Re: WARNING in io_uring_cancel_task_requests

[Pavel Begunkov <asml.silence@gmail.com>]

On 28/01/2021 16:59, syzbot wrote:
> Hello,
> 
> syzbot found the following issue on:
> 
> HEAD commit:    d03154e8 Add linux-next specific files for 20210128
> git tree:       linux-next
> console output: https://syzkaller.appspot.com/x/log.txt?x=159d08a0d00000
> kernel config:  https://syzkaller.appspot.com/x/.config?x=6953ffb584722a1
> dashboard link: https://syzkaller.appspot.com/bug?extid=3e3d9bd0c6ce9efbc3ef
> compiler:       gcc (GCC) 10.1.0-syz 20200507
> 
> Unfortunately, I don't have any reproducer for this issue yet.

This is not interesting either, we can just kill the warning, there
is a better one queued for 5.12.

I'll send patches for both reports later.

> 
> IMPORTANT: if you fix the issue, please add the following tag to the commit:
> Reported-by: syzbot+3e3d9bd0c6ce9efbc3ef@syzkaller.appspotmail.com
> 
> ------------[ cut here ]------------
> WARNING: CPU: 0 PID: 21359 at fs/io_uring.c:9042 io_uring_cancel_task_requests+0xe55/0x10c0 fs/io_uring.c:9042
> Modules linked in:
> CPU: 0 PID: 21359 Comm: syz-executor.0 Not tainted 5.11.0-rc5-next-20210128-syzkaller #0
> Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
> RIP: 0010:io_uring_cancel_task_requests+0xe55/0x10c0 fs/io_uring.c:9042
> Code: 00 00 e9 1c fe ff ff 48 8b 7c 24 18 e8 f4 b4 da ff e9 f2 fc ff ff 48 8b 7c 24 18 e8 e5 b4 da ff e9 64 f2 ff ff e8 eb 16 97 ff <0f> 0b e9 ed f2 ff ff e8 df b4 da ff e9 c8 f5 ff ff 4c 89 ef e8 52
> RSP: 0018:ffffc9000c5a7950 EFLAGS: 00010293
> RAX: 0000000000000000 RBX: ffff88806e79f000 RCX: 0000000000000000
> RDX: ffff88806c9d5400 RSI: ffffffff81dbfe65 RDI: ffff88806e79f0d0
> RBP: ffff88806e79f0e8 R08: 0000000000000000 R09: ffff88806c9d5407
> R10: ffffffff81dbf0df R11: 0000000000000000 R12: ffff88806e79f000
> R13: ffff88806c9d5400 R14: ffff88801cdbb800 R15: ffff88802a151018
> FS:  0000000000000000(0000) GS:ffff8880b9f00000(0000) knlGS:0000000000000000
> CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
> CR2: 0000000000749138 CR3: 0000000011ffd000 CR4: 00000000001506e0
> DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
> DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
> Call Trace:
>  io_uring_flush+0x47b/0x6e0 fs/io_uring.c:9227
>  filp_close+0xb4/0x170 fs/open.c:1295
>  close_files fs/file.c:403 [inline]
>  put_files_struct fs/file.c:418 [inline]
>  put_files_struct+0x1cc/0x350 fs/file.c:415
>  exit_files+0x7e/0xa0 fs/file.c:435
>  do_exit+0xc22/0x2ae0 kernel/exit.c:820
>  do_group_exit+0x125/0x310 kernel/exit.c:922
>  get_signal+0x427/0x20f0 kernel/signal.c:2773
>  arch_do_signal_or_restart+0x2a8/0x1eb0 arch/x86/kernel/signal.c:811
>  handle_signal_work kernel/entry/common.c:147 [inline]
>  exit_to_user_mode_loop kernel/entry/common.c:171 [inline]
>  exit_to_user_mode_prepare+0x148/0x250 kernel/entry/common.c:201
>  __syscall_exit_to_user_mode_work kernel/entry/common.c:291 [inline]
>  syscall_exit_to_user_mode+0x19/0x50 kernel/entry/common.c:302
>  entry_SYSCALL_64_after_hwframe+0x44/0xa9
> RIP: 0033:0x45e219
> Code: Unable to access opcode bytes at RIP 0x45e1ef.
> RSP: 002b:00007f33ed289be8 EFLAGS: 00000206 ORIG_RAX: 00000000000001a9
> RAX: 0000000000000004 RBX: 0000000020000200 RCX: 000000000045e219
> RDX: 0000000020ff8000 RSI: 0000000020000200 RDI: 0000000000002d38
> RBP: 000000000119c080 R08: 00000000200002c0 R09: 00000000200002c0
> R10: 0000000020000280 R11: 0000000000000206 R12: 0000000020ff8000
> R13: 0000000020ff1000 R14: 00000000200002c0 R15: 0000000020000280
> 
> 
> ---
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> 
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> 

-- 
Pavel Begunkov