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

[Tejun Heo]

Hello,

On Thu, Oct 26, 2017 at 09:35:44AM -0700, syzbot wrote:
> 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

Looks like kcm is trying to reuse a work item whose last workqueue has
been destroyed without re-initing it.  A work item needs to be
reinit'd.

Thanks.

-- 
tejun