kvm: nVMX: Fix kernel panics induced by illegal INVEPT/INVVPID types

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@google.com>
Message-Id: <1477496318-17681-1-git-send-email-jmattson@google.com>
[Change 1UL to 1, to match the range check on the shift count. - Paolo]
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
[jwang: port from linux-4.9 to 4.4 ]
Signed-off-by: Jack Wang <jinpu.wang@profitbricks.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c
index 6c753b966c280b72c54ad28ef301c5a4a2ed5e5d..43c2996c1f73522b3b2b4411143551b3a6395d7b 100644 (file)
--- 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);