Re: BUG: corrupted list in io_file_get

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

On 28/01/2021 17:25, Jens Axboe wrote:
> On 1/28/21 10:12 AM, Pavel Begunkov wrote:
>> On 28/01/2021 16:58, syzbot wrote:
>>> Hello,
>>>
>>> syzbot found the following issue on:
>>>
>>> HEAD commit:    76c057c8 Merge branch 'parisc-5.11-2' of git://git.kernel...
>>> git tree:       upstream
>>> console output: https://syzkaller.appspot.com/x/log.txt?x=11959454d00000
>>> kernel config:  https://syzkaller.appspot.com/x/.config?x=96b123631a6700e9
>>> dashboard link: https://syzkaller.appspot.com/bug?extid=6879187cf57845801267
>>> compiler:       gcc (GCC) 10.1.0-syz 20200507
>>> syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=12a3872cd00000
>>> C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=16ab17a4d00000
>>>
>>> The issue was bisected to:
>>>
>>> commit 02a13674fa0e8dd326de8b9f4514b41b03d99003
>>> Author: Jens Axboe <axboe@kernel.dk>
>>> Date:   Sat Jan 23 22:49:31 2021 +0000
>>>
>>>     io_uring: account io_uring internal files as REQ_F_INFLIGHT
>>>
>>> bisection log:  https://syzkaller.appspot.com/x/bisect.txt?x=14d1bf44d00000
>>> final oops:     https://syzkaller.appspot.com/x/report.txt?x=16d1bf44d00000
>>> console output: https://syzkaller.appspot.com/x/log.txt?x=12d1bf44d00000
>>>
>>> IMPORTANT: if you fix the issue, please add the following tag to the commit:
>>> Reported-by: syzbot+6879187cf57845801267@syzkaller.appspotmail.com
>>> Fixes: 02a13674fa0e ("io_uring: account io_uring internal files as REQ_F_INFLIGHT")
>>>
>>> list_add double add: new=ffff888017eaa080, prev=ffff88801a9cb520, next=ffff888017eaa080.
>>> ------------[ cut here ]------------
>>> kernel BUG at lib/list_debug.c:29!
>>> invalid opcode: 0000 [#1] PREEMPT SMP KASAN
>>> CPU: 0 PID: 8481 Comm: syz-executor556 Not tainted 5.11.0-rc5-syzkaller #0
>>> Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
>>> RIP: 0010:__list_add_valid.cold+0x26/0x3c lib/list_debug.c:29
>>> Code: 04 c3 fb fa 4c 89 e1 48 c7 c7 e0 de 9e 89 e8 9e 43 f3 ff 0f 0b 48 89 f2 4c 89 e1 48 89 ee 48 c7 c7 20 e0 9e 89 e8 87 43 f3 ff <0f> 0b 48 89 f1 48 c7 c7 a0 df 9e 89 4c 89 e6 e8 73 43 f3 ff 0f 0b
>>> RSP: 0018:ffffc90000fef938 EFLAGS: 00010086
>>> RAX: 0000000000000058 RBX: ffff888017eaa000 RCX: 0000000000000000
>>> RDX: ffff88801f3ed340 RSI: ffffffff815b6285 RDI: fffff520001fdf19
>>> RBP: ffff888017eaa080 R08: 0000000000000058 R09: 0000000000000000
>>> R10: ffffffff815af45e R11: 0000000000000000 R12: ffff888017eaa080
>>> R13: ffff888014901900 R14: ffff88801a9cb000 R15: ffff88801a9cb520
>>> FS:  0000000002395880(0000) GS:ffff8880b9e00000(0000) knlGS:0000000000000000
>>> CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
>>> CR2: 00007ff04f95b6c0 CR3: 000000001a4f2000 CR4: 0000000000350ef0
>>> Call Trace:
>>>  __list_add include/linux/list.h:67 [inline]
>>>  list_add include/linux/list.h:86 [inline]
>>>  io_file_get+0x8cc/0xdb0 fs/io_uring.c:6466
>>>  __io_splice_prep+0x1bc/0x530 fs/io_uring.c:3866
>>>  io_splice_prep fs/io_uring.c:3920 [inline]
>>>  io_req_prep+0x3546/0x4e80 fs/io_uring.c:6081
>>>  io_queue_sqe+0x609/0x10d0 fs/io_uring.c:6628
>>>  io_submit_sqe fs/io_uring.c:6705 [inline]
>>>  io_submit_sqes+0x1495/0x2720 fs/io_uring.c:6953
>>>  __do_sys_io_uring_enter+0x107d/0x1f30 fs/io_uring.c:9353
>>>  do_syscall_64+0x2d/0x70 arch/x86/entry/common.c:46
>>>  entry_SYSCALL_64_after_hwframe+0x44/0xa9
>>> RIP: 0033:0x440569
>>> Code: 18 89 d0 c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 00 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 0f 83 7b 13 fc ff c3 66 2e 0f 1f 84 00 00 00 00
>>> RSP: 002b:00007ffe38c5c5a8 EFLAGS: 00000246 ORIG_RAX: 00000000000001aa
>>> RAX: ffffffffffffffda RBX: 0000000000401e00 RCX: 0000000000440569
>>> RDX: 0000000000000000 RSI: 000000000000450c RDI: 0000000000000004
>>> RBP: 00000000006ca018 R08: 0000000000000000 R09: 0000000000000000
>>> R10: 0000000000000002 R11: 0000000000000246 R12: 0000000000401d70
>>> R13: 0000000000401e00 R14: 0000000000000000 R15: 0000000000000000
>>> Modules linked in:
>>> ---[ end trace 3c68392a0f24e7a0 ]---
>>> RIP: 0010:__list_add_valid.cold+0x26/0x3c lib/list_debug.c:29
>>> Code: 04 c3 fb fa 4c 89 e1 48 c7 c7 e0 de 9e 89 e8 9e 43 f3 ff 0f 0b 48 89 f2 4c 89 e1 48 89 ee 48 c7 c7 20 e0 9e 89 e8 87 43 f3 ff <0f> 0b 48 89 f1 48 c7 c7 a0 df 9e 89 4c 89 e6 e8 73 43 f3 ff 0f 0b
>>> RSP: 0018:ffffc90000fef938 EFLAGS: 00010086
>>> RAX: 0000000000000058 RBX: ffff888017eaa000 RCX: 0000000000000000
>>> RDX: ffff88801f3ed340 RSI: ffffffff815b6285 RDI: fffff520001fdf19
>>> RBP: ffff888017eaa080 R08: 0000000000000058 R09: 0000000000000000
>>> R10: ffffffff815af45e R11: 0000000000000000 R12: ffff888017eaa080
>>> R13: ffff888014901900 R14: ffff88801a9cb000 R15: ffff88801a9cb520
>>> FS:  0000000002395880(0000) GS:ffff8880b9e00000(0000) knlGS:0000000000000000
>>> CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
>>> CR2: 00007ff04f95b6c0 CR3: 000000001a4f2000 CR4: 0000000000350ef0
>>
>> This one is simple
>>
>> diff --git a/fs/io_uring.c b/fs/io_uring.c
>> index ae388cc52843..39ae1f821cef 100644
>> --- a/fs/io_uring.c
>> +++ b/fs/io_uring.c
>> @@ -6460,7 +6460,8 @@ static struct file *io_file_get(struct io_submit_state *state,
>>  		file = __io_file_get(state, fd);
>>  	}
>>  
>> -	if (file && file->f_op == &io_uring_fops) {
>> +	if (file && file->f_op == &io_uring_fops &&
>> +	    !(req->flags & REQ_F_INFLIGHT)) {
>>  		io_req_init_async(req);
>>  		req->flags |= REQ_F_INFLIGHT;
> 
> Curious, how is it marked in-flight already? Ah it's splice... Pavel,

Yeah, splice was handled automatically in the end...

> can you send the fix for this one?

sure, in an hour


-- 
Pavel Begunkov