From 38dbe53737d82af58104a15ac69fdfe19eef5bdc Mon Sep 17 00:00:00 2001 From: Sean Christopherson Date: Mon, 24 May 2021 12:05:30 +0000 Subject: [PATCH] KVM: nVMX: Truncate bits 63:32 of VMCS field on nested check in !64-bit stable inclusion from stable-5.10.37 commit 6b7028de661da0a2e687ff80cf999ae3a55b385f bugzilla: 51868 CVE: NA -------------------------------- commit ee050a577523dfd5fac95e6cc182ebe0293ead59 upstream. Drop bits 63:32 of the VMCS field encoding when checking for a nested VM-Exit on VMREAD/VMWRITE in !64-bit mode. VMREAD and VMWRITE always use 32-bit operands outside of 64-bit mode. The actual emulation of VMREAD/VMWRITE does the right thing, this bug is purely limited to incorrectly causing a nested VM-Exit if a GPR happens to have bits 63:32 set outside of 64-bit mode. Fixes: a7cde481b6e8 ("KVM: nVMX: Do not forward VMREAD/VMWRITE VMExits to L1 if required so by vmcs12 vmread/vmwrite bitmaps") Cc: stable@vger.kernel.org Signed-off-by: Sean Christopherson Message-Id: <20210422022128.3464144-6-seanjc@google.com> Signed-off-by: Paolo Bonzini Signed-off-by: Greg Kroah-Hartman Signed-off-by: Chen Jun Acked-by: Weilong Chen Signed-off-by: Zheng Zengkai --- arch/x86/kvm/vmx/nested.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/arch/x86/kvm/vmx/nested.c b/arch/x86/kvm/vmx/nested.c index bce4f0cd9511..e57f57f792de 100644 --- a/arch/x86/kvm/vmx/nested.c +++ b/arch/x86/kvm/vmx/nested.c @@ -5724,7 +5724,7 @@ static bool nested_vmx_exit_handled_vmcs_access(struct kvm_vcpu *vcpu, /* Decode instruction info and find the field to access */ vmx_instruction_info = vmcs_read32(VMX_INSTRUCTION_INFO); - field = kvm_register_read(vcpu, (((vmx_instruction_info) >> 28) & 0xf)); + field = kvm_register_readl(vcpu, (((vmx_instruction_info) >> 28) & 0xf)); /* Out-of-range fields always cause a VM exit from L2 to L1 */ if (field >> 15) -- GitLab