KVM: x86: verify MTRR/PAT validity

Do not allow invalid memory types in MTRR/PAT (generating a #GP
otherwise).

Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>
Signed-off-by: Avi Kivity <avi@redhat.com>

1 files changed, 38 insertions, 1 deletions

diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index 7bc311464fae..3d4529011828 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -704,11 +704,48 @@ static bool msr_mtrr_valid(unsigned msr)
         return false;
 }
 
+static bool valid_pat_type(unsigned t)
+{
+        return t < 8 && (1 << t) & 0xf3; /* 0, 1, 4, 5, 6, 7 */
+}
+
+static bool valid_mtrr_type(unsigned t)
+{
+        return t < 8 && (1 << t) & 0x73; /* 0, 1, 4, 5, 6 */
+}
+
+static bool mtrr_valid(struct kvm_vcpu *vcpu, u32 msr, u64 data)
+{
+        int i;
+
+        if (!msr_mtrr_valid(msr))
+                return false;
+
+        if (msr == MSR_IA32_CR_PAT) {
+                for (i = 0; i < 8; i++)
+                        if (!valid_pat_type((data >> (i * 8)) & 0xff))
+                                return false;
+                return true;
+        } else if (msr == MSR_MTRRdefType) {
+                if (data & ~0xcff)
+                        return false;
+                return valid_mtrr_type(data & 0xff);
+        } else if (msr >= MSR_MTRRfix64K_00000 && msr <= MSR_MTRRfix4K_F8000) {
+                for (i = 0; i < 8 ; i++)
+                        if (!valid_mtrr_type((data >> (i * 8)) & 0xff))
+                                return false;
+                return true;
+        }
+
+        /* variable MTRRs */
+        return valid_mtrr_type(data & 0xff);
+}
+
 static int set_msr_mtrr(struct kvm_vcpu *vcpu, u32 msr, u64 data)
 {
         u64 *p = (u64 *)&vcpu->arch.mtrr_state.fixed_ranges;
 
-        if (!msr_mtrr_valid(msr))
+        if (!mtrr_valid(vcpu, msr, data))
                 return 1;
 
         if (msr == MSR_MTRRdefType) {