Re: KASAN: use-after-free Read in work_is_static

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* Re: KASAN: use-after-free Read in work_is_static_object
       [not found] <001a1144d6e8ef29870562424c44@google.com>
@ 2018-01-08 11:55 ` Dmitry Vyukov
  2018-01-08 11:58   ` Dmitry Vyukov
  0 siblings, 1 reply; 3+ messages in thread
From: Dmitry Vyukov @ 2018-01-08 11:55 UTC (permalink / raw)
  To: syzbot, David Miller, Cong Wang, Tom Herbert, Al Viro,
	Eric Dumazet, Eric Biggers, netdev
  Cc: Lai Jiangshan, LKML, syzkaller-bugs, Tejun Heo

On Mon, Jan 8, 2018 at 12:43 PM, syzbot
<syzbot+40396d275b34b0dd5dad@syzkaller.appspotmail.com> wrote:
> Hello,
>
> syzkaller hit the following crash on
> f66faae2f80a45feafc04ce63ef744ac4b6e8c05
> git://git.kernel.org/pub/scm/linux/kernel/git/davem/net-next.git/master
> compiler: gcc (GCC) 7.1.1 20170620
> .config is attached
> Raw console output is attached.
> Unfortunately, I don't have any reproducer for this bug yet.
>
>
> IMPORTANT: if you fix the bug, please add the following tag to the commit:
> Reported-by: syzbot+40396d275b34b0dd5dad@syzkaller.appspotmail.com
> It will help syzbot understand when the bug is fixed. See footer for
> details.
> If you forward the report, please keep this part and the footer.


This looks like an issue in kcm sockets, so +kcm maintainers.


> device ip6_vti0 entered promiscuous mode
> ==================================================================
> BUG: KASAN: use-after-free in constant_test_bit
> arch/x86/include/asm/bitops.h:325 [inline]
> BUG: KASAN: use-after-free in work_is_static_object+0x39/0x40
> kernel/workqueue.c:443
> Read of size 8 at addr ffff8801beca5788 by task syz-executor2/12922
>
> CPU: 0 PID: 12922 Comm: syz-executor2 Not tainted 4.15.0-rc5+ #178
> Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS
> Google 01/01/2011
> Call Trace:
>  __dump_stack lib/dump_stack.c:17 [inline]
>  dump_stack+0x194/0x257 lib/dump_stack.c:53
>  print_address_description+0x73/0x250 mm/kasan/report.c:252
>  kasan_report_error mm/kasan/report.c:351 [inline]
>  kasan_report+0x25b/0x340 mm/kasan/report.c:409
>  __asan_report_load8_noabort+0x14/0x20 mm/kasan/report.c:430
>  constant_test_bit arch/x86/include/asm/bitops.h:325 [inline]
>  work_is_static_object+0x39/0x40 kernel/workqueue.c:443
>  debug_object_activate+0x36f/0x730 lib/debugobjects.c:470
>  debug_work_activate kernel/workqueue.c:492 [inline]
>  __queue_work+0x163/0x1230 kernel/workqueue.c:1381
>  queue_work_on+0x16a/0x1c0 kernel/workqueue.c:1487
>  queue_work include/linux/workqueue.h:488 [inline]
>  strp_check_rcv+0x25/0x30 net/strparser/strparser.c:552
>  kcm_attach net/kcm/kcmsock.c:1439 [inline]
>  kcm_attach_ioctl net/kcm/kcmsock.c:1460 [inline]
>  kcm_ioctl+0x82f/0x1690 net/kcm/kcmsock.c:1665
>  sock_do_ioctl+0x65/0xb0 net/socket.c:956
>  sock_ioctl+0x2c2/0x440 net/socket.c:1053
>  vfs_ioctl fs/ioctl.c:46 [inline]
>  do_vfs_ioctl+0x1b1/0x1520 fs/ioctl.c:686
>  SYSC_ioctl fs/ioctl.c:701 [inline]
>  SyS_ioctl+0x8f/0xc0 fs/ioctl.c:692
>  entry_SYSCALL_64_fastpath+0x23/0x9a
> RIP: 0033:0x452ac9
> RSP: 002b:00007f1bbd860c58 EFLAGS: 00000212 ORIG_RAX: 0000000000000010
> RAX: ffffffffffffffda RBX: 000000000071bea0 RCX: 0000000000452ac9
> RDX: 0000000020954ff8 RSI: 00000000000089e0 RDI: 0000000000000017
> RBP: 000000000000057b R08: 0000000000000000 R09: 0000000000000000
> R10: 0000000000000000 R11: 0000000000000212 R12: 00000000006f6428
> R13: 00000000ffffffff R14: 00007f1bbd8616d4 R15: 0000000000000000
>
> Allocated by task 12922:
>  save_stack+0x43/0xd0 mm/kasan/kasan.c:447
>  set_track mm/kasan/kasan.c:459 [inline]
>  kasan_kmalloc+0xad/0xe0 mm/kasan/kasan.c:551
>  kasan_slab_alloc+0x12/0x20 mm/kasan/kasan.c:489
>  kmem_cache_alloc+0x12e/0x760 mm/slab.c:3544
>  kmem_cache_zalloc include/linux/slab.h:678 [inline]
>  kcm_attach net/kcm/kcmsock.c:1394 [inline]
>  kcm_attach_ioctl net/kcm/kcmsock.c:1460 [inline]
>  kcm_ioctl+0x2d2/0x1690 net/kcm/kcmsock.c:1665
>  sock_do_ioctl+0x65/0xb0 net/socket.c:956
>  sock_ioctl+0x2c2/0x440 net/socket.c:1053
>  vfs_ioctl fs/ioctl.c:46 [inline]
>  do_vfs_ioctl+0x1b1/0x1520 fs/ioctl.c:686
>  SYSC_ioctl fs/ioctl.c:701 [inline]
>  SyS_ioctl+0x8f/0xc0 fs/ioctl.c:692
>  entry_SYSCALL_64_fastpath+0x23/0x9a
>
> Freed by task 12929:
>  save_stack+0x43/0xd0 mm/kasan/kasan.c:447
>  set_track mm/kasan/kasan.c:459 [inline]
>  kasan_slab_free+0x71/0xc0 mm/kasan/kasan.c:524
>  __cache_free mm/slab.c:3488 [inline]
>  kmem_cache_free+0x83/0x2a0 mm/slab.c:3746
>  kcm_unattach+0xe53/0x1510 net/kcm/kcmsock.c:1563
>  kcm_unattach_ioctl net/kcm/kcmsock.c:1608 [inline]
>  kcm_ioctl+0xe54/0x1690 net/kcm/kcmsock.c:1675
>  sock_do_ioctl+0x65/0xb0 net/socket.c:956
>  sock_ioctl+0x2c2/0x440 net/socket.c:1053
>  vfs_ioctl fs/ioctl.c:46 [inline]
>  do_vfs_ioctl+0x1b1/0x1520 fs/ioctl.c:686
>  SYSC_ioctl fs/ioctl.c:701 [inline]
>  SyS_ioctl+0x8f/0xc0 fs/ioctl.c:692
>  entry_SYSCALL_64_fastpath+0x23/0x9a
>
> The buggy address belongs to the object at ffff8801beca56c0
>  which belongs to the cache kcm_psock_cache of size 544
> The buggy address is located 200 bytes inside of
>  544-byte region [ffff8801beca56c0, ffff8801beca58e0)
> The buggy address belongs to the page:
> page:000000005180a80a count:1 mapcount:0 mapping:0000000058aa9a5c index:0x0
> compound_mapcount: 0
> flags: 0x2fffc0000008100(slab|head)
> raw: 02fffc0000008100 ffff8801beca40c0 0000000000000000 000000010000000b
> raw: ffff8801d31e8a48 ffff8801d31e8a48 ffff8801d3f6a380 0000000000000000
> page dumped because: kasan: bad access detected
>
> Memory state around the buggy address:
>  ffff8801beca5680: fc fc fc fc fc fc fc fc fb fb fb fb fb fb fb fb
>  ffff8801beca5700: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
>>
>> ffff8801beca5780: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
>
>                       ^
>  ffff8801beca5800: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
>  ffff8801beca5880: fb fb fb fb fb fb fb fb fb fb fb fb fc fc fc fc
> ==================================================================
>
>
> ---
> This bug is generated by a dumb bot. It may contain errors.
> See https://goo.gl/tpsmEJ for details.
> Direct all questions to syzkaller@googlegroups.com.
>
> syzbot will keep track of this bug report.
> If you forgot to add the Reported-by tag, once the fix for this bug is
> merged
> into any tree, please reply to this email with:
> #syz fix: exact-commit-title
> To mark this as a duplicate of another syzbot report, please reply with:
> #syz dup: exact-subject-of-another-report
> If it's a one-off invalid bug report, please reply with:
> #syz invalid
> Note: if the crash happens again, it will cause creation of a new bug
> report.
> Note: all commands must start from beginning of the line in the email body.
>
> --
> 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
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> To view this discussion on the web visit
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> For more options, visit https://groups.google.com/d/optout.

^ permalink raw reply	[flat|nested] 3+ messages in thread

* Re: KASAN: use-after-free Read in work_is_static_object
  2018-01-08 11:55 ` KASAN: use-after-free Read in work_is_static_object Dmitry Vyukov
@ 2018-01-08 11:58   ` Dmitry Vyukov
  2018-05-09  2:49     ` Eric Biggers
  0 siblings, 1 reply; 3+ messages in thread
From: Dmitry Vyukov @ 2018-01-08 11:58 UTC (permalink / raw)
  To: syzbot, David Miller, Cong Wang, Tom Herbert, Al Viro,
	Eric Dumazet, Eric Biggers, netdev
  Cc: Lai Jiangshan, LKML, syzkaller-bugs, Tejun Heo

On Mon, Jan 8, 2018 at 12:55 PM, Dmitry Vyukov <dvyukov@google.com> wrote:
> On Mon, Jan 8, 2018 at 12:43 PM, syzbot
> <syzbot+40396d275b34b0dd5dad@syzkaller.appspotmail.com> wrote:
>> Hello,
>>
>> syzkaller hit the following crash on
>> f66faae2f80a45feafc04ce63ef744ac4b6e8c05
>> git://git.kernel.org/pub/scm/linux/kernel/git/davem/net-next.git/master
>> compiler: gcc (GCC) 7.1.1 20170620
>> .config is attached
>> Raw console output is attached.
>> Unfortunately, I don't have any reproducer for this bug yet.
>>
>>
>> IMPORTANT: if you fix the bug, please add the following tag to the commit:
>> Reported-by: syzbot+40396d275b34b0dd5dad@syzkaller.appspotmail.com
>> It will help syzbot understand when the bug is fixed. See footer for
>> details.
>> If you forward the report, please keep this part and the footer.
>
>
> This looks like an issue in kcm sockets, so +kcm maintainers.

FTR, guilty file extraction was fixed to ignore kernel/workqueue.c:
https://github.com/google/syzkaller/commit/1014e5506e35965f3bad13fabb08666134d0b273
Presumably for bugs in workqueue usually the caller is guilty.


>> device ip6_vti0 entered promiscuous mode
>> ==================================================================
>> BUG: KASAN: use-after-free in constant_test_bit
>> arch/x86/include/asm/bitops.h:325 [inline]
>> BUG: KASAN: use-after-free in work_is_static_object+0x39/0x40
>> kernel/workqueue.c:443
>> Read of size 8 at addr ffff8801beca5788 by task syz-executor2/12922
>>
>> CPU: 0 PID: 12922 Comm: syz-executor2 Not tainted 4.15.0-rc5+ #178
>> Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS
>> Google 01/01/2011
>> Call Trace:
>>  __dump_stack lib/dump_stack.c:17 [inline]
>>  dump_stack+0x194/0x257 lib/dump_stack.c:53
>>  print_address_description+0x73/0x250 mm/kasan/report.c:252
>>  kasan_report_error mm/kasan/report.c:351 [inline]
>>  kasan_report+0x25b/0x340 mm/kasan/report.c:409
>>  __asan_report_load8_noabort+0x14/0x20 mm/kasan/report.c:430
>>  constant_test_bit arch/x86/include/asm/bitops.h:325 [inline]
>>  work_is_static_object+0x39/0x40 kernel/workqueue.c:443
>>  debug_object_activate+0x36f/0x730 lib/debugobjects.c:470
>>  debug_work_activate kernel/workqueue.c:492 [inline]
>>  __queue_work+0x163/0x1230 kernel/workqueue.c:1381
>>  queue_work_on+0x16a/0x1c0 kernel/workqueue.c:1487
>>  queue_work include/linux/workqueue.h:488 [inline]
>>  strp_check_rcv+0x25/0x30 net/strparser/strparser.c:552
>>  kcm_attach net/kcm/kcmsock.c:1439 [inline]
>>  kcm_attach_ioctl net/kcm/kcmsock.c:1460 [inline]
>>  kcm_ioctl+0x82f/0x1690 net/kcm/kcmsock.c:1665
>>  sock_do_ioctl+0x65/0xb0 net/socket.c:956
>>  sock_ioctl+0x2c2/0x440 net/socket.c:1053
>>  vfs_ioctl fs/ioctl.c:46 [inline]
>>  do_vfs_ioctl+0x1b1/0x1520 fs/ioctl.c:686
>>  SYSC_ioctl fs/ioctl.c:701 [inline]
>>  SyS_ioctl+0x8f/0xc0 fs/ioctl.c:692
>>  entry_SYSCALL_64_fastpath+0x23/0x9a
>> RIP: 0033:0x452ac9
>> RSP: 002b:00007f1bbd860c58 EFLAGS: 00000212 ORIG_RAX: 0000000000000010
>> RAX: ffffffffffffffda RBX: 000000000071bea0 RCX: 0000000000452ac9
>> RDX: 0000000020954ff8 RSI: 00000000000089e0 RDI: 0000000000000017
>> RBP: 000000000000057b R08: 0000000000000000 R09: 0000000000000000
>> R10: 0000000000000000 R11: 0000000000000212 R12: 00000000006f6428
>> R13: 00000000ffffffff R14: 00007f1bbd8616d4 R15: 0000000000000000
>>
>> Allocated by task 12922:
>>  save_stack+0x43/0xd0 mm/kasan/kasan.c:447
>>  set_track mm/kasan/kasan.c:459 [inline]
>>  kasan_kmalloc+0xad/0xe0 mm/kasan/kasan.c:551
>>  kasan_slab_alloc+0x12/0x20 mm/kasan/kasan.c:489
>>  kmem_cache_alloc+0x12e/0x760 mm/slab.c:3544
>>  kmem_cache_zalloc include/linux/slab.h:678 [inline]
>>  kcm_attach net/kcm/kcmsock.c:1394 [inline]
>>  kcm_attach_ioctl net/kcm/kcmsock.c:1460 [inline]
>>  kcm_ioctl+0x2d2/0x1690 net/kcm/kcmsock.c:1665
>>  sock_do_ioctl+0x65/0xb0 net/socket.c:956
>>  sock_ioctl+0x2c2/0x440 net/socket.c:1053
>>  vfs_ioctl fs/ioctl.c:46 [inline]
>>  do_vfs_ioctl+0x1b1/0x1520 fs/ioctl.c:686
>>  SYSC_ioctl fs/ioctl.c:701 [inline]
>>  SyS_ioctl+0x8f/0xc0 fs/ioctl.c:692
>>  entry_SYSCALL_64_fastpath+0x23/0x9a
>>
>> Freed by task 12929:
>>  save_stack+0x43/0xd0 mm/kasan/kasan.c:447
>>  set_track mm/kasan/kasan.c:459 [inline]
>>  kasan_slab_free+0x71/0xc0 mm/kasan/kasan.c:524
>>  __cache_free mm/slab.c:3488 [inline]
>>  kmem_cache_free+0x83/0x2a0 mm/slab.c:3746
>>  kcm_unattach+0xe53/0x1510 net/kcm/kcmsock.c:1563
>>  kcm_unattach_ioctl net/kcm/kcmsock.c:1608 [inline]
>>  kcm_ioctl+0xe54/0x1690 net/kcm/kcmsock.c:1675
>>  sock_do_ioctl+0x65/0xb0 net/socket.c:956
>>  sock_ioctl+0x2c2/0x440 net/socket.c:1053
>>  vfs_ioctl fs/ioctl.c:46 [inline]
>>  do_vfs_ioctl+0x1b1/0x1520 fs/ioctl.c:686
>>  SYSC_ioctl fs/ioctl.c:701 [inline]
>>  SyS_ioctl+0x8f/0xc0 fs/ioctl.c:692
>>  entry_SYSCALL_64_fastpath+0x23/0x9a
>>
>> The buggy address belongs to the object at ffff8801beca56c0
>>  which belongs to the cache kcm_psock_cache of size 544
>> The buggy address is located 200 bytes inside of
>>  544-byte region [ffff8801beca56c0, ffff8801beca58e0)
>> The buggy address belongs to the page:
>> page:000000005180a80a count:1 mapcount:0 mapping:0000000058aa9a5c index:0x0
>> compound_mapcount: 0
>> flags: 0x2fffc0000008100(slab|head)
>> raw: 02fffc0000008100 ffff8801beca40c0 0000000000000000 000000010000000b
>> raw: ffff8801d31e8a48 ffff8801d31e8a48 ffff8801d3f6a380 0000000000000000
>> page dumped because: kasan: bad access detected
>>
>> Memory state around the buggy address:
>>  ffff8801beca5680: fc fc fc fc fc fc fc fc fb fb fb fb fb fb fb fb
>>  ffff8801beca5700: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
>>>
>>> ffff8801beca5780: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
>>
>>                       ^
>>  ffff8801beca5800: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
>>  ffff8801beca5880: fb fb fb fb fb fb fb fb fb fb fb fb fc fc fc fc
>> ==================================================================
>>
>>
>> ---
>> This bug is generated by a dumb bot. It may contain errors.
>> See https://goo.gl/tpsmEJ for details.
>> Direct all questions to syzkaller@googlegroups.com.
>>
>> syzbot will keep track of this bug report.
>> If you forgot to add the Reported-by tag, once the fix for this bug is
>> merged
>> into any tree, please reply to this email with:
>> #syz fix: exact-commit-title
>> To mark this as a duplicate of another syzbot report, please reply with:
>> #syz dup: exact-subject-of-another-report
>> If it's a one-off invalid bug report, please reply with:
>> #syz invalid
>> Note: if the crash happens again, it will cause creation of a new bug
>> report.
>> Note: all commands must start from beginning of the line in the email body.
>>
>> --
>> 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 syzkaller-bugs+unsubscribe@googlegroups.com.
>> To view this discussion on the web visit
>> https://groups.google.com/d/msgid/syzkaller-bugs/001a1144d6e8ef29870562424c44%40google.com.
>> For more options, visit https://groups.google.com/d/optout.

^ permalink raw reply	[flat|nested] 3+ messages in thread

* Re: KASAN: use-after-free Read in work_is_static_object
  2018-01-08 11:58   ` Dmitry Vyukov
@ 2018-05-09  2:49     ` Eric Biggers
  0 siblings, 0 replies; 3+ messages in thread
From: Eric Biggers @ 2018-05-09  2:49 UTC (permalink / raw)
  To: Dmitry Vyukov
  Cc: syzbot, David Miller, Cong Wang, Tom Herbert, Eric Dumazet,
	Eric Biggers, netdev, LKML, syzkaller-bugs

On Mon, Jan 08, 2018 at 12:58:11PM +0100, 'Dmitry Vyukov' via syzkaller-bugs wrote:
> On Mon, Jan 8, 2018 at 12:55 PM, Dmitry Vyukov <dvyukov@google.com> wrote:
> > On Mon, Jan 8, 2018 at 12:43 PM, syzbot
> > <syzbot+40396d275b34b0dd5dad@syzkaller.appspotmail.com> wrote:
> >> Hello,
> >>
> >> syzkaller hit the following crash on
> >> f66faae2f80a45feafc04ce63ef744ac4b6e8c05
> >> git://git.kernel.org/pub/scm/linux/kernel/git/davem/net-next.git/master
> >> compiler: gcc (GCC) 7.1.1 20170620
> >> .config is attached
> >> Raw console output is attached.
> >> Unfortunately, I don't have any reproducer for this bug yet.
> >>
> >>
> >> IMPORTANT: if you fix the bug, please add the following tag to the commit:
> >> Reported-by: syzbot+40396d275b34b0dd5dad@syzkaller.appspotmail.com
> >> It will help syzbot understand when the bug is fixed. See footer for
> >> details.
> >> If you forward the report, please keep this part and the footer.
> >
> >
> > This looks like an issue in kcm sockets, so +kcm maintainers.
> 
> FTR, guilty file extraction was fixed to ignore kernel/workqueue.c:
> https://github.com/google/syzkaller/commit/1014e5506e35965f3bad13fabb08666134d0b273
> Presumably for bugs in workqueue usually the caller is guilty.
> 
> 
> >> device ip6_vti0 entered promiscuous mode
> >> ==================================================================
> >> BUG: KASAN: use-after-free in constant_test_bit
> >> arch/x86/include/asm/bitops.h:325 [inline]
> >> BUG: KASAN: use-after-free in work_is_static_object+0x39/0x40
> >> kernel/workqueue.c:443
> >> Read of size 8 at addr ffff8801beca5788 by task syz-executor2/12922
> >>
> >> CPU: 0 PID: 12922 Comm: syz-executor2 Not tainted 4.15.0-rc5+ #178
> >> Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS
> >> Google 01/01/2011
> >> Call Trace:
> >>  __dump_stack lib/dump_stack.c:17 [inline]
> >>  dump_stack+0x194/0x257 lib/dump_stack.c:53
> >>  print_address_description+0x73/0x250 mm/kasan/report.c:252
> >>  kasan_report_error mm/kasan/report.c:351 [inline]
> >>  kasan_report+0x25b/0x340 mm/kasan/report.c:409
> >>  __asan_report_load8_noabort+0x14/0x20 mm/kasan/report.c:430
> >>  constant_test_bit arch/x86/include/asm/bitops.h:325 [inline]
> >>  work_is_static_object+0x39/0x40 kernel/workqueue.c:443
> >>  debug_object_activate+0x36f/0x730 lib/debugobjects.c:470
> >>  debug_work_activate kernel/workqueue.c:492 [inline]
> >>  __queue_work+0x163/0x1230 kernel/workqueue.c:1381
> >>  queue_work_on+0x16a/0x1c0 kernel/workqueue.c:1487
> >>  queue_work include/linux/workqueue.h:488 [inline]
> >>  strp_check_rcv+0x25/0x30 net/strparser/strparser.c:552
> >>  kcm_attach net/kcm/kcmsock.c:1439 [inline]
> >>  kcm_attach_ioctl net/kcm/kcmsock.c:1460 [inline]
> >>  kcm_ioctl+0x82f/0x1690 net/kcm/kcmsock.c:1665
> >>  sock_do_ioctl+0x65/0xb0 net/socket.c:956
> >>  sock_ioctl+0x2c2/0x440 net/socket.c:1053
> >>  vfs_ioctl fs/ioctl.c:46 [inline]
> >>  do_vfs_ioctl+0x1b1/0x1520 fs/ioctl.c:686
> >>  SYSC_ioctl fs/ioctl.c:701 [inline]
> >>  SyS_ioctl+0x8f/0xc0 fs/ioctl.c:692
> >>  entry_SYSCALL_64_fastpath+0x23/0x9a
> >> RIP: 0033:0x452ac9
> >> RSP: 002b:00007f1bbd860c58 EFLAGS: 00000212 ORIG_RAX: 0000000000000010
> >> RAX: ffffffffffffffda RBX: 000000000071bea0 RCX: 0000000000452ac9
> >> RDX: 0000000020954ff8 RSI: 00000000000089e0 RDI: 0000000000000017
> >> RBP: 000000000000057b R08: 0000000000000000 R09: 0000000000000000
> >> R10: 0000000000000000 R11: 0000000000000212 R12: 00000000006f6428
> >> R13: 00000000ffffffff R14: 00007f1bbd8616d4 R15: 0000000000000000
> >>
> >> Allocated by task 12922:
> >>  save_stack+0x43/0xd0 mm/kasan/kasan.c:447
> >>  set_track mm/kasan/kasan.c:459 [inline]
> >>  kasan_kmalloc+0xad/0xe0 mm/kasan/kasan.c:551
> >>  kasan_slab_alloc+0x12/0x20 mm/kasan/kasan.c:489
> >>  kmem_cache_alloc+0x12e/0x760 mm/slab.c:3544
> >>  kmem_cache_zalloc include/linux/slab.h:678 [inline]
> >>  kcm_attach net/kcm/kcmsock.c:1394 [inline]
> >>  kcm_attach_ioctl net/kcm/kcmsock.c:1460 [inline]
> >>  kcm_ioctl+0x2d2/0x1690 net/kcm/kcmsock.c:1665
> >>  sock_do_ioctl+0x65/0xb0 net/socket.c:956
> >>  sock_ioctl+0x2c2/0x440 net/socket.c:1053
> >>  vfs_ioctl fs/ioctl.c:46 [inline]
> >>  do_vfs_ioctl+0x1b1/0x1520 fs/ioctl.c:686
> >>  SYSC_ioctl fs/ioctl.c:701 [inline]
> >>  SyS_ioctl+0x8f/0xc0 fs/ioctl.c:692
> >>  entry_SYSCALL_64_fastpath+0x23/0x9a
> >>
> >> Freed by task 12929:
> >>  save_stack+0x43/0xd0 mm/kasan/kasan.c:447
> >>  set_track mm/kasan/kasan.c:459 [inline]
> >>  kasan_slab_free+0x71/0xc0 mm/kasan/kasan.c:524
> >>  __cache_free mm/slab.c:3488 [inline]
> >>  kmem_cache_free+0x83/0x2a0 mm/slab.c:3746
> >>  kcm_unattach+0xe53/0x1510 net/kcm/kcmsock.c:1563
> >>  kcm_unattach_ioctl net/kcm/kcmsock.c:1608 [inline]
> >>  kcm_ioctl+0xe54/0x1690 net/kcm/kcmsock.c:1675
> >>  sock_do_ioctl+0x65/0xb0 net/socket.c:956
> >>  sock_ioctl+0x2c2/0x440 net/socket.c:1053
> >>  vfs_ioctl fs/ioctl.c:46 [inline]
> >>  do_vfs_ioctl+0x1b1/0x1520 fs/ioctl.c:686
> >>  SYSC_ioctl fs/ioctl.c:701 [inline]
> >>  SyS_ioctl+0x8f/0xc0 fs/ioctl.c:692
> >>  entry_SYSCALL_64_fastpath+0x23/0x9a
> >>
> >> The buggy address belongs to the object at ffff8801beca56c0
> >>  which belongs to the cache kcm_psock_cache of size 544
> >> The buggy address is located 200 bytes inside of
> >>  544-byte region [ffff8801beca56c0, ffff8801beca58e0)
> >> The buggy address belongs to the page:
> >> page:000000005180a80a count:1 mapcount:0 mapping:0000000058aa9a5c index:0x0
> >> compound_mapcount: 0
> >> flags: 0x2fffc0000008100(slab|head)
> >> raw: 02fffc0000008100 ffff8801beca40c0 0000000000000000 000000010000000b
> >> raw: ffff8801d31e8a48 ffff8801d31e8a48 ffff8801d3f6a380 0000000000000000
> >> page dumped because: kasan: bad access detected
> >>
> >> Memory state around the buggy address:
> >>  ffff8801beca5680: fc fc fc fc fc fc fc fc fb fb fb fb fb fb fb fb
> >>  ffff8801beca5700: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
> >>>
> >>> ffff8801beca5780: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
> >>
> >>                       ^
> >>  ffff8801beca5800: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
> >>  ffff8801beca5880: fb fb fb fb fb fb fb fb fb fb fb fb fc fc fc fc
> >> ==================================================================
> >>
> >>
> >> ---
> >> This bug is generated by a dumb bot. It may contain errors.
> >> See https://goo.gl/tpsmEJ for details.
> >> Direct all questions to syzkaller@googlegroups.com.
> >>
> >> syzbot will keep track of this bug report.
> >> If you forgot to add the Reported-by tag, once the fix for this bug is
> >> merged
> >> into any tree, please reply to this email with:
> >> #syz fix: exact-commit-title

This only happened 3 times, with no reproducer, and last occurred 105 days ago
(Jan 23, on commit 2310035fa03f6).  It looks *very* similar to
"KASAN: use-after-free Read in get_work_pool"
(https://syzkaller.appspot.com/bug?extid=ea75c0ffcd353d32515f064aaebefc5279e6161e)
which was fixed by commit 2cc683e88c0c99
("kcm: lock lower socket in kcm_attach"),
so I'll make an educated guess and say this one was fixed by that too...

#syz fix: kcm: lock lower socket in kcm_attach

- Eric

^ permalink raw reply	[flat|nested] 3+ messages in thread

end of thread, other threads:[~2018-05-09  2:47 UTC | newest]

Thread overview: 3+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
     [not found] <001a1144d6e8ef29870562424c44@google.com>
2018-01-08 11:55 ` KASAN: use-after-free Read in work_is_static_object Dmitry Vyukov
2018-01-08 11:58   ` Dmitry Vyukov
2018-05-09  2:49     ` Eric Biggers

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