[syzbot] general protection fault in vhost_iotlb_itree_first

syzbot
2022-02-19T09:18:36Z

Hello,

syzbot found the following issue on:

HEAD commit: 359303076163 tty: n_tty: do not look ahead for EOL charact..
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=16b34b54700000
kernel config: https://syzkaller.appspot.com/x/.config?x=da674567f7b6043d
dashboard link: https://syzkaller.appspot.com/bug?extid=bbb030fc51d6f3c5d067
compiler: gcc (Debian 10.2.1-6) 10.2.1 20210110, GNU ld (GNU Binutils for Debian) 2.35.2

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+bbb030fc51d6f3c5d067@syzkaller.appspotmail.com

general protection fault, probably for non-canonical address 0xdffffc0000000000: 0000 [#1] PREEMPT SMP KASAN
KASAN: null-ptr-deref in range [0x0000000000000000-0x0000000000000007]
CPU: 1 PID: 17981 Comm: vhost-17980 Not tainted 5.17.0-rc4-syzkaller-00052-g359303076163 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
RIP: 0010:vhost_iotlb_itree_iter_first drivers/vhost/iotlb.c:19 [inline]
RIP: 0010:vhost_iotlb_itree_first+0x29/0x280 drivers/vhost/iotlb.c:169
Code: 00 41 57 41 56 41 55 49 89 d5 41 54 55 48 89 fd 53 48 89 f3 e8 e8 eb a0 fa 48 89 ea 48 b8 00 00 00 00 00 fc ff df 48 c1 ea 03 <80> 3c 02 00 0f 85 e8 01 00 00 4c 8b 65 00 4d 85 e4 0f 84 b3 01 00
RSP: 0018:ffffc90004f57ac8 EFLAGS: 00010246
RAX: dffffc0000000000 RBX: 30303030320a0028 RCX: ffffc900103dc000
RDX: 0000000000000000 RSI: ffffffff86d72738 RDI: 0000000000000000
RBP: 0000000000000000 R08: 0000000000000000 R09: 0000000000000002
R10: ffffffff86d62d88 R11: 0000000000000000 R12: ffff8880260e4d68
R13: 303030305f3a3057 R14: dffffc0000000000 R15: 0000000000000000
FS: 0000000000000000(0000) GS:ffff8880b9d00000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f2d46121901 CR3: 000000001d652000 CR4: 00000000003506e0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
<TASK>
translate_desc+0x11e/0x3e0 drivers/vhost/vhost.c:2054
vhost_get_vq_desc+0x662/0x22c0 drivers/vhost/vhost.c:2300
vhost_vsock_handle_tx_kick+0x277/0xa20 drivers/vhost/vsock.c:522
vhost_worker+0x23d/0x3d0 drivers/vhost/vhost.c:372
kthread+0x2e9/0x3a0 kernel/kthread.c:377
ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:295
</TASK>
Modules linked in:
---[ end trace 0000000000000000 ]---
RIP: 0010:vhost_iotlb_itree_iter_first drivers/vhost/iotlb.c:19 [inline]
RIP: 0010:vhost_iotlb_itree_first+0x29/0x280 drivers/vhost/iotlb.c:169
Code: 00 41 57 41 56 41 55 49 89 d5 41 54 55 48 89 fd 53 48 89 f3 e8 e8 eb a0 fa 48 89 ea 48 b8 00 00 00 00 00 fc ff df 48 c1 ea 03 <80> 3c 02 00 0f 85 e8 01 00 00 4c 8b 65 00 4d 85 e4 0f 84 b3 01 00
RSP: 0018:ffffc90004f57ac8 EFLAGS: 00010246
RAX: dffffc0000000000 RBX: 30303030320a0028 RCX: ffffc900103dc000
RDX: 0000000000000000 RSI: ffffffff86d72738 RDI: 0000000000000000
RBP: 0000000000000000 R08: 0000000000000000 R09: 0000000000000002
R10: ffffffff86d62d88 R11: 0000000000000000 R12: ffff8880260e4d68
R13: 303030305f3a3057 R14: dffffc0000000000 R15: 0000000000000000
FS: 0000000000000000(0000) GS:ffff8880b9d00000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f2d449f6718 CR3: 000000001d652000 CR4: 00000000003506e0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
----------------
Code disassembly (best guess):
0: 00 41 57 add %al,0x57(%rcx)
3: 41 56 push %r14
5: 41 55 push %r13
7: 49 89 d5 mov %rdx,%r13
a: 41 54 push %r12
c: 55 push %rbp
d: 48 89 fd mov %rdi,%rbp
10: 53 push %rbx
11: 48 89 f3 mov %rsi,%rbx
14: e8 e8 eb a0 fa callq 0xfaa0ec01
19: 48 89 ea mov %rbp,%rdx
1c: 48 b8 00 00 00 00 00 movabs $0xdffffc0000000000,%rax
23: fc ff df
26: 48 c1 ea 03 shr $0x3,%rdx
* 2a: 80 3c 02 00 cmpb $0x0,(%rdx,%rax,1) <-- trapping instruction
2e: 0f 85 e8 01 00 00 jne 0x21c
34: 4c 8b 65 00 mov 0x0(%rbp),%r12
38: 4d 85 e4 test %r12,%r12
3b: 0f .byte 0xf
3c: 84 .byte 0x84
3d: b3 01 mov $0x1,%bl

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