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

[Dmitry Vyukov]

On Thu, Oct 26, 2017 at 6:35 PM, syzbot
<bot+ea75c0ffcd353d32515f064aaebefc5279e6161e@xxxxxxxxxxxxxxxxxxxxxxxxx>
wrote:
> Hello,
>
> syzkaller hit the following crash on
> ad9a19d003703ae06a6e8efc64cf26a939d9e84d
> 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.
>
> syzkaller reproducer is attached. See https://goo.gl/kgGztJ
> for information about syzkaller reproducers

This also happened on net-next 49ca1943a7adb429b11b8e05d81bc821694b76c7

> BUG: KASAN: use-after-free in __read_once_size include/linux/compiler.h:276
> [inline]
> BUG: KASAN: use-after-free in atomic64_read
> arch/x86/include/asm/atomic64_64.h:21 [inline]
> BUG: KASAN: use-after-free in atomic_long_read
> include/asm-generic/atomic-long.h:44 [inline]
> BUG: KASAN: use-after-free in get_work_pool+0x1c2/0x1e0
> kernel/workqueue.c:709
> Read of size 8 at addr ffff8801cc58c378 by task syz-executor5/21326
>
> CPU: 1 PID: 21326 Comm: syz-executor5 Not tainted 4.13.0+ #43
> Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS
> Google 01/01/2011
> Call Trace:
>  __dump_stack lib/dump_stack.c:16 [inline]
>  dump_stack+0x194/0x257 lib/dump_stack.c:52
>  print_address_description+0x73/0x250 mm/kasan/report.c:252
>  kasan_report_error mm/kasan/report.c:351 [inline]
>  kasan_report+0x24e/0x340 mm/kasan/report.c:409
>  __asan_report_load8_noabort+0x14/0x20 mm/kasan/report.c:430
>  __read_once_size include/linux/compiler.h:276 [inline]
>  atomic64_read arch/x86/include/asm/atomic64_64.h:21 [inline]
>  atomic_long_read include/asm-generic/atomic-long.h:44 [inline]
>  get_work_pool+0x1c2/0x1e0 kernel/workqueue.c:709
>  __queue_work+0x235/0x1150 kernel/workqueue.c:1401
>  queue_work_on+0x16a/0x1c0 kernel/workqueue.c:1486
>  queue_work include/linux/workqueue.h:489 [inline]
>  strp_check_rcv+0x25/0x30 net/strparser/strparser.c:553
>  kcm_attach net/kcm/kcmsock.c:1439 [inline]
>  kcm_attach_ioctl net/kcm/kcmsock.c:1460 [inline]
>  kcm_ioctl+0x826/0x1610 net/kcm/kcmsock.c:1695
>  sock_do_ioctl+0x65/0xb0 net/socket.c:961
>  sock_ioctl+0x2c2/0x440 net/socket.c:1058
>  vfs_ioctl fs/ioctl.c:45 [inline]
>  do_vfs_ioctl+0x1b1/0x1530 fs/ioctl.c:685
>  SYSC_ioctl fs/ioctl.c:700 [inline]
>  SyS_ioctl+0x8f/0xc0 fs/ioctl.c:691
>  entry_SYSCALL_64_fastpath+0x1f/0xbe
> RIP: 0033:0x451e59
> RSP: 002b:00007f95185c3c08 EFLAGS: 00000216 ORIG_RAX: 0000000000000010
> RAX: ffffffffffffffda RBX: 0000000000718160 RCX: 0000000000451e59
> RDX: 00000000209b9000 RSI: 00000000000089e0 RDI: 000000000000000a
> RBP: 0000000000000082 R08: 0000000000000000 R09: 0000000000000000
> R10: 0000000000000000 R11: 0000000000000216 R12: 00000000004bb657
> R13: 00000000ffffffff R14: 0000000000000002 R15: 0000000000000001
>
> Allocated by task 21326:
>  save_stack_trace+0x16/0x20 arch/x86/kernel/stacktrace.c:59
>  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:3561
>  kmem_cache_zalloc include/linux/slab.h:656 [inline]
>  kcm_attach net/kcm/kcmsock.c:1394 [inline]
>  kcm_attach_ioctl net/kcm/kcmsock.c:1460 [inline]
>  kcm_ioctl+0x2d1/0x1610 net/kcm/kcmsock.c:1695
>  sock_do_ioctl+0x65/0xb0 net/socket.c:961
>  sock_ioctl+0x2c2/0x440 net/socket.c:1058
>  vfs_ioctl fs/ioctl.c:45 [inline]
>  do_vfs_ioctl+0x1b1/0x1530 fs/ioctl.c:685
>  SYSC_ioctl fs/ioctl.c:700 [inline]
>  SyS_ioctl+0x8f/0xc0 fs/ioctl.c:691
>  entry_SYSCALL_64_fastpath+0x1f/0xbe
>
> Freed by task 21329:
>  save_stack_trace+0x16/0x20 arch/x86/kernel/stacktrace.c:59
>  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:3503 [inline]
>  kmem_cache_free+0x77/0x280 mm/slab.c:3763
>  kcm_unattach+0xe50/0x1510 net/kcm/kcmsock.c:1563
>  kcm_unattach_ioctl net/kcm/kcmsock.c:1608 [inline]
>  kcm_ioctl+0xdf0/0x1610 net/kcm/kcmsock.c:1705
>  sock_do_ioctl+0x65/0xb0 net/socket.c:961
>  sock_ioctl+0x2c2/0x440 net/socket.c:1058
>  vfs_ioctl fs/ioctl.c:45 [inline]
>  do_vfs_ioctl+0x1b1/0x1530 fs/ioctl.c:685
>  SYSC_ioctl fs/ioctl.c:700 [inline]
>  SyS_ioctl+0x8f/0xc0 fs/ioctl.c:691
>  entry_SYSCALL_64_fastpath+0x1f/0xbe
>
> The buggy address belongs to the object at ffff8801cc58c240
>  which belongs to the cache kcm_psock_cache of size 664
> The buggy address is located 312 bytes inside of
>  664-byte region [ffff8801cc58c240, ffff8801cc58c4d8)
> The buggy address belongs to the page:
> page:ffffea0007316300 count:1 mapcount:0 mapping:ffff8801cc58c240 index:0x0
> compound_mapcount: 0
> flags: 0x200000000008100(slab|head)
> raw: 0200000000008100 ffff8801cc58c240 0000000000000000 0000000100000009
> raw: ffffea000732f520 ffffea0007314ca0 ffff8801d2866e40 0000000000000000
> page dumped because: kasan: bad access detected
>
> Memory state around the buggy address:
>  ffff8801cc58c200: fc fc fc fc fc fc fc fc fb fb fb fb fb fb fb fb
>  ffff8801cc58c280: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
>>
>> ffff8801cc58c300: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
>
>                                                                 ^
>  ffff8801cc58c380: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
>  ffff8801cc58c400: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
> ==================================================================
>
>
> ---
> This bug is generated by a dumb bot. It may contain errors.
> See https://goo.gl/tpsmEJ for details.
> Direct all questions to syzkaller@xxxxxxxxxxxxxxxxx
>
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