Re: KASAN: use-after-free Read in do_general_protection

[Dmitry Vyukov]

On Mon, May 28, 2018 at 1:25 PM, Paolo Bonzini <pbonzini@xxxxxxxxxx> wrote:
> On 26/05/2018 11:29, Dmitry Vyukov wrote:
>> KASAN: stack-out-of-bounds Read in do_general_protection
>> KASAN: slab-out-of-bounds Read in vmx_vcpu_run
>> KASAN: use-after-scope Read in vmx_vcpu_run
>> KASAN: stack-out-of-bounds Write in notify_die
>>
>> See full info at:
>> https://syzkaller.appspot.com/bug?extid=a1264132fc103340628f
>>
>>
>> There seems to be 2 problems:
>>
>> 1. msr_write_intercepted doing something notoriously bad.
>
> The faulting line is
>
>         msr_bitmap = to_vmx(vcpu)->loaded_vmcs->msr_bitmap;
>
> so I suppose to_vmx(vcpu)->loaded_vmcs is bogus?  That seems like "just"
> a corruption of the struct kvm_vcpu, because the loaded_vmcs field is
> pointing elsewhere inside the same struct.

This is reproducible and the reproducer only uses KVM syscalls. So it
seems that KVM corrupts itself. Perhaps it's KVM_SET_MSRS that messes
things?