[syzbot] general protection fault in io_kill_timeouts

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: b61581ae229d Add linux-next specific files for 20220323
git tree: linux-next
console output: https://syzkaller.appspot.com/x/log.txt?x=17bbb75b700000
kernel config: https://syzkaller.appspot.com/x/.config?x=def28433baf109ed
dashboard link: https://syzkaller.appspot.com/bug?extid=f252f28df734e8521387
compiler: gcc (Debian 10.2.1-6) 10.2.1 20210110, GNU ld (GNU Binutils for Debian) 2.35.2
syz repro: https://syzkaller.appspot.com/x/repro.syz?x=117d3a43700000
C reproducer: https://syzkaller.appspot.com/x/repro.c?x=15538925700000

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+f252f2...@syzkaller.appspotmail.com

RDX: 0000000000000f90 RSI: 00000000200000c0 RDI: 00000000000078af
RBP: 00007fffd1ad3f90 R08: 0000000000000001 R09: 0000000000000001
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000003
R13: 431bde82d7b634db R14: 0000000000000000 R15: 0000000000000000
</TASK>
general protection fault, probably for non-canonical address 0xdffffc0000000018: 0000 [#1] PREEMPT SMP KASAN
KASAN: null-ptr-deref in range [0x00000000000000c0-0x00000000000000c7]
CPU: 0 PID: 3589 Comm: syz-executor273 Tainted: G W 5.17.0-next-20220323-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
RIP: 0010:io_commit_cqring fs/io_uring.c:1812 [inline]
RIP: 0010:io_kill_timeouts+0x267/0x2ce fs/io_uring.c:10297
Code: 74 09 3c 03 7f 05 e8 c5 ca a7 f8 49 8d bc 24 c0 00 00 00 b8 ff ff 37 00 44 8b ad 40 03 00 00 48 89 fa 48 c1 e0 2a 48 c1 ea 03 <8a> 14 02 48 89 f8 83 e0 07 83 c0 03 38 d0 7c 09 84 d2 74 05 e8 fd
RSP: 0018:ffffc9000399fcf8 EFLAGS: 00010206
RAX: dffffc0000000000 RBX: 0000000000000000 RCX: 0000000000000000
RDX: 0000000000000018 RSI: ffffffff817ef121 RDI: 00000000000000c0
RBP: ffff888011a75000 R08: 0000000000000000 R09: 0000000000000000
R10: ffffffff817ef108 R11: 0000000000000000 R12: 0000000000000000
R13: 0000000000000000 R14: ffff888011a75040 R15: 0000000000000001
FS: 0000555557264300(0000) GS:ffff8880b9c00000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 000055a52ec10058 CR3: 0000000024024000 CR4: 00000000003506f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
<TASK>
io_ring_ctx_wait_and_kill+0x1c2/0x327 fs/io_uring.c:10317
io_uring_create fs/io_uring.c:11385 [inline]
io_uring_setup.cold+0x10a3/0x263b fs/io_uring.c:11412
do_syscall_x64 arch/x86/entry/common.c:50 [inline]
do_syscall_64+0x35/0x80 arch/x86/entry/common.c:80
entry_SYSCALL_64_after_hwframe+0x44/0xae
RIP: 0033:0x7f85ced00069
Code: 28 00 00 00 75 05 48 83 c4 28 c3 e8 b1 14 00 00 90 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 73 01 c3 48 c7 c1 c0 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007fffd1ad3f78 EFLAGS: 00000246 ORIG_RAX: 00000000000001a9
RAX: ffffffffffffffda RBX: 0000000000000001 RCX: 00007f85ced00069
RDX: 0000000000000f90 RSI: 00000000200000c0 RDI: 00000000000078af
RBP: 00007fffd1ad3f90 R08: 0000000000000001 R09: 0000000000000001
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000003
R13: 431bde82d7b634db R14: 0000000000000000 R15: 0000000000000000
</TASK>
Modules linked in:
---[ end trace 0000000000000000 ]---
RIP: 0010:io_commit_cqring fs/io_uring.c:1812 [inline]
RIP: 0010:io_kill_timeouts+0x267/0x2ce fs/io_uring.c:10297
Code: 74 09 3c 03 7f 05 e8 c5 ca a7 f8 49 8d bc 24 c0 00 00 00 b8 ff ff 37 00 44 8b ad 40 03 00 00 48 89 fa 48 c1 e0 2a 48 c1 ea 03 <8a> 14 02 48 89 f8 83 e0 07 83 c0 03 38 d0 7c 09 84 d2 74 05 e8 fd
RSP: 0018:ffffc9000399fcf8 EFLAGS: 00010206
RAX: dffffc0000000000 RBX: 0000000000000000 RCX: 0000000000000000
RDX: 0000000000000018 RSI: ffffffff817ef121 RDI: 00000000000000c0
RBP: ffff888011a75000 R08: 0000000000000000 R09: 0000000000000000
R10: ffffffff817ef108 R11: 0000000000000000 R12: 0000000000000000
R13: 0000000000000000 R14: ffff888011a75040 R15: 0000000000000001
FS: 0000555557264300(0000) GS:ffff8880b9c00000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 000055a52ec10058 CR3: 0000000024024000 CR4: 00000000003506f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
----------------
Code disassembly (best guess):
0: 74 09 je 0xb
2: 3c 03 cmp $0x3,%al
4: 7f 05 jg 0xb
6: e8 c5 ca a7 f8 callq 0xf8a7cad0
b: 49 8d bc 24 c0 00 00 lea 0xc0(%r12),%rdi
12: 00
13: b8 ff ff 37 00 mov $0x37ffff,%eax
18: 44 8b ad 40 03 00 00 mov 0x340(%rbp),%r13d
1f: 48 89 fa mov %rdi,%rdx
22: 48 c1 e0 2a shl $0x2a,%rax
26: 48 c1 ea 03 shr $0x3,%rdx
* 2a: 8a 14 02 mov (%rdx,%rax,1),%dl <-- trapping instruction
2d: 48 89 f8 mov %rdi,%rax
30: 83 e0 07 and $0x7,%eax
33: 83 c0 03 add $0x3,%eax
36: 38 d0 cmp %dl,%al
38: 7c 09 jl 0x43
3a: 84 d2 test %dl,%dl
3c: 74 05 je 0x43
3e: e8 .byte 0xe8
3f: fd std


---
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syzbot can test patches for this issue, for details see:
https://goo.gl/tpsmEJ#testing-patches

[syzbot]

syzbot has bisected this issue to:

commit c9be622494c012d56c71e00cb90be841820c3e34
Author: Pavel Begunkov <asml.s...@gmail.com>
Date: Mon Mar 21 22:02:20 2022 +0000

io_uring: remove extra ifs around io_commit_cqring

bisection log: https://syzkaller.appspot.com/x/bisect.txt?x=15a04739700000
start commit: b61581ae229d Add linux-next specific files for 20220323
git tree: linux-next
final oops: https://syzkaller.appspot.com/x/report.txt?x=17a04739700000
console output: https://syzkaller.appspot.com/x/log.txt?x=13a04739700000

kernel config: https://syzkaller.appspot.com/x/.config?x=def28433baf109ed
dashboard link: https://syzkaller.appspot.com/bug?extid=f252f28df734e8521387

syz repro: https://syzkaller.appspot.com/x/repro.syz?x=117d3a43700000
C reproducer: https://syzkaller.appspot.com/x/repro.c?x=15538925700000

Reported-by: syzbot+f252f2...@syzkaller.appspotmail.com
Fixes: c9be622494c0 ("io_uring: remove extra ifs around io_commit_cqring")

For information about bisection process see: https://goo.gl/tpsmEJ#bisection

[Pavel Begunkov]

On 3/23/22 18:47, syzbot wrote:
> syzbot has bisected this issue to:
>
> commit c9be622494c012d56c71e00cb90be841820c3e34
> Author: Pavel Begunkov <asml.s...@gmail.com>
> Date: Mon Mar 21 22:02:20 2022 +0000
>
> io_uring: remove extra ifs around io_commit_cqring

Already found and fixed something pretty similar

#syz test: git://git.kernel.dk/linux-block for-5.18/io_uring

> bisection log: https://syzkaller.appspot.com/x/bisect.txt?x=15a04739700000
> start commit: b61581ae229d Add linux-next specific files for 20220323
> git tree: linux-next
> final oops: https://syzkaller.appspot.com/x/report.txt?x=17a04739700000
> console output: https://syzkaller.appspot.com/x/log.txt?x=13a04739700000
> kernel config: https://syzkaller.appspot.com/x/.config?x=def28433baf109ed
> dashboard link: https://syzkaller.appspot.com/bug?extid=f252f28df734e8521387
> syz repro: https://syzkaller.appspot.com/x/repro.syz?x=117d3a43700000
> C reproducer: https://syzkaller.appspot.com/x/repro.c?x=15538925700000
>
> Reported-by: syzbot+f252f2...@syzkaller.appspotmail.com
> Fixes: c9be622494c0 ("io_uring: remove extra ifs around io_commit_cqring")
>
> For information about bisection process see: https://goo.gl/tpsmEJ#bisection

--
Pavel Begunkov

[syzbot]

Hello,

syzbot has tested the proposed patch and the reproducer did not trigger any issue:

Reported-and-tested-by: syzbot+f252f2...@syzkaller.appspotmail.com

Tested on:

commit: 8a3e8ee5 io_uring: add flag for disabling provided buf..
git tree: git://git.kernel.dk/linux-block for-5.18/io_uring
kernel config: https://syzkaller.appspot.com/x/.config?x=173877d7a6cb7387

dashboard link: https://syzkaller.appspot.com/bug?extid=f252f28df734e8521387
compiler: gcc (Debian 10.2.1-6) 10.2.1 20210110, GNU ld (GNU Binutils for Debian) 2.35.2

Note: no patches were applied.
Note: testing is done by a robot and is best-effort only.

[syzbot]

Auto-closing this bug as obsolete.
No recent activity, existing reproducers are no longer triggering the issue.