.c:739
> put_device+0x1b/0x30 drivers/base/core.c:2779
> free_netdev+0x35d/0x480 net/core/dev.c:10054
> __ip_tunnel_create+0x48f/0x580 net/ipv4/ip_tunnel.c:274
> ip_tunnel_init_net+0x32b/0x980 net/ipv4/ip_tunnel.c:1072
> ops_init+0xaf/0x470 net/core/net_namespace.c:151
> setup_net+0x2d8/0x850 net/core/net_namespace.c:341
> copy_net_ns+0x2cf/0x5e0 net/core/net_namespace.c:482
> create_new_namespaces+0x3f6/0xb10 kernel/nsproxy.c:110
> unshare_nsproxy_namespaces+0xbd/0x1f0 kernel/nsproxy.c:231
> ksys_unshare+0x36c/0x9a0 kernel/fork.c:2983
> __do_sys_unshare kernel/fork.c:3051 [inline]
> __se_sys_unshare kernel/fork.c:3049 [inline]
> __x64_sys_unshare+0x2d/0x40 kernel/fork.c:3049
> do_syscall_64+0x60/0xe0 arch/x86/entry/common.c:384
> entry_SYSCALL_64_after_hwframe+0x44/0xa9
>
> The buggy address belongs to the object at ffff88807b13e000
> which belongs to the cache kmalloc-4k of size 4096
> The buggy address is located 1384 bytes inside of
> 4096-byte region [ffff88807b13e000, ffff88807b13f000)
> The buggy address belongs to the page:
> page:ffffea0001ec4f80 refcount:1 mapcount:0 mapping:0000000000000000 index:0x0 head:ffffea0001ec4f80 order:1 compound_mapcount:0
> flags: 0xfffe0000010200(slab|head)
> raw: 00fffe0000010200 ffffea0001ecce88 ffffea0001987988 ffff8880aa002000
> raw: 0000000000000000 ffff88807b13e000 0000000100000001 0000000000000000
> page dumped because: kasan: bad access detected
>
> Memory state around the buggy address:
> ffff88807b13e400: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
> ffff88807b13e480: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
> >ffff88807b13e500: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
> ^
> ffff88807b13e580: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
> ffff88807b13e600: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
> ==================================================================
>
>
> ---
> 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
IB roce driver receives NETDEV_UNREGISTER event, calls dev_hold() and
schedules work item to execute, and before wq gets a chance to complete
it, we return to ip_tunnel.c:274 and call free_netdev(), and then later
we get UAF when scheduled function references already freed net_device
i added verbose logging to ip_tunnel.c to see pcpu_refcnt:
+ pr_info("about to free_netdev(dev) dev->pcpu_refcnt %d", netdev_refcnt_read(dev));
and got the following:
[ 410.220127][ T2944] ip_tunnel: about to free_netdev(dev) dev->pcpu_refcnt 8
i tried to make IB roce driver flush wq and work item, but i ran into
lockdep issues
also tried to modify dev core and call netdev_wait_allrefs() but ran
into rntl deadlocks
any hints or help in fixing this would be appreciated, thank you!
On Fri, Jul 31, 2020 at 09:11:22PM +0000, Rustam Kovhaev wrote:
>On Thu, Jul 09, 2020 at 04:54:19PM -0700, syzbot wrote:
>> Hello,
>>
>> syzbot found the following crash on:
>>
>> HEAD commit: 0bddd227 Documentation: update for gcc 4.9 requirement
>> git tree: upstream
>> console output: https://syzkaller.appspot.com/x/log.txt?x=1418afb7100000
>> kernel config: https://syzkaller.appspot.com/x/.config?x=66ad203c2bb6d8b
>> dashboard link: https://syzkaller.appspot.com/bug?extid=20b90969babe05609947
>> compiler: gcc (GCC) 10.1.0-syz 20200507
>> syz repro: https://syzkaller.appspot.com/x/repro.syz?x=12a8edff100000
>> C reproducer: https://syzkaller.appspot.com/x/repro.c?x=167d3bb7100000
>>
>> IMPORTANT: if you fix the bug, please add the following tag to the commit:
>> Reported-by: [email protected]
>>
>> ==================================================================
>> BUG: KASAN: use-after-free in dev_put include/linux/netdevice.h:3853 [inline]
>> BUG: KASAN: use-after-free in netdevice_event_work_handler+0x15b/0x1b0 drivers/infiniband/core/roce_gid_mgmt.c:627
>> Read of size 8 at addr ffff88807b13e568 by task kworker/u4:0/7
>>
>> CPU: 0 PID: 7 Comm: kworker/u4:0 Not tainted 5.8.0-rc4-syzkaller #0
>> Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
>> Workqueue: gid-cache-wq netdevice_event_work_handler
>> Call Trace:
>> __dump_stack lib/dump_stack.c:77 [inline]
>> dump_stack+0x18f/0x20d lib/dump_stack.c:118
>> print_address_description.constprop.0.cold+0xae/0x436 mm/kasan/report.c:383
>> __kasan_report mm/kasan/report.c:513 [inline]
>> kasan_report.cold+0x1f/0x37 mm/kasan/report.c:530
>> dev_put include/linux/netdevice.h:3853 [inline]
>> netdevice_event_work_handler+0x15b/0x1b0 drivers/infiniband/core/roce_gid_mgmt.c:627
>> process_one_work+0x94c/0x1670 kernel/workqueue.c:2269
>> worker_thread+0x64c/0x1120 kernel/workqueue.c:2415
>> kthread+0x3b5/0x4a0 kernel/kthread.c:291
>> ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:293
>>
>> Allocated by task 13061:
>> 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_node include/linux/slab.h:578 [inline]
>> kvmalloc_node+0x61/0xf0 mm/util.c:574
>> kvmalloc include/linux/mm.h:753 [inline]
>> kvzalloc include/linux/mm.h:761 [inline]
>> alloc_netdev_mqs+0x97/0xdc0 net/core/dev.c:9938
>> __ip_tunnel_create+0x201/0x580 net/ipv4/ip_tunnel.c:254
>> ip_tunnel_init_net+0x32b/0x980 net/ipv4/ip_tunnel.c:1072
>> ops_init+0xaf/0x470 net/core/net_namespace.c:151
>> setup_net+0x2d8/0x850 net/core/net_namespace.c:341
>> copy_net_ns+0x2cf/0x5e0 net/core/net_namespace.c:482
>> create_new_namespaces+0x3f6/0xb10 kernel/nsproxy.c:110
>> unshare_nsproxy_namespaces+0xbd/0x1f0 kernel/nsproxy.c:231
>> ksys_unshare+0x36c/0x9a0 kernel/fork.c:2983
>> __do_sys_unshare kernel/fork.c:3051 [inline]
>> __se_sys_unshare kernel/fork.c:3049 [inline]
>> __x64_sys_unshare+0x2d/0x40 kernel/fork.c:3049
>> do_syscall_64+0x60/0xe0 arch/x86/entry/common.c:384
>> entry_SYSCALL_64_after_hwframe+0x44/0xa9
>>
>> Freed by task 13061:
>> 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+0xf5/0x140 mm/kasan/common.c:455
>> __cache_free mm/slab.c:3426 [inline]
>> kfree+0x103/0x2c0 mm/slab.c:3757
>> kvfree+0x42/0x50 mm/util.c:603
>> device_release+0x71/0x200 drivers/base/core.c:1559
>> kobject_cleanup lib/kobject.c:693 [inline]
>> kobject_release lib/kobject.c:722 [inline]
>> kref_put include/linux/kref.h:65 [inline]
>> kobject_put+0x1c0/0x270 lib/kobject.c:739
>> put_device+0x1b/0x30 drivers/base/core.c:2779
>> free_netdev+0x35d/0x480 net/core/dev.c:10054
>> __ip_tunnel_create+0x48f/0x580 net/ipv4/ip_tunnel.c:274
>> ip_tunnel_init_net+0x32b/0x980 net/ipv4/ip_tunnel.c:1072
>> ops_init+0xaf/0x470 net/core/net_namespace.c:151
>> setup_net+0x2d8/0x850 net/core/net_namespace.c:341
>> copy_net_ns+0x2cf/0x5e0 net/core/net_namespace.c:482
>> create_new_namespaces+0x3f6/0xb10 kernel/nsproxy.c:110
>> unshare_nsproxy_namespaces+0xbd/0x1f0 kernel/nsproxy.c:231
>> ksys_unshare+0x36c/0x9a0 kernel/fork.c:2983
>> __do_sys_unshare kernel/fork.c:3051 [inline]
>> __se_sys_unshare kernel/fork.c:3049 [inline]
>> __x64_sys_unshare+0x2d/0x40 kernel/fork.c:3049
>> do_syscall_64+0x60/0xe0 arch/x86/entry/common.c:384
>> entry_SYSCALL_64_after_hwframe+0x44/0xa9
>>
>> The buggy address belongs to the object at ffff88807b13e000
>> which belongs to the cache kmalloc-4k of size 4096
>> The buggy address is located 1384 bytes inside of
>> 4096-byte region [ffff88807b13e000, ffff88807b13f000)
>> The buggy address belongs to the page:
>> page:ffffea0001ec4f80 refcount:1 mapcount:0 mapping:0000000000000000 index:0x0 head:ffffea0001ec4f80 order:1 compound_mapcount:0
>> flags: 0xfffe0000010200(slab|head)
>> raw: 00fffe0000010200 ffffea0001ecce88 ffffea0001987988 ffff8880aa002000
>> raw: 0000000000000000 ffff88807b13e000 0000000100000001 0000000000000000
>> page dumped because: kasan: bad access detected
>>
>> Memory state around the buggy address:
>> ffff88807b13e400: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
>> ffff88807b13e480: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
>> >ffff88807b13e500: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
>> ^
>> ffff88807b13e580: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
>> ffff88807b13e600: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
>> ==================================================================
>>
>>
>> ---
>> 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
>
>IB roce driver receives NETDEV_UNREGISTER event, calls dev_hold() and
>schedules work item to execute, and before wq gets a chance to complete
>it, we return to ip_tunnel.c:274 and call free_netdev(), and then later
>we get UAF when scheduled function references already freed net_device
>
>i added verbose logging to ip_tunnel.c to see pcpu_refcnt:
>+ pr_info("about to free_netdev(dev) dev->pcpu_refcnt %d", netdev_refcnt_read(dev));
>
>and got the following:
>[ 410.220127][ T2944] ip_tunnel: about to free_netdev(dev) dev->pcpu_refcnt 8
>
>i tried to make IB roce driver flush wq and work item, but i ran into
>lockdep issues
>also tried to modify dev core and call netdev_wait_allrefs() but ran
>into rntl deadlocks
>
>any hints or help in fixing this would be appreciated, thank you!
Congratulations on your latest patch [1] which has fixed this issue! I've
also been trying to fix this bug. Your solution is the right one and simpler
than mine:) I've also realized struct device shouldn't be freed at all
since dev_hold is called but haven't figured out why,
// drivers/infiniband/core/roce_gid_mgmt.c
static int netdevice_queue_work(struct netdev_event_work_cmd *cmds,
struct net_device *ndev)
{
...
for (i = 0; i < ARRAY_SIZE(ndev_work->cmds) && ndev_work->cmds[i].cb; i++) {
dev_hold(ndev_work->cmds[i].ndev);
...
}
...
return NOTIFY_DONE;
}
But maybe we could make an improvement which is to fix what makes the
nofitied callback functions mpls_dev_notify and addrconf_notify fail in
the first place. Currently I simply let mpls_dev_notify and addrconf_notify
return NOTIFY_DONE [2] [3] so call_netdevice_notifiers and register_netdevice
would succeed.
My observation is that mpls_dev_notify and addrconf_notify are not per-netns
netdevice callback functions of the notified (the subscriber) and they could
fail.
When per-netns netdevice callback functions are successful and global ones
like mpls_dev_notify fail, register_netdevice would then fails.
// net/core/dev.c
static int call_netdevice_notifiers_info(unsigned long val,
struct netdev_notifier_info *info)
{
struct net *net = dev_net(info->dev);
int ret;
ASSERT_RTNL();
/* Run per-netns notifier block chain first, then run the global one.
* Hopefully, one day, the global one is going to be removed after
* all notifier block registrators get converted to be per-netns.
*/
ret = raw_notifier_call_chain(&net->netdev_chain, val, info);
if (ret & NOTIFY_STOP_MASK)
return ret;
return raw_notifier_call_chain(&netdev_chain, val, info);
}
This causes the created net_device struct to be destroyed. Since per-netns
netdevice callback functions have been successful, the netdevice is still
used by netdevice_event_work_handler which cause this "KASAN: use-after-free"
bug.
[1] https://syzkaller.appspot.com/text?tag=Patch&x=1799f8a2900000
[2] https://github.com/coiby/linux/commit/859f817317c8cd4a17af8879094db8697a2c7754
[3] https://github.com/coiby/linux/commit/260ddb9ec9b124ca7ad93f368eadb90b16edf2ef
On Fri, Jul 31, 2020 at 02:11:22PM -0700, Rustam Kovhaev wrote:
> On Thu, Jul 09, 2020 at 04:54:19PM -0700, syzbot wrote:
> > Hello,
> >
> > syzbot found the following crash on:
> >
> > HEAD commit: 0bddd227 Documentation: update for gcc 4.9 requirement
> > git tree: upstream
> > console output: https://syzkaller.appspot.com/x/log.txt?x=1418afb7100000
> > kernel config: https://syzkaller.appspot.com/x/.config?x=66ad203c2bb6d8b
> > dashboard link: https://syzkaller.appspot.com/bug?extid=20b90969babe05609947
> > compiler: gcc (GCC) 10.1.0-syz 20200507
> > syz repro: https://syzkaller.appspot.com/x/repro.syz?x=12a8edff100000
> > C reproducer: https://syzkaller.appspot.com/x/repro.c?x=167d3bb7100000
> >
> > IMPORTANT: if you fix the bug, please add the following tag to the commit:
> > Reported-by: [email protected]
> >
> > ==================================================================
> > BUG: KASAN: use-after-free in dev_put include/linux/netdevice.h:3853 [inline]
> > BUG: KASAN: use-after-free in netdevice_event_work_handler+0x15b/0x1b0 drivers/infiniband/core/roce_gid_mgmt.c:627
> > Read of size 8 at addr ffff88807b13e568 by task kworker/u4:0/7
> >
> > CPU: 0 PID: 7 Comm: kworker/u4:0 Not tainted 5.8.0-rc4-syzkaller #0
> > Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
> > Workqueue: gid-cache-wq netdevice_event_work_handler
> > Call Trace:
> > __dump_stack lib/dump_stack.c:77 [inline]
> > dump_stack+0x18f/0x20d lib/dump_stack.c:118
> > print_address_description.constprop.0.cold+0xae/0x436 mm/kasan/report.c:383
> > __kasan_report mm/kasan/report.c:513 [inline]
> > kasan_report.cold+0x1f/0x37 mm/kasan/report.c:530
> > dev_put include/linux/netdevice.h:3853 [inline]
> > netdevice_event_work_handler+0x15b/0x1b0 drivers/infiniband/core/roce_gid_mgmt.c:627
> > process_one_work+0x94c/0x1670 kernel/workqueue.c:2269
> > worker_thread+0x64c/0x1120 kernel/workqueue.c:2415
> > kthread+0x3b5/0x4a0 kernel/kthread.c:291
> > ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:293
> >
> > Allocated by task 13061:
> > 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_node include/linux/slab.h:578 [inline]
> > kvmalloc_node+0x61/0xf0 mm/util.c:574
> > kvmalloc include/linux/mm.h:753 [inline]
> > kvzalloc include/linux/mm.h:761 [inline]
> > alloc_netdev_mqs+0x97/0xdc0 net/core/dev.c:9938
> > __ip_tunnel_create+0x201/0x580 net/ipv4/ip_tunnel.c:254
> > ip_tunnel_init_net+0x32b/0x980 net/ipv4/ip_tunnel.c:1072
> > ops_init+0xaf/0x470 net/core/net_namespace.c:151
> > setup_net+0x2d8/0x850 net/core/net_namespace.c:341
> > copy_net_ns+0x2cf/0x5e0 net/core/net_namespace.c:482
> > create_new_namespaces+0x3f6/0xb10 kernel/nsproxy.c:110
> > unshare_nsproxy_namespaces+0xbd/0x1f0 kernel/nsproxy.c:231
> > ksys_unshare+0x36c/0x9a0 kernel/fork.c:2983
> > __do_sys_unshare kernel/fork.c:3051 [inline]
> > __se_sys_unshare kernel/fork.c:3049 [inline]
> > __x64_sys_unshare+0x2d/0x40 kernel/fork.c:3049
> > do_syscall_64+0x60/0xe0 arch/x86/entry/common.c:384
> > entry_SYSCALL_64_after_hwframe+0x44/0xa9
> >
> > Freed by task 13061:
> > 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+0xf5/0x140 mm/kasan/common.c:455
> > __cache_free mm/slab.c:3426 [inline]
> > kfree+0x103/0x2c0 mm/slab.c:3757
> > kvfree+0x42/0x50 mm/util.c:603
> > device_release+0x71/0x200 drivers/base/core.c:1559
> > kobject_cleanup lib/kobject.c:693 [inline]
> > kobject_release lib/kobject.c:722 [inline]
> > kref_put include/linux/kref.h:65 [inline]
> > kobject_put+0x1c0/0x270 lib/kobject.c:739
> > put_device+0x1b/0x30 drivers/base/core.c:2779
> > free_netdev+0x35d/0x480 net/core/dev.c:10054
> > __ip_tunnel_create+0x48f/0x580 net/ipv4/ip_tunnel.c:274
> > ip_tunnel_init_net+0x32b/0x980 net/ipv4/ip_tunnel.c:1072
> > ops_init+0xaf/0x470 net/core/net_namespace.c:151
> > setup_net+0x2d8/0x850 net/core/net_namespace.c:341
> > copy_net_ns+0x2cf/0x5e0 net/core/net_namespace.c:482
> > create_new_namespaces+0x3f6/0xb10 kernel/nsproxy.c:110
> > unshare_nsproxy_namespaces+0xbd/0x1f0 kernel/nsproxy.c:231
> > ksys_unshare+0x36c/0x9a0 kernel/fork.c:2983
> > __do_sys_unshare kernel/fork.c:3051 [inline]
> > __se_sys_unshare kernel/fork.c:3049 [inline]
> > __x64_sys_unshare+0x2d/0x40 kernel/fork.c:3049
> > do_syscall_64+0x60/0xe0 arch/x86/entry/common.c:384
> > entry_SYSCALL_64_after_hwframe+0x44/0xa9
> >
> > The buggy address belongs to the object at ffff88807b13e000
> > which belongs to the cache kmalloc-4k of size 4096
> > The buggy address is located 1384 bytes inside of
> > 4096-byte region [ffff88807b13e000, ffff88807b13f000)
> > The buggy address belongs to the page:
> > page:ffffea0001ec4f80 refcount:1 mapcount:0 mapping:0000000000000000 index:0x0 head:ffffea0001ec4f80 order:1 compound_mapcount:0
> > flags: 0xfffe0000010200(slab|head)
> > raw: 00fffe0000010200 ffffea0001ecce88 ffffea0001987988 ffff8880aa002000
> > raw: 0000000000000000 ffff88807b13e000 0000000100000001 0000000000000000
> > page dumped because: kasan: bad access detected
> >
> > Memory state around the buggy address:
> > ffff88807b13e400: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
> > ffff88807b13e480: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
> > >ffff88807b13e500: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
> > ^
> > ffff88807b13e580: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
> > ffff88807b13e600: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
> > ==================================================================
> >
> >
> > ---
> > 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
>
> IB roce driver receives NETDEV_UNREGISTER event, calls dev_hold() and
> schedules work item to execute, and before wq gets a chance to complete
> it, we return to ip_tunnel.c:274 and call free_netdev(), and then later
> we get UAF when scheduled function references already freed net_device
>
> i added verbose logging to ip_tunnel.c to see pcpu_refcnt:
> + pr_info("about to free_netdev(dev) dev->pcpu_refcnt %d", netdev_refcnt_read(dev));
>
> and got the following:
> [ 410.220127][ T2944] ip_tunnel: about to free_netdev(dev) dev->pcpu_refcnt 8
>
> i tried to make IB roce driver flush wq and work item, but i ran into
> lockdep issues
> also tried to modify dev core and call netdev_wait_allrefs() but ran
> into rntl deadlocks
>
> any hints or help in fixing this would be appreciated, thank you!
>
does the patch below look sane to you? or is it complete nonsense?
syzbot test came out OK, but it might not mean anything
diff --git a/drivers/infiniband/core/roce_gid_mgmt.c b/drivers/infiniband/core/roce_gid_mgmt.c
index 2860def84f4d..b31c8969c8b2 100644
--- a/drivers/infiniband/core/roce_gid_mgmt.c
+++ b/drivers/infiniband/core/roce_gid_mgmt.c
@@ -626,6 +626,7 @@ static void netdevice_event_work_handler(struct work_struct *_work)
work->cmds[i].ndev);
dev_put(work->cmds[i].ndev);
dev_put(work->cmds[i].filter_ndev);
+ put_device(&work->cmds[i].ndev->dev);
}
kfree(work);
@@ -649,6 +650,7 @@ static int netdevice_queue_work(struct netdev_event_work_cmd *cmds,
ndev_work->cmds[i].filter_ndev = ndev;
dev_hold(ndev_work->cmds[i].ndev);
dev_hold(ndev_work->cmds[i].filter_ndev);
+ get_device(&ndev_work->cmds[i].ndev->dev);
}
INIT_WORK(&ndev_work->work, netdevice_event_work_handler);
On Fri, Jul 31, 2020 at 02:11:22PM -0700, Rustam Kovhaev wrote:
> IB roce driver receives NETDEV_UNREGISTER event, calls dev_hold() and
> schedules work item to execute, and before wq gets a chance to complete
> it, we return to ip_tunnel.c:274 and call free_netdev(), and then later
> we get UAF when scheduled function references already freed net_device
>
> i added verbose logging to ip_tunnel.c to see pcpu_refcnt:
> + pr_info("about to free_netdev(dev) dev->pcpu_refcnt %d", netdev_refcnt_read(dev));
>
> and got the following:
> [ 410.220127][ T2944] ip_tunnel: about to free_netdev(dev) dev->pcpu_refcnt 8
I think there is a missing call to netdev_wait_allrefs() in the
rollback_registered_many().
The normal success flow has this wait after delivering
NETDEV_UNREGISTER, the error unwind for register_netdevice should as
well.
If the netdevice can progress to free while a dev_hold is active I
think it means dev_hold is functionally useless.
Jason
On Sun, Aug 02, 2020 at 07:22:26PM -0300, Jason Gunthorpe wrote:
> On Fri, Jul 31, 2020 at 02:11:22PM -0700, Rustam Kovhaev wrote:
>
> > IB roce driver receives NETDEV_UNREGISTER event, calls dev_hold() and
> > schedules work item to execute, and before wq gets a chance to complete
> > it, we return to ip_tunnel.c:274 and call free_netdev(), and then later
> > we get UAF when scheduled function references already freed net_device
> >
> > i added verbose logging to ip_tunnel.c to see pcpu_refcnt:
> > + pr_info("about to free_netdev(dev) dev->pcpu_refcnt %d", netdev_refcnt_read(dev));
> >
> > and got the following:
> > [ 410.220127][ T2944] ip_tunnel: about to free_netdev(dev) dev->pcpu_refcnt 8
>
> I think there is a missing call to netdev_wait_allrefs() in the
> rollback_registered_many().
calling it there leads to rtnl deadlock, i think we should call
net_set_todo(), so that later when we call rtnl_unlock() it will
execute netdev_run_todo() and there it will proceed to calling
netdev_wait_allrefs(), but in ip tunnel i will need get
free_netdev() to be called after we unlock rtnl mutex
i'll try to send a new patch for review
> The normal success flow has this wait after delivering
> NETDEV_UNREGISTER, the error unwind for register_netdevice should as
> well.
>
> If the netdevice can progress to free while a dev_hold is active I
> think it means dev_hold is functionally useless.
good point
On Tue, Aug 04, 2020 at 01:00:13PM -0700, Rustam Kovhaev wrote:
> On Sun, Aug 02, 2020 at 07:22:26PM -0300, Jason Gunthorpe wrote:
> > On Fri, Jul 31, 2020 at 02:11:22PM -0700, Rustam Kovhaev wrote:
> >
> > > IB roce driver receives NETDEV_UNREGISTER event, calls dev_hold() and
> > > schedules work item to execute, and before wq gets a chance to complete
> > > it, we return to ip_tunnel.c:274 and call free_netdev(), and then later
> > > we get UAF when scheduled function references already freed net_device
> > >
> > > i added verbose logging to ip_tunnel.c to see pcpu_refcnt:
> > > + pr_info("about to free_netdev(dev) dev->pcpu_refcnt %d", netdev_refcnt_read(dev));
> > >
> > > and got the following:
> > > [ 410.220127][ T2944] ip_tunnel: about to free_netdev(dev) dev->pcpu_refcnt 8
> >
> > I think there is a missing call to netdev_wait_allrefs() in the
> > rollback_registered_many().
> calling it there leads to rtnl deadlock, i think we should call
> net_set_todo(), so that later when we call rtnl_unlock() it will
> execute netdev_run_todo() and there it will proceed to calling
> netdev_wait_allrefs(), but in ip tunnel i will need get
> free_netdev() to be called after we unlock rtnl mutex
> i'll try to send a new patch for review
Oh the whole register is called under rtnl? Yikes..
This is probably a systemic problem with register_netdevice error
unwind, not just ip tunnel
The other way to handle it would be to organize things so that
register cannot fail once it starts calling notifiers?
Jason