[syzbot] WARNING in vmx_queue_exception (2)

[syzbot] WARNING in vmx_queue_exception (2)

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit:    57ae8a492116 Merge tag 'driver-core-5.18-rc5' of git://git..
git tree:       upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=16d27d72f00000
kernel config:  https://syzkaller.appspot.com/x/.config?x=d21a72f6016e37e8
dashboard link: https://syzkaller.appspot.com/bug?extid=cfafed3bb76d3e37581b
compiler:       gcc (Debian 10.2.1-6) 10.2.1 20210110, GNU ld (GNU Binutils for Debian) 2.35.2
syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=1202b25af00000
C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=1386a07af00000

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+cfafed3bb76d3e37581b@syzkaller.appspotmail.com

------------[ cut here ]------------
WARNING: CPU: 2 PID: 3674 at arch/x86/kvm/vmx/vmx.c:1628 vmx_queue_exception+0x3e6/0x450 arch/x86/kvm/vmx/vmx.c:1628
Modules linked in:
CPU: 2 PID: 3674 Comm: syz-executor352 Not tainted 5.18.0-rc4-syzkaller-00396-g57ae8a492116 #0
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.14.0-2 04/01/2014
RIP: 0010:vmx_queue_exception+0x3e6/0x450 arch/x86/kvm/vmx/vmx.c:1628
Code: 89 fa 48 c1 ea 03 0f b6 04 02 48 89 fa 83 e2 07 38 d0 7f 04 84 c0 75 6c 44 0f b6 b5 7c 0d 00 00 e9 16 ff ff ff e8 5a 7b 58 00 <0f> 0b e9 87 fd ff ff e8 5e 72 a3 00 e9 b5 fc ff ff e8 54 72 a3 00
RSP: 0018:ffffc90003017b10 EFLAGS: 00010293
RAX: 0000000000000000 RBX: 0000000080000800 RCX: 0000000000000000
RDX: ffff88801d230100 RSI: ffffffff811fe996 RDI: 0000000000000003
RBP: ffff888023464040 R08: 0000000000000000 R09: 0000000000000001
R10: ffffffff811fe71b R11: 0000000000000000 R12: 0000000000000001
R13: 00000000fffffffd R14: 0000000000000000 R15: dffffc0000000000
FS:  0000555555918300(0000) GS:ffff88802cc00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000000000000000 CR3: 00000000235cc000 CR4: 0000000000152ee0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 <TASK>
 kvm_inject_exception arch/x86/kvm/x86.c:9339 [inline]
 inject_pending_event+0x592/0x1480 arch/x86/kvm/x86.c:9350
 vcpu_enter_guest arch/x86/kvm/x86.c:10072 [inline]
 vcpu_run arch/x86/kvm/x86.c:10360 [inline]
 kvm_arch_vcpu_ioctl_run+0xff7/0x6680 arch/x86/kvm/x86.c:10561
 kvm_vcpu_ioctl+0x570/0xf30 arch/x86/kvm/../../../virt/kvm/kvm_main.c:3943
 vfs_ioctl fs/ioctl.c:51 [inline]
 __do_sys_ioctl fs/ioctl.c:870 [inline]
 __se_sys_ioctl fs/ioctl.c:856 [inline]
 __x64_sys_ioctl+0x193/0x200 fs/ioctl.c:856
 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: 0033:0x7effdacd6f49
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:00007ffc580ec718 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 00007effdacd6f49
RDX: 0000000000000000 RSI: 000000000000ae80 RDI: 0000000000000005
RBP: 00007effdac9aa40 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 00007effdac9aad0
R13: 0000000000000000 R14: 0000000000000000 R15: 0000000000000000
 </TASK>


---
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Re: [syzbot] WARNING in vmx_queue_exception (2)

[Sean Christopherson]

On Mon, May 02, 2022, syzbot wrote:
> Hello,
> 
> syzbot found the following issue on:
> 
> HEAD commit:    57ae8a492116 Merge tag 'driver-core-5.18-rc5' of git://git..
> git tree:       upstream
> console output: https://syzkaller.appspot.com/x/log.txt?x=16d27d72f00000
> kernel config:  https://syzkaller.appspot.com/x/.config?x=d21a72f6016e37e8
> dashboard link: https://syzkaller.appspot.com/bug?extid=cfafed3bb76d3e37581b
> compiler:       gcc (Debian 10.2.1-6) 10.2.1 20210110, GNU ld (GNU Binutils for Debian) 2.35.2
> syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=1202b25af00000
> C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=1386a07af00000
> 
> IMPORTANT: if you fix the issue, please add the following tag to the commit:
> Reported-by: syzbot+cfafed3bb76d3e37581b@syzkaller.appspotmail.com
> 
> ------------[ cut here ]------------
> WARNING: CPU: 2 PID: 3674 at arch/x86/kvm/vmx/vmx.c:1628 vmx_queue_exception+0x3e6/0x450 arch/x86/kvm/vmx/vmx.c:1628
> Modules linked in:
> CPU: 2 PID: 3674 Comm: syz-executor352 Not tainted 5.18.0-rc4-syzkaller-00396-g57ae8a492116 #0
> Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.14.0-2 04/01/2014
> RIP: 0010:vmx_queue_exception+0x3e6/0x450 arch/x86/kvm/vmx/vmx.c:1628

Well this is comically straightforward.  Get to invalid guest state and force an
injected exception from userspace.  KVM only bails on a pending exception, because
it's impossible (barring other bugs) to get to an injected exception, but that
obviously fails to account for userspace intervention.  I'll get a patch posted.