[syzbot] general protection fault in io_issue_sqe

From: syzbot
Date: Thu Sep 02 2021 - 13:34:41 EST

Hello,

syzbot found the following issue on:

HEAD commit: 9c849ce86e0f Merge tag '5.15-rc-smb3-fixes-part1' of git:/..
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=1292c59d300000
kernel config: https://syzkaller.appspot.com/x/.config?x=bf588afb178273fb
dashboard link: https://syzkaller.appspot.com/bug?extid=de67aa0cf1053e405871
compiler: gcc (Debian 10.2.1-6) 10.2.1 20210110, GNU ld (GNU Binutils for Debian) 2.35.1
syz repro: https://syzkaller.appspot.com/x/repro.syz?x=1681ad75300000
C reproducer: https://syzkaller.appspot.com/x/repro.c?x=12b72083300000

The issue was bisected to:

commit a8295b982c46d4a7c259a4cdd58a2681929068a9
Author: Hao Xu <haoxu@xxxxxxxxxxxxxxxxx>
Date: Fri Aug 27 09:46:09 2021 +0000

io_uring: fix failed linkchain code logic

bisection log: https://syzkaller.appspot.com/x/bisect.txt?x=16d17dde300000
final oops: https://syzkaller.appspot.com/x/report.txt?x=15d17dde300000
console output: https://syzkaller.appspot.com/x/log.txt?x=11d17dde300000

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+de67aa0cf1053e405871@xxxxxxxxxxxxxxxxxxxxxxxxx
Fixes: a8295b982c46 ("io_uring: fix failed linkchain code logic")

general protection fault, probably for non-canonical address 0xdffffc0000000010: 0000 [#1] PREEMPT SMP KASAN
KASAN: null-ptr-deref in range [0x0000000000000080-0x0000000000000087]
CPU: 1 PID: 8426 Comm: syz-executor497 Not tainted 5.14.0-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
RIP: 0010:io_accept fs/io_uring.c:5041 [inline]
RIP: 0010:io_issue_sqe+0x2522/0x6ba0 fs/io_uring.c:6596
Code: 48 c1 ea 03 80 3c 02 00 0f 85 66 42 00 00 48 b8 00 00 00 00 00 fc ff df 4d 8b 27 49 8d bc 24 80 00 00 00 48 89 fa 48 c1 ea 03 <0f> b6 04 02 84 c0 74 08 3c 03 0f 8e 47 42 00 00 45 8b ac 24 80 00
RSP: 0018:ffffc900010dfb48 EFLAGS: 00010202
RAX: dffffc0000000000 RBX: 0000000000000000 RCX: 0000000000000000
RDX: 0000000000000010 RSI: ffffffff81e2c2cd RDI: 0000000000000080
RBP: ffff888016a5179c R08: 0000000000000000 R09: ffffffff81e29ff8
R10: ffffffff81e2c2bf R11: 000000000000000d R12: 0000000000000000
R13: 1ffff11002d4a2f9 R14: 0000000000000003 R15: ffff888016a51780
FS: 0000000000675300(0000) GS:ffff8880b9d00000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f74bb07a6c0 CR3: 0000000026e49000 CR4: 00000000001506e0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
__io_queue_sqe+0x90/0xb50 fs/io_uring.c:6864
io_req_task_submit+0xbf/0x1b0 fs/io_uring.c:2218
tctx_task_work+0x166/0x610 fs/io_uring.c:2143
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: 0033:0x43f069
Code: 28 c3 e8 2a 14 00 00 66 2e 0f 1f 84 00 00 00 00 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 c0 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007ffc12dd2538 EFLAGS: 00000246 ORIG_RAX: 00000000000001aa
RAX: 0000000000000304 RBX: 0000000000000003 RCX: 000000000043f069
RDX: 0000000000000000 RSI: 0000000000000304 RDI: 0000000000000003
RBP: 0000000000403050 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 00000000004030e0
R13: 0000000000000000 R14: 00000000004ac018 R15: 0000000000400488
Modules linked in:
---[ end trace 51fb6b52dc1cb8ce ]---
RIP: 0010:io_accept fs/io_uring.c:5041 [inline]
RIP: 0010:io_issue_sqe+0x2522/0x6ba0 fs/io_uring.c:6596
Code: 48 c1 ea 03 80 3c 02 00 0f 85 66 42 00 00 48 b8 00 00 00 00 00 fc ff df 4d 8b 27 49 8d bc 24 80 00 00 00 48 89 fa 48 c1 ea 03 <0f> b6 04 02 84 c0 74 08 3c 03 0f 8e 47 42 00 00 45 8b ac 24 80 00
RSP: 0018:ffffc900010dfb48 EFLAGS: 00010202
RAX: dffffc0000000000 RBX: 0000000000000000 RCX: 0000000000000000
RDX: 0000000000000010 RSI: ffffffff81e2c2cd RDI: 0000000000000080
RBP: ffff888016a5179c R08: 0000000000000000 R09: ffffffff81e29ff8
R10: ffffffff81e2c2bf R11: 000000000000000d R12: 0000000000000000
R13: 1ffff11002d4a2f9 R14: 0000000000000003 R15: ffff888016a51780
FS: 0000000000675300(0000) GS:ffff8880b9c00000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f544adff000 CR3: 0000000026e49000 CR4: 00000000001506f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
----------------
Code disassembly (best guess):
0: 48 c1 ea 03 shr $0x3,%rdx
4: 80 3c 02 00 cmpb $0x0,(%rdx,%rax,1)
8: 0f 85 66 42 00 00 jne 0x4274
e: 48 b8 00 00 00 00 00 movabs $0xdffffc0000000000,%rax
15: fc ff df
18: 4d 8b 27 mov (%r15),%r12
1b: 49 8d bc 24 80 00 00 lea 0x80(%r12),%rdi
22: 00
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 47 42 00 00 jle 0x4281
3a: 45 rex.RB
3b: 8b .byte 0x8b
3c: ac lods %ds:(%rsi),%al
3d: 24 80 and $0x80,%al


---
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