KVM: x86: work around leak of uninitialized stack contents

[android-x86/kernel.git] / arch / x86 / kvm / x86.c

diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index 290c3c3..91602d3 100644 (file)
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -5312,6 +5312,13 @@ int kvm_write_guest_virt_system(struct kvm_vcpu *vcpu, gva_t addr, void *val,
        /* kvm_write_guest_virt_system can pull in tons of pages. */
        vcpu->arch.l1tf_flush_l1d = true;
 
+       /*
+        * 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_write_guest_virt_helper(addr, val, bytes, vcpu,
                                           PFERR_WRITE_MASK, exception);
 }