[syzbot] general protection fault in io_commit_cqring (2)

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: 81b1d39f Merge tag '5.12-rc4-smb3' of git://git.samba.org/..
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=10ce6fe6d00000
kernel config: https://syzkaller.appspot.com/x/.config?x=daeff30c2474a60f
dashboard link: https://syzkaller.appspot.com/bug?extid=0e905eb8228070c457a0
syz repro: https://syzkaller.appspot.com/x/repro.syz?x=10e0ed06d00000
C reproducer: https://syzkaller.appspot.com/x/repro.c?x=1144754ed00000

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+0e905e...@syzkaller.appspotmail.com

RBP: 00007ffe05a7c220 R08: 0000000000000001 R09: 0000000000000001
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000003
R13: 431bde82d7b634db R14: 00000000004ae018 R15: 0000000000400488
general protection fault, probably for non-canonical address 0xdffffc0000000018: 0000 [#1] PREEMPT SMP KASAN
KASAN: null-ptr-deref in range [0x00000000000000c0-0x00000000000000c7]
CPU: 1 PID: 8400 Comm: syz-executor278 Not tainted 5.12.0-rc4-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
RIP: 0010:io_commit_cqring+0x37f/0xc10 fs/io_uring.c:1318
Code: 74 08 3c 03 0f 8e fa 05 00 00 48 8d bb c0 00 00 00 41 8b ac 24 00 06 00 00 48 b8 00 00 00 00 00 fc ff df 48 89 fa 48 c1 ea 03 <0f> b6 14 02 48 89 f8 83 e0 07 83 c0 03 38 d0 7c 08 84 d2 0f 85 b7
RSP: 0018:ffffc90001c1fc78 EFLAGS: 00010006
RAX: dffffc0000000000 RBX: 0000000000000000 RCX: 0000000000000000
RDX: 0000000000000018 RSI: ffffffff81db8861 RDI: 00000000000000c0
RBP: 0000000000000000 R08: 0000000000000001 R09: 0000000000000003
R10: fffff52000383f8f R11: 0000000000000000 R12: ffff888018166000
R13: 0000000000000000 R14: 1ffff92000383fab R15: ffff8880181660c0
FS: 00000000006c7300(0000) GS:ffff8880b9d00000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007fd3db1886c0 CR3: 0000000021099000 CR4: 00000000001506e0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
io_kill_timeouts+0x2b5/0x320 fs/io_uring.c:8606
io_ring_ctx_wait_and_kill+0x1da/0x400 fs/io_uring.c:8629
io_uring_create fs/io_uring.c:9572 [inline]
io_uring_setup+0x10da/0x2ae0 fs/io_uring.c:9599
do_syscall_64+0x2d/0x70 arch/x86/entry/common.c:46
entry_SYSCALL_64_after_hwframe+0x44/0xae
RIP: 0033:0x43ffd9
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:00007ffe05a7c208 EFLAGS: 00000246 ORIG_RAX: 00000000000001a9
RAX: ffffffffffffffda RBX: 0000000000000001 RCX: 000000000043ffd9
RDX: 0000000000000020 RSI: 0000000020000080 RDI: 00000000000054ca
RBP: 00007ffe05a7c220 R08: 0000000000000001 R09: 0000000000000001
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000003
R13: 431bde82d7b634db R14: 00000000004ae018 R15: 0000000000400488
Modules linked in:
---[ end trace a0b1f0cfec9b9808 ]---
RIP: 0010:io_commit_cqring+0x37f/0xc10 fs/io_uring.c:1318
Code: 74 08 3c 03 0f 8e fa 05 00 00 48 8d bb c0 00 00 00 41 8b ac 24 00 06 00 00 48 b8 00 00 00 00 00 fc ff df 48 89 fa 48 c1 ea 03 <0f> b6 14 02 48 89 f8 83 e0 07 83 c0 03 38 d0 7c 08 84 d2 0f 85 b7
RSP: 0018:ffffc90001c1fc78 EFLAGS: 00010006
RAX: dffffc0000000000 RBX: 0000000000000000 RCX: 0000000000000000
RDX: 0000000000000018 RSI: ffffffff81db8861 RDI: 00000000000000c0
RBP: 0000000000000000 R08: 0000000000000001 R09: 0000000000000003
R10: fffff52000383f8f R11: 0000000000000000 R12: ffff888018166000
R13: 0000000000000000 R14: 1ffff92000383fab R15: ffff8880181660c0
FS: 00000000006c7300(0000) GS:ffff8880b9d00000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007fd3db1886c0 CR3: 0000000021099000 CR4: 00000000001506e0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400


---
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[syzbot]

syzbot has bisected this issue to:

commit f9d6725bf44a5b9412b5da07e3467100fe2af236
Author: Alexander Lobakin <alob...@pm.me>
Date: Sat Feb 13 14:11:50 2021 +0000

skbuff: use __build_skb_around() in __alloc_skb()

bisection log: https://syzkaller.appspot.com/x/bisect.txt?x=11934b3ad00000
start commit: 81b1d39f Merge tag '5.12-rc4-smb3' of git://git.samba.org/..
git tree: upstream
final oops: https://syzkaller.appspot.com/x/report.txt?x=13934b3ad00000
console output: https://syzkaller.appspot.com/x/log.txt?x=15934b3ad00000

kernel config: https://syzkaller.appspot.com/x/.config?x=daeff30c2474a60f
dashboard link: https://syzkaller.appspot.com/bug?extid=0e905eb8228070c457a0
syz repro: https://syzkaller.appspot.com/x/repro.syz?x=10e0ed06d00000
C reproducer: https://syzkaller.appspot.com/x/repro.c?x=1144754ed00000

Reported-by: syzbot+0e905e...@syzkaller.appspotmail.com
Fixes: f9d6725bf44a ("skbuff: use __build_skb_around() in __alloc_skb()")

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