KVM: x86: work around leak of uninitialized stack contents (CVE-2019-7222)

[uclinux-h8/linux.git] / arch / x86 / kvm / x86.c

diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index 3d27206..e67ecf2 100644 (file)
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -5116,6 +5116,13 @@ int kvm_read_guest_virt(struct kvm_vcpu *vcpu,
 {
        u32 access = (kvm_x86_ops->get_cpl(vcpu) == 3) ? PFERR_USER_MASK : 0;
 
+       /*
+        * FIXME: this should call handle_emulation_failure if X86EMUL_IO_NEEDED
+        * is returned, but our callers are not ready for that and they blindly
+        * call kvm_inject_page_fault.  Ensure that they at least do not leak
+        * uninitialized kernel stack memory into cr2 and error code.
+        */
+       memset(exception, 0, sizeof(*exception));
        return kvm_read_guest_virt_helper(addr, val, bytes, vcpu, access,
                                          exception);
 }