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;
 


-- 
Pavel Begunkov