On 1/24/22 11:36, Vitaly Kuznetsov wrote:
kvm_cpuid_check_equal() should also check .flags equality but instead
of adding it to the existing check, just switch to using memcmp() for
the whole 'struct kvm_cpuid_entry2'.
When .flags are not checked, kvm_cpuid_check_equal() may allow an update
which it shouldn't but kvm_set_cpuid() does not actually update anything
and just returns success.
Suggested-by: Sean Christopherson <seanjc@xxxxxxxxxx>
Signed-off-by: Vitaly Kuznetsov <vkuznets@xxxxxxxxxx>
---
arch/x86/kvm/cpuid.c | 13 ++-----------
1 file changed, 2 insertions(+), 11 deletions(-)
diff --git a/arch/x86/kvm/cpuid.c b/arch/x86/kvm/cpuid.c
index 89d7822a8f5b..7dd9c8f4f46e 100644
--- a/arch/x86/kvm/cpuid.c
+++ b/arch/x86/kvm/cpuid.c
@@ -123,20 +123,11 @@ static int kvm_check_cpuid(struct kvm_vcpu *vcpu,
static int kvm_cpuid_check_equal(struct kvm_vcpu *vcpu, struct kvm_cpuid_entry2 *e2,
int nent)
{
- struct kvm_cpuid_entry2 *orig;
- int i;
-
if (nent != vcpu->arch.cpuid_nent)
return -EINVAL;
- for (i = 0; i < nent; i++) {
- orig = &vcpu->arch.cpuid_entries[i];
- if (e2[i].function != orig->function ||
- e2[i].index != orig->index ||
- e2[i].eax != orig->eax || e2[i].ebx != orig->ebx ||
- e2[i].ecx != orig->ecx || e2[i].edx != orig->edx)
- return -EINVAL;
- }
+ if (memcmp(e2, vcpu->arch.cpuid_entries, nent * sizeof(*e2)))
+ return -EINVAL;
Hmm, not sure about that due to the padding in struct kvm_cpuid_entry2.
It might break userspace that isn't too careful about zeroing it.
Queued patch 1 though.
Paolo
