From 77d977dd78b36385e5c284095ce28b3a6b8fe6fb Mon Sep 17 00:00:00 2001
From: =?utf8?q?Radim=20Kr=C4=8Dm=C3=A1=C5=99?= <rkrcmar@redhat.com>
Date: Thu, 18 May 2017 19:37:30 +0200
Subject: [PATCH] KVM: x86: zero base3 of unusable segments
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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.carpenter@oracle.com>
Fixes: 1aa366163b8b ("KVM: x86 emulator: consolidate segment accessors")
Reviewed-by: Paolo Bonzini <pbonzini@redhat.com>
Reviewed-by: David Hildenbrand <david@redhat.com>
Signed-off-by: Radim Krčmář <rkrcmar@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
 arch/x86/kvm/x86.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index 88f914ea2db7..8e526c6fd784 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -4844,6 +4844,8 @@ static bool emulator_get_segment(struct x86_emulate_ctxt *ctxt, u16 *selector,
 
 	if (var.unusable) {
 		memset(desc, 0, sizeof(*desc));
+		if (base3)
+			*base3 = 0;
 		return false;
 	}
 
-- 
2.34.1