From e54e1299404101a5a9d0cf5e45512b543967f958 Mon Sep 17 00:00:00 2001
From: Mark Adler <madler@alumni.caltech.edu>
Date: Sat, 5 Sep 2015 17:45:55 -0700
Subject: [PATCH] Avoid shifts of negative values inflateMark().

The C standard says that bit shifts of negative integers is
undefined.  This casts to unsigned values to assure a known
result.

CVE: CVE-2016-9842
Upstream-Status: Backport
Signed-off-by: Anuj Mittal <anuj.mittal@intel.com>
---
 inflate.c | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/zlib/inflate.c b/zlib/inflate.c
index 2889e3a0..a7184167 100644
--- a/zlib/inflate.c
+++ b/zlib/inflate.c
@@ -1506,9 +1506,10 @@ z_streamp strm;
 {
     struct inflate_state FAR *state;
 
-    if (strm == Z_NULL || strm->state == Z_NULL) return -1L << 16;
+    if (strm == Z_NULL || strm->state == Z_NULL)
+        return (long)(((unsigned long)0 - 1) << 16);
     state = (struct inflate_state FAR *)strm->state;
-    return ((long)(state->back) << 16) +
+    return (long)(((unsigned long)((long)state->back)) << 16) +
         (state->mode == COPY ? state->length :
             (state->mode == MATCH ? state->was - state->length : 0));
 }
