From: Jim Mattson <jmattson@xxxxxxxxxx>
commit 85c856b39b479dde410ddd09df1da745343010c9 upstream
Bitwise shifts by amounts greater than or equal to the width of the left
operand are undefined. A malicious guest can exploit this to crash a
32-bit host, due to the BUG_ON(1)'s in handle_{invept,invvpid}.
Signed-off-by: Jim Mattson <jmattson@xxxxxxxxxx>
Message-Id: <1477496318-17681-1-git-send-email-jmattson@xxxxxxxxxx>
[Change 1UL to 1, to match the range check on the shift count. - Paolo]
Signed-off-by: Paolo Bonzini <pbonzini@xxxxxxxxxx>
[jwang: port from linux-4.9 to 4.4 ]
Signed-off-by: Jack Wang <jinpu.wang@xxxxxxxxxxxxxxxx>
---
arch/x86/kvm/vmx.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)
diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c
index 6c753b9..43c2996 100644
--- a/arch/x86/kvm/vmx.c
+++ b/arch/x86/kvm/vmx.c
@@ -7361,7 +7361,7 @@ static int handle_invept(struct kvm_vcpu *vcpu)
types = (vmx->nested.nested_vmx_ept_caps >> VMX_EPT_EXTENT_SHIFT) & 6;
- if (!(types & (1UL << type))) {
+ if (type >= 32 || !(types & (1 << type))) {
nested_vmx_failValid(vcpu,
VMXERR_INVALID_OPERAND_TO_INVEPT_INVVPID);
skip_emulated_instruction(vcpu);
@@ -7420,7 +7420,7 @@ static int handle_invvpid(struct kvm_vcpu *vcpu)
types = (vmx->nested.nested_vmx_vpid_caps >> 8) & 0x7;
- if (!(types & (1UL << type))) {
+ if (type >= 32 || !(types & (1 << type))) {
nested_vmx_failValid(vcpu,
VMXERR_INVALID_OPERAND_TO_INVEPT_INVVPID);
skip_emulated_instruction(vcpu);
--
2.7.4