KVM: x86: Assertions to check no overrun in MSR lists

Currently there is no check whether shared MSRs list overrun the allocated size
which can results in bugs. In addition there is no check that vmx->guest_msrs
has sufficient space to accommodate all the VMX msrs.  This patch adds the
assertions.

Signed-off-by: Nadav Amit <namit@cs.technion.ac.il>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c
index fd24f68378a7d06c6d880111c113c12b9dfb6a69..3397a88b746336539947d617eed6aa212ead2550 100644 (file)
--- a/arch/x86/kvm/vmx.c
+++ b/arch/x86/kvm/vmx.c
@@ -7608,6 +7608,8 @@ static struct kvm_vcpu *vmx_create_vcpu(struct kvm *kvm, unsigned int id)
                goto free_vcpu;
 
        vmx->guest_msrs = kmalloc(PAGE_SIZE, GFP_KERNEL);
+       BUILD_BUG_ON(PAGE_SIZE / sizeof(struct shared_msr_entry) < NR_VMX_MSR);
+
        err = -ENOMEM;
        if (!vmx->guest_msrs) {
                goto uninit_vcpu;

diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index 439f96bf424df5018d252a65bece9a8e0f07d7f7..d38abc81db65063b9842afc1bb2be3616c5d39bc 100644 (file)
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -212,6 +212,7 @@ static void shared_msr_update(unsigned slot, u32 msr)
 
 void kvm_define_shared_msr(unsigned slot, u32 msr)
 {
+       BUG_ON(slot >= KVM_NR_SHARED_MSRS);
        if (slot >= shared_msrs_global.nr)
                shared_msrs_global.nr = slot + 1;
        shared_msrs_global.msrs[slot] = msr;