[PATCH 3.2 037/106] KVM: x86: zero base3 of unusable segments

[Ben Hutchings]

3.2.93-rc1 review patch.  If anyone has any objections, please let me know.

------------------

From: Radim Krčmář <rkrc...@redhat.com>

commit f0367ee1d64d27fa08be2407df5c125442e885e3 upstream.

Static checker noticed that base3 could be used uninitialized if the
segment was not present (useable).  Random stack values probably would
not pass VMCS entry checks.

Reported-by:  Dan Carpenter <dan.carpen...@oracle.com>
Fixes: 1aa366163b8b ("KVM: x86 emulator: consolidate segment accessors")
Reviewed-by: Paolo Bonzini <pbonz...@redhat.com>
Reviewed-by: David Hildenbrand <da...@redhat.com>
Signed-off-by: Radim Krčmář <rkrc...@redhat.com>
Signed-off-by: Ben Hutchings <b...@decadent.org.uk>
---
 arch/x86/kvm/x86.c | 2 ++
 1 file changed, 2 insertions(+)

--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -4613,6 +4613,8 @@ static bool emulator_get_segment(struct
 
        if (var.unusable) {
                memset(desc, 0, sizeof(*desc));
+               if (base3)
+                       *base3 = 0;
                return false;
        }