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

[Dmitry Vyukov]

On Mon, Jan 8, 2018 at 12:43 PM, syzbot
<syzbot+40396d275b34b0dd5dad@xxxxxxxxxxxxxxxxxxxxxxxxx> 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@xxxxxxxxxxxxxxxxxxxxxxxxx
> It will help syzbot understand when the bug is fixed. See footer for
> details.
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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
> ==================================================================
>
>
> ---
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