[syzbot] general protection fault in __io_queue_sqe

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit:    b9011c7e671d Add linux-next specific files for 20210816
git tree:       linux-next
console output: https://syzkaller.appspot.com/x/log.txt?x=15474781300000
kernel config:  https://syzkaller.appspot.com/x/.config?x=a245d1aa4f055cc1
dashboard link: https://syzkaller.appspot.com/bug?extid=2b85e9379c34945fe38f
compiler:       gcc (Debian 10.2.1-6) 10.2.1 20210110, GNU ld (GNU Binutils for Debian) 2.35.1

Unfortunately, I don't have any reproducer for this issue yet.

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+2b85e9379c34945fe38f@xxxxxxxxxxxxxxxxxxxxxxxxx

general protection fault, probably for non-canonical address 0xdffffc000000000b: 0000 [#1] PREEMPT SMP KASAN
KASAN: null-ptr-deref in range [0x0000000000000058-0x000000000000005f]
CPU: 0 PID: 6232 Comm: syz-executor.1 Not tainted 5.14.0-rc5-next-20210816-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
RIP: 0010:__io_req_set_refcount fs/io_uring.c:1152 [inline]
RIP: 0010:__io_prep_linked_timeout fs/io_uring.c:1348 [inline]
RIP: 0010:io_prep_linked_timeout fs/io_uring.c:1356 [inline]
RIP: 0010:__io_queue_sqe+0x278/0xeb0 fs/io_uring.c:6708
Code: 89 fa 48 c1 ea 03 80 3c 02 00 0f 85 07 0c 00 00 48 b8 00 00 00 00 00 fc ff df 4c 8b 65 70 49 8d 7c 24 58 48 89 fa 48 c1 ea 03 <0f> b6 04 02 84 c0 74 08 3c 03 0f 8e 3e 0b 00 00 45 8b 74 24 58 31
RSP: 0018:ffffc9000a9ffd48 EFLAGS: 00010202
RAX: dffffc0000000000 RBX: 1ffff9200153ffb0 RCX: ffffc9000ba6a000
RDX: 000000000000000b RSI: ffffffff81e1bcbf RDI: 0000000000000058
RBP: ffff888037d15dc0 R08: 0000000000000001 R09: ffff888037d15e1f
R10: ffffed1006fa2bc3 R11: 0000000000000000 R12: 0000000000000000
R13: 0000000000000000 R14: ffff888037d15e30 R15: ffff888037d15e30
FS:  00007fb490054700(0000) GS:ffff8880b9c00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000000000000000 CR3: 00000000388c5000 CR4: 00000000001506f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 io_req_task_submit+0xaa/0x120 fs/io_uring.c:2139
 tctx_task_work+0x106/0x540 fs/io_uring.c:2063
 task_work_run+0xdd/0x1a0 kernel/task_work.c:164
 tracehook_notify_signal include/linux/tracehook.h:212 [inline]
 handle_signal_work kernel/entry/common.c:146 [inline]
 exit_to_user_mode_loop kernel/entry/common.c:172 [inline]
 exit_to_user_mode_prepare+0x256/0x290 kernel/entry/common.c:209
 __syscall_exit_to_user_mode_work kernel/entry/common.c:291 [inline]
 syscall_exit_to_user_mode+0x19/0x60 kernel/entry/common.c:302
 do_syscall_64+0x42/0xb0 arch/x86/entry/common.c:86
 entry_SYSCALL_64_after_hwframe+0x44/0xae
RIP: 0033:0x4665e9
Code: ff ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 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 73 01 c3 48 c7 c1 bc ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007fb490054188 EFLAGS: 00000246 ORIG_RAX: 00000000000001aa
RAX: 0000000000000081 RBX: 000000000056bf80 RCX: 00000000004665e9
RDX: 0000000000000000 RSI: 00000000000045f5 RDI: 0000000000000003
RBP: 00000000004bfcc4 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 000000000056bf80
R13: 00007ffe3ce9ca1f R14: 00007fb490054300 R15: 0000000000022000
Modules linked in:
---[ end trace 221813d58846ad59 ]---
RIP: 0010:__io_req_set_refcount fs/io_uring.c:1152 [inline]
RIP: 0010:__io_prep_linked_timeout fs/io_uring.c:1348 [inline]
RIP: 0010:io_prep_linked_timeout fs/io_uring.c:1356 [inline]
RIP: 0010:__io_queue_sqe+0x278/0xeb0 fs/io_uring.c:6708
Code: 89 fa 48 c1 ea 03 80 3c 02 00 0f 85 07 0c 00 00 48 b8 00 00 00 00 00 fc ff df 4c 8b 65 70 49 8d 7c 24 58 48 89 fa 48 c1 ea 03 <0f> b6 04 02 84 c0 74 08 3c 03 0f 8e 3e 0b 00 00 45 8b 74 24 58 31
RSP: 0018:ffffc9000a9ffd48 EFLAGS: 00010202
RAX: dffffc0000000000 RBX: 1ffff9200153ffb0 RCX: ffffc9000ba6a000
RDX: 000000000000000b RSI: ffffffff81e1bcbf RDI: 0000000000000058
RBP: ffff888037d15dc0 R08: 0000000000000001 R09: ffff888037d15e1f
R10: ffffed1006fa2bc3 R11: 0000000000000000 R12: 0000000000000000
R13: 0000000000000000 R14: ffff888037d15e30 R15: ffff888037d15e30
FS:  00007fb490054700(0000) GS:ffff8880b9d00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000001b3213a000 CR3: 00000000388c5000 CR4: 00000000001506e0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
----------------
Code disassembly (best guess):
   0:	89 fa                	mov    %edi,%edx
   2:	48 c1 ea 03          	shr    $0x3,%rdx
   6:	80 3c 02 00          	cmpb   $0x0,(%rdx,%rax,1)
   a:	0f 85 07 0c 00 00    	jne    0xc17
  10:	48 b8 00 00 00 00 00 	movabs $0xdffffc0000000000,%rax
  17:	fc ff df 
  1a:	4c 8b 65 70          	mov    0x70(%rbp),%r12
  1e:	49 8d 7c 24 58       	lea    0x58(%r12),%rdi
  23:	48 89 fa             	mov    %rdi,%rdx
  26:	48 c1 ea 03          	shr    $0x3,%rdx
  2a:	0f b6 04 02          	movzbl (%rdx,%rax,1),%eax <-- trapping instruction
  2e:	84 c0                	test   %al,%al
  30:	74 08                	je     0x3a
  32:	3c 03                	cmp    $0x3,%al
  34:	0f 8e 3e 0b 00 00    	jle    0xb78
  3a:	45 8b 74 24 58       	mov    0x58(%r12),%r14d
  3f:	31                   	.byte 0x31


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