KVM: x86: verify MTRR/PAT validity

[Marcelo Tosatti <mtosatti@redhat.com>]

Do not allow invalid MTRR/PAT values in set_msr_mtrr.

Please review carefully.

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


Index: kvm/arch/x86/kvm/x86.c
===================================================================
--- kvm.orig/arch/x86/kvm/x86.c
+++ kvm/arch/x86/kvm/x86.c
@@ -722,11 +722,53 @@ static bool msr_mtrr_valid(unsigned msr)
 	return false;
 }
 
+static unsigned mtrr_types[] = {0, 1, 4, 5, 6};
+static unsigned pat_types[] = {0, 1, 4, 5, 6, 7};
+
+static bool valid_mt(unsigned type, int len, unsigned array[len])
+{
+	int i;
+
+	for (i = 0; i < len; i++)
+		if (type == array[i])
+			return true;
+
+	return false;
+}
+
+#define valid_pat_type(a) valid_mt(a, ARRAY_SIZE(pat_types), pat_types)
+#define valid_mtrr_type(a) valid_mt(a, ARRAY_SIZE(mtrr_types), mtrr_types)
+
+static bool mtrr_valid(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) {
+		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, physmaskn have bits 0-10 reserved */
+	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(msr, data))
 		return 1;
 
 	if (msr == MSR_MTRRdefType) {