Re: WARNING in free_loaded_vmcs

[Eric Biggers]

On Tue, Nov 21, 2017 at 02:00:00AM -0800, syzbot wrote:
> Hello,
> 
> syzkaller hit the following crash on
> 5a3517e009e979f21977d362212b7729c5165d92
> git://git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git/master
> compiler: gcc (GCC) 7.1.1 20170620
> .config is attached
> Raw console output is attached.
> C reproducer is attached
> syzkaller reproducer is attached. See https://goo.gl/kgGztJ
> for information about syzkaller reproducers
> 
> 
> ------------[ cut here ]------------
> WARNING: CPU: 1 PID: 3224 at arch/x86/kvm/vmx.c:3844
> free_loaded_vmcs+0x10f/0x150 arch/x86/kvm/vmx.c:3844
> Kernel panic - not syncing: panic_on_warn set ...
> 
> CPU: 1 PID: 3224 Comm: syzkaller595060 Not tainted 4.14.0-rc7-next-20171103+
> #38
> Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS
> Google 01/01/2011
> Call Trace:
>  __dump_stack lib/dump_stack.c:17 [inline]
>  dump_stack+0x194/0x257 lib/dump_stack.c:53
>  panic+0x1e4/0x41c kernel/panic.c:183
>  __warn+0x1c4/0x1e0 kernel/panic.c:546
>  report_bug+0x211/0x2d0 lib/bug.c:184
>  fixup_bug+0x40/0x90 arch/x86/kernel/traps.c:177
>  do_trap_no_signal arch/x86/kernel/traps.c:211 [inline]
>  do_trap+0x260/0x390 arch/x86/kernel/traps.c:260
>  do_error_trap+0x120/0x390 arch/x86/kernel/traps.c:297
>  do_invalid_op+0x1b/0x20 arch/x86/kernel/traps.c:310
>  invalid_op+0x18/0x20 arch/x86/entry/entry_64.S:906
> RIP: 0010:free_loaded_vmcs+0x10f/0x150 arch/x86/kvm/vmx.c:3844
> RSP: 0018:ffff8801c7f8f470 EFLAGS: 00010293
> RAX: ffff8801c59a8080 RBX: ffff8801c5b3cdd8 RCX: ffffffff8119c79f
> RDX: 0000000000000000 RSI: 0000000000000001 RDI: ffff8801c5b3cde0
> RBP: ffff8801c7f8f488 R08: ffffea0007182460 R09: 0000000000000000
> R10: 0000000000000000 R11: 0000000000000000 R12: ffff8801c6091000
> R13: 0000000000000001 R14: dffffc0000000000 R15: ffffed0038ff1eb2
>  vmx_free_vcpu+0x1d3/0x2c0 arch/x86/kvm/vmx.c:9510
>  kvm_arch_vcpu_free arch/x86/kvm/x86.c:7730 [inline]
>  kvm_free_vcpus arch/x86/kvm/x86.c:8179 [inline]
>  kvm_arch_destroy_vm+0x4b4/0x990 arch/x86/kvm/x86.c:8278
>  kvm_destroy_vm arch/x86/kvm/../../../virt/kvm/kvm_main.c:726 [inline]
>  kvm_put_kvm+0x695/0xde0 arch/x86/kvm/../../../virt/kvm/kvm_main.c:747
>  kvm_vm_release+0x42/0x50 arch/x86/kvm/../../../virt/kvm/kvm_main.c:758
>  __fput+0x333/0x7f0 fs/file_table.c:210
>  ____fput+0x15/0x20 fs/file_table.c:244
>  task_work_run+0x199/0x270 kernel/task_work.c:113
>  exit_task_work include/linux/task_work.h:22 [inline]
>  do_exit+0x9b5/0x1ad0 kernel/exit.c:869
>  do_group_exit+0x149/0x400 kernel/exit.c:972
>  SYSC_exit_group kernel/exit.c:983 [inline]
>  SyS_exit_group+0x1d/0x20 kernel/exit.c:981
>  entry_SYSCALL_64_fastpath+0x1f/0xbe
> RIP: 0033:0x449099
> RSP: 002b:00007fffd06fde68 EFLAGS: 00000202 ORIG_RAX: 00000000000000e7
> RAX: ffffffffffffffda RBX: 0000000000000007 RCX: 0000000000449099
> RDX: 0000000000474231 RSI: 0000000000000000 RDI: 0000000000000000
> RBP: 0000000000000086 R08: 00000000006dd1c0 R09: 0000000000000000
> R10: 00000000006dd144 R11: 0000000000000202 R12: 0000000000000000
> R13: 00007fffd06fde0f R14: 00007fa36c8839c0 R15: 0000000000000000
> Dumping ftrace buffer:
>    (ftrace buffer empty)
> Kernel Offset: disabled
> Rebooting in 86400 seconds..
> 
[...]
> syzbot will keep track of this bug report.
> Once a fix for this bug is committed, please reply to this email with:
> #syz fix: exact-commit-title

Seems this was fixed a while ago (thanks Wanpeng!), so let's mark this fixed:

#syz fix: KVM: VMX: Fix vmx->nested freeing when no SMI handler