| Message ID | 20220502221850.131873-1-seanjc@google.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | KVM: VMX: Exit to userspace if vCPU has injected exception and invalid state | expand |
On 5/3/22 00:18, Sean Christopherson wrote: > Exit to userspace with an emulation error if KVM encounters an injected > exception with invalid guest state, in addition to the existing check of > bailing if there's a pending exception (KVM doesn't support emulating > exceptions except when emulating real mode via vm86). > > In theory, KVM should never get to such a situation as KVM is supposed to > exit to userspace before injecting an exception with invalid guest state. > But in practice, userspace can intervene and manually inject an exception > and/or stuff registers to force invalid guest state while a previously > injected exception is awaiting reinjection. > > Fixes: fc4fad79fc3d ("KVM: VMX: Reject KVM_RUN if emulation is required with pending exception") > Reported-by: syzbot+cfafed3bb76d3e37581b@syzkaller.appspotmail.com > Signed-off-by: Sean Christopherson <seanjc@google.com> > --- > arch/x86/kvm/vmx/vmx.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/arch/x86/kvm/vmx/vmx.c b/arch/x86/kvm/vmx/vmx.c > index cf8581978bce..c41f0ac700c7 100644 > --- a/arch/x86/kvm/vmx/vmx.c > +++ b/arch/x86/kvm/vmx/vmx.c > @@ -5465,7 +5465,7 @@ static bool vmx_emulation_required_with_pending_exception(struct kvm_vcpu *vcpu) > struct vcpu_vmx *vmx = to_vmx(vcpu); > > return vmx->emulation_required && !vmx->rmode.vm86_active && > - vcpu->arch.exception.pending; > + (vcpu->arch.exception.pending || vcpu->arch.exception.injected); > } > > static int handle_invalid_guest_state(struct kvm_vcpu *vcpu) > > base-commit: 84e5ffd045f33e4fa32370135436d987478d0bf7 Queued, thanks. Paolo
diff --git a/arch/x86/kvm/vmx/vmx.c b/arch/x86/kvm/vmx/vmx.c index cf8581978bce..c41f0ac700c7 100644 --- a/arch/x86/kvm/vmx/vmx.c +++ b/arch/x86/kvm/vmx/vmx.c @@ -5465,7 +5465,7 @@ static bool vmx_emulation_required_with_pending_exception(struct kvm_vcpu *vcpu) struct vcpu_vmx *vmx = to_vmx(vcpu); return vmx->emulation_required && !vmx->rmode.vm86_active && - vcpu->arch.exception.pending; + (vcpu->arch.exception.pending || vcpu->arch.exception.injected); } static int handle_invalid_guest_state(struct kvm_vcpu *vcpu)
Exit to userspace with an emulation error if KVM encounters an injected exception with invalid guest state, in addition to the existing check of bailing if there's a pending exception (KVM doesn't support emulating exceptions except when emulating real mode via vm86). In theory, KVM should never get to such a situation as KVM is supposed to exit to userspace before injecting an exception with invalid guest state. But in practice, userspace can intervene and manually inject an exception and/or stuff registers to force invalid guest state while a previously injected exception is awaiting reinjection. Fixes: fc4fad79fc3d ("KVM: VMX: Reject KVM_RUN if emulation is required with pending exception") Reported-by: syzbot+cfafed3bb76d3e37581b@syzkaller.appspotmail.com Signed-off-by: Sean Christopherson <seanjc@google.com> --- arch/x86/kvm/vmx/vmx.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) base-commit: 84e5ffd045f33e4fa32370135436d987478d0bf7