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authorZhenzhong Duan <zhenzhong.duan@intel.com>2021-09-26 09:55:45 +0800
committerPaolo Bonzini <pbonzini@redhat.com>2021-09-27 11:25:40 -0400
commit5c49d1850ddd3240d20dc40b01f593e35a184f38 (patch)
tree3731e09e04ed668099b922a49f8ab78529d0f949 /arch
parent50b078184604fea95adbb144ff653912fb0e48c6 (diff)
KVM: VMX: Fix a TSX_CTRL_CPUID_CLEAR field mask issue
When updating the host's mask for its MSR_IA32_TSX_CTRL user return entry, clear the mask in the found uret MSR instead of vmx->guest_uret_msrs[i]. Modifying guest_uret_msrs directly is completely broken as 'i' does not point at the MSR_IA32_TSX_CTRL entry. In fact, it's guaranteed to be an out-of-bounds accesses as is always set to kvm_nr_uret_msrs in a prior loop. By sheer dumb luck, the fallout is limited to "only" failing to preserve the host's TSX_CTRL_CPUID_CLEAR. The out-of-bounds access is benign as it's guaranteed to clear a bit in a guest MSR value, which are always zero at vCPU creation on both x86-64 and i386. Cc: stable@vger.kernel.org Fixes: 8ea8b8d6f869 ("KVM: VMX: Use common x86's uret MSR list as the one true list") Signed-off-by: Zhenzhong Duan <zhenzhong.duan@intel.com> Reviewed-by: Sean Christopherson <seanjc@google.com> Message-Id: <20210926015545.281083-1-zhenzhong.duan@intel.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Diffstat (limited to 'arch')
-rw-r--r--arch/x86/kvm/vmx/vmx.c2
1 files changed, 1 insertions, 1 deletions
diff --git a/arch/x86/kvm/vmx/vmx.c b/arch/x86/kvm/vmx/vmx.c
index 9ecfcf13a046..116b08904ac3 100644
--- a/arch/x86/kvm/vmx/vmx.c
+++ b/arch/x86/kvm/vmx/vmx.c
@@ -6848,7 +6848,7 @@ static int vmx_create_vcpu(struct kvm_vcpu *vcpu)
*/
tsx_ctrl = vmx_find_uret_msr(vmx, MSR_IA32_TSX_CTRL);
if (tsx_ctrl)
- vmx->guest_uret_msrs[i].mask = ~(u64)TSX_CTRL_CPUID_CLEAR;
+ tsx_ctrl->mask = ~(u64)TSX_CTRL_CPUID_CLEAR;
}
err = alloc_loaded_vmcs(&vmx->vmcs01);

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