Userspace should not be able to inject an invalid exception into a kvm
guest via KVM_SET_VCPU_EVENTS, nor should it be able to convert a
valid pending exception to an invalid one via KVM_SET_SREGS.
In particular, only certain exceptions deliver an error code in
protected mode, and no exception delivers an error code in
real-address mode.
Reported-by: syzbot <syzkaller@xxxxxxxxxxxxxxxx>
Signed-off-by: Jim Mattson <jmattson@xxxxxxxxxx>
Reviewed-by: Marc Orr <marcorr@xxxxxxxxxx>
---
arch/x86/kvm/x86.c | 16 ++++++++++++++++
1 file changed, 16 insertions(+)
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index 4ab569171ad1..b67a664b1d7b 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -3423,6 +3423,14 @@ static int kvm_vcpu_ioctl_x86_set_vcpu_events(struct kvm_vcpu *vcpu,
vcpu->arch.mp_state == KVM_MP_STATE_INIT_RECEIVED)
return -EINVAL;
+ if (events->exception.injected) {
+ bool has_error_code = is_protmode(vcpu) &&
+ x86_exception_has_error_code(events->exception.nr);
+
+ if (!!events->exception.has_error_code != has_error_code)
+ return -EINVAL;
+ }
+
process_nmi(vcpu);
vcpu->arch.exception.injected = false;
vcpu->arch.exception.pending = events->exception.injected;
@@ -8170,6 +8178,14 @@ static int kvm_valid_sregs(struct kvm_vcpu *vcpu, struct kvm_sregs *sregs)
return -EINVAL;
}
+ if (vcpu->arch.exception.injected || vcpu->arch.exception.pending) {
+ bool has_error_code = (sregs->cr0 & X86_CR0_PE) &&
+ x86_exception_has_error_code(vcpu->arch.exception.nr);
+
+ if (vcpu->arch.exception.has_error_code != has_error_code)
+ return -EINVAL;
+ }
+
return 0;
}
--
2.19.1.331.ge82ca0e54c-goog
