[PATCH 4.4 23/45] kvm: fix page struct leak in handle_vmon

Greg Kroah-Hartman
2017-04-19T15:04:43Z

From: Paolo Bonzini <pbonzini@redhat.com>

commit 06ce521af9558814b8606c0476c54497cf83a653 upstream.

handle_vmon gets a reference on VMXON region page,
but does not release it. Release the reference.

Found by syzkaller; based on a patch by Dmitry.

Reported-by: Dmitry Vyukov <dvyukov@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
[bwh: Backported to 3.16: use skip_emulated_instruction()]
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
arch/x86/kvm/vmx.c | 10 ++++++++--
1 file changed, 8 insertions(+), 2 deletions(-)

--- a/arch/x86/kvm/vmx.c
+++ b/arch/x86/kvm/vmx.c
@@ -6678,14 +6678,20 @@ static int nested_vmx_check_vmptr(struct
}

page = nested_get_page(vcpu, vmptr);
- if (page == NULL ||
- *(u32 *)kmap(page) != VMCS12_REVISION) {
+ if (page == NULL) {
nested_vmx_failInvalid(vcpu);
+ skip_emulated_instruction(vcpu);
+ return 1;
+ }
+ if (*(u32 *)kmap(page) != VMCS12_REVISION) {
kunmap(page);
+ nested_release_page_clean(page);
+ nested_vmx_failInvalid(vcpu);
skip_emulated_instruction(vcpu);
return 1;
}
kunmap(page);
+ nested_release_page_clean(page);
vmx->nested.vmxon_ptr = vmptr;
break;