From: Paolo Bonzini <pbonzini@redhat.com>
Date: Fri, 24 Oct 2014 17:07:21 +0200
Subject: [PATCH] KVM: emulate: avoid accessing NULL ctxt->memopp
 
A failure to decode the instruction can cause a NULL pointer access.
This is fixed simply by moving the "done" label as close as possible
to the return.
 
This fixes CVE-2014-8481.
 
Reported-by: Andy Lutomirski <luto@amacapital.net>
Cc: stable@vger.kernel.org
Fixes: 41061cdb98a0bec464278b4db8e894a3121671f5
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
---
 arch/x86/kvm/emulate.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)
 
diff --git a/arch/x86/kvm/emulate.c b/arch/x86/kvm/emulate.c
index a0a04090d2ff..5669ed12f9ee 100644
--- a/arch/x86/kvm/emulate.c
+++ b/arch/x86/kvm/emulate.c
@@ -4565,10 +4565,10 @@ done_prefixes:
 	/* Decode and fetch the destination operand: register or memory. */
 	rc = decode_operand(ctxt, &ctxt->dst, (ctxt->d >> DstShift) & OpMask);
 
-done:
 	if (ctxt->rip_relative)
 		ctxt->memopp->addr.mem.ea += ctxt->_eip;
 
+done:
 	return (rc != X86EMUL_CONTINUE) ? EMULATION_FAILED : EMULATION_OK;
 }
 
-- 
1.9.3