Re: [syzbot] kernel BUG in vhost_get_vq_desc

[syzbot <syzbot+3140b17cb44a7b174008@syzkaller.appspotmail.com>]

Hello,

syzbot has tested the proposed patch but the reproducer is still triggering an issue:
WARNING in vhost_dev_cleanup

------------[ cut here ]------------
WARNING: CPU: 1 PID: 4073 at drivers/vhost/vhost.c:718 vhost_dev_cleanup+0x900/0xc20 drivers/vhost/vhost.c:718
Modules linked in:
CPU: 1 PID: 4073 Comm: syz-executor336 Not tainted 5.17.0-rc4-syzkaller-00054-gf71077a4d84b-dirty #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
RIP: 0010:vhost_dev_cleanup+0x900/0xc20 drivers/vhost/vhost.c:718
Code: c7 85 90 01 00 00 00 00 00 00 e8 5b 48 a2 fa 48 89 ef 48 83 c4 28 5b 5d 41 5c 41 5d 41 5e 41 5f e9 35 b1 ff ff e8 40 48 a2 fa <0f> 0b e9 49 ff ff ff 48 8b 7c 24 10 e8 8f da e9 fa e9 93 f7 ff ff
RSP: 0018:ffffc90001fa7ca0 EFLAGS: 00010293
RAX: 0000000000000000 RBX: dffffc0000000000 RCX: 0000000000000000
RDX: ffff88807cadd700 RSI: ffffffff86d695e0 RDI: ffff8880764c00b0
RBP: ffff8880764c0000 R08: 0000000000000000 R09: ffff8880764c00d3
R10: ffffed100ec9801a R11: 0000000000000001 R12: ffff8880764c00d0
R13: ffff8880764c0120 R14: ffff8880764c00d0 R15: 0000000000000002
FS:  0000000000000000(0000) GS:ffff8880b9d00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000000000000002 CR3: 000000000b88e000 CR4: 00000000003506e0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 <TASK>
 vhost_vsock_dev_release+0x3a4/0x4f0 drivers/vhost/vsock.c:778
 __fput+0x286/0x9f0 fs/file_table.c:313
 task_work_run+0xdd/0x1a0 kernel/task_work.c:164
 exit_task_work include/linux/task_work.h:32 [inline]
 do_exit+0xb29/0x2a30 kernel/exit.c:806
 do_group_exit+0xd2/0x2f0 kernel/exit.c:935
 __do_sys_exit_group kernel/exit.c:946 [inline]
 __se_sys_exit_group kernel/exit.c:944 [inline]
 __x64_sys_exit_group+0x3a/0x50 kernel/exit.c:944
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x35/0xb0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x44/0xae
RIP: 0033:0x7fd6d7a48ba9
Code: Unable to access opcode bytes at RIP 0x7fd6d7a48b7f.
RSP: 002b:00007ffcc430a878 EFLAGS: 00000246 ORIG_RAX: 00000000000000e7
RAX: ffffffffffffffda RBX: 00007fd6d7abd330 RCX: 00007fd6d7a48ba9
RDX: 000000000000003c RSI: 00000000000000e7 RDI: 0000000000000000
RBP: 0000000000000000 R08: ffffffffffffffc0 R09: 00007ffcc430aa68
R10: 00007ffcc430aa68 R11: 0000000000000246 R12: 00007fd6d7abd330
R13: 0000000000000001 R14: 0000000000000000 R15: 0000000000000001
 </TASK>


Tested on:

commit:         f71077a4 Merge tag 'mmc-v5.17-rc1-2' of git://git.kern..
git tree:       https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/
console output: https://syzkaller.appspot.com/x/log.txt?x=11dc90ea700000
kernel config:  https://syzkaller.appspot.com/x/.config?x=a78b064590b9f912
dashboard link: https://syzkaller.appspot.com/bug?extid=3140b17cb44a7b174008
compiler:       gcc (Debian 10.2.1-6) 10.2.1 20210110, GNU ld (GNU Binutils for Debian) 2.35.2
patch:          https://syzkaller.appspot.com/x/patch.diff?x=14afd0b6700000