From: Jan Beulich <jbeulich@suse.com>
Date: Mon, 13 Feb 2017 14:20:55 +0000 (+0100)
Subject: x86emul: always init mmval
X-Git-Tag: archive/raspbian/4.11.1-1+rpi1~1^2~66^2~2805
X-Git-Url: https://dgit.raspbian.org/?a=commitdiff_plain;h=b857b041ee73d24fefa2dce55d23e2ff97306af2;p=xen.git

x86emul: always init mmval

... to avoid buggy read/write sizes becoming info leaks.

Signed-off-by: Jan Beulich <jbeulich@suse.com>
Reviewed-by: Andrew Cooper <andrew.cooper3@citrix.com>
---

diff --git a/xen/arch/x86/x86_emulate/x86_emulate.c b/xen/arch/x86/x86_emulate/x86_emulate.c
index 270b5c6441..6cd9487291 100644
--- a/xen/arch/x86/x86_emulate/x86_emulate.c
+++ b/xen/arch/x86/x86_emulate/x86_emulate.c
@@ -2671,6 +2671,8 @@ x86_emulate(
         ea.reg = decode_register(modrm_rm, &_regs,
                                  (d & ByteOp) && !rex_prefix);
 
+    memset(mmvalp, 0xaa /* arbitrary */, sizeof(*mmvalp));
+
     /* Decode and fetch the source operand: register, memory or immediate. */
     switch ( d & SrcMask )
     {