[syzbot] WARNING in free_loaded_vmcs (3)

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: dd81e1c7d5fb Merge tag 'powerpc-5.17-2' of git://git.kerne..
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=11a31ae0700000
kernel config: https://syzkaller.appspot.com/x/.config?x=916d34c0d501b86
dashboard link: https://syzkaller.appspot.com/bug?extid=8112db3ab20e70d50c31
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=16c7b51fb00000
C reproducer: https://syzkaller.appspot.com/x/repro.c?x=1212815bb00000

Bisection is inconclusive: the issue happens on the oldest tested release.

bisection log: https://syzkaller.appspot.com/x/bisect.txt?x=1736d857b00000
final oops: https://syzkaller.appspot.com/x/report.txt?x=14b6d857b00000
console output: https://syzkaller.appspot.com/x/log.txt?x=10b6d857b00000

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+8112db...@syzkaller.appspotmail.com

------------[ cut here ]------------
WARNING: CPU: 0 PID: 3606 at arch/x86/kvm/vmx/vmx.c:2665 free_loaded_vmcs arch/x86/kvm/vmx/vmx.c:2665 [inline]
WARNING: CPU: 0 PID: 3606 at arch/x86/kvm/vmx/vmx.c:2665 free_loaded_vmcs+0x158/0x1a0 arch/x86/kvm/vmx/vmx.c:2656
Modules linked in:
CPU: 1 PID: 3606 Comm: syz-executor725 Not tainted 5.17.0-rc1-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
RIP: 0010:free_loaded_vmcs arch/x86/kvm/vmx/vmx.c:2665 [inline]
RIP: 0010:free_loaded_vmcs+0x158/0x1a0 arch/x86/kvm/vmx/vmx.c:2656
Code: 81 e8 bc 8c 4c 00 48 89 da 48 b8 00 00 00 00 00 fc ff df 48 c1 ea 03 80 3c 02 00 75 49 48 8b 2b e9 25 ff ff ff e8 38 17 58 00 <0f> 0b eb b3 e8 8f 4d 9f 00 e9 f7 fe ff ff 48 89 df e8 92 4d 9f 00
RSP: 0018:ffffc90001d2f890 EFLAGS: 00010293
RAX: 0000000000000000 RBX: ffff888079c1a2e8 RCX: 0000000000000000
RDX: ffff888021b65700 RSI: ffffffff81204388 RDI: ffff888079c1a2f0
RBP: ffff88807594d000 R08: 0000000000000001 R09: 0000000000000001
R10: ffffffff817ea048 R11: 0000000000000001 R12: 0000000000000000
R13: ffff888079c18000 R14: 0000000000000003 R15: ffffc90001d2f918
FS: 0000000000000000(0000) GS:ffff8880b9c00000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007fc975b8a328 CR3: 000000007f686000 CR4: 00000000003526f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
<TASK>
kvm_arch_vcpu_destroy+0x72/0x2f0 arch/x86/kvm/x86.c:11123
kvm_vcpu_destroy arch/x86/kvm/../../../virt/kvm/kvm_main.c:441 [inline]
kvm_destroy_vcpus+0x11f/0x290 arch/x86/kvm/../../../virt/kvm/kvm_main.c:460
kvm_free_vcpus arch/x86/kvm/x86.c:11564 [inline]
kvm_arch_destroy_vm+0x2e8/0x470 arch/x86/kvm/x86.c:11676
kvm_destroy_vm arch/x86/kvm/../../../virt/kvm/kvm_main.c:1217 [inline]
kvm_put_kvm+0x4fa/0xb00 arch/x86/kvm/../../../virt/kvm/kvm_main.c:1250
kvm_vm_release+0x3f/0x50 arch/x86/kvm/../../../virt/kvm/kvm_main.c:1273
__fput+0x286/0x9f0 fs/file_table.c:311
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
get_signal+0x4b0/0x28c0 kernel/signal.c:2862
arch_do_signal_or_restart+0x2a9/0x1c40 arch/x86/kernel/signal.c:868
handle_signal_work kernel/entry/common.c:148 [inline]
exit_to_user_mode_loop kernel/entry/common.c:172 [inline]
exit_to_user_mode_prepare+0x17d/0x290 kernel/entry/common.c:207
__syscall_exit_to_user_mode_work kernel/entry/common.c:289 [inline]
syscall_exit_to_user_mode+0x19/0x60 kernel/entry/common.c:300
do_syscall_64+0x42/0xb0 arch/x86/entry/common.c:86
entry_SYSCALL_64_after_hwframe+0x44/0xae
RIP: 0033:0x7fc975b35729
Code: Unable to access opcode bytes at RIP 0x7fc975b356ff.
RSP: 002b:00007fc975ae5308 EFLAGS: 00000246 ORIG_RAX: 00000000000000ca
RAX: fffffffffffffe00 RBX: 00007fc975bbe408 RCX: 00007fc975b35729
RDX: 0000000000000000 RSI: 0000000000000080 RDI: 00007fc975bbe408
RBP: 00007fc975bbe400 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 00007fc975bbe40c
R13: 00007fc975b8b0b8 R14: 6d766b2f7665642f R15: 0000000000022000
</TASK>


---
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For information about bisection process see: https://goo.gl/tpsmEJ#bisection
syzbot can test patches for this issue, for details see:
https://goo.gl/tpsmEJ#testing-patches

[Sean Christopherson]

On Mon, Jan 24, 2022, syzbot wrote:
> WARNING: CPU: 0 PID: 3606 at arch/x86/kvm/vmx/vmx.c:2665 free_loaded_vmcs arch/x86/kvm/vmx/vmx.c:2665 [inline]
> WARNING: CPU: 0 PID: 3606 at arch/x86/kvm/vmx/vmx.c:2665 free_loaded_vmcs+0x158/0x1a0 arch/x86/kvm/vmx/vmx.c:2656

KVM gets confused if userspace abuses KVM_SET_VCPU_EVENTS to toggle SMM on/off
while the vCPU is post-VMXON, I'll send a patch.