Fix zlib CVE-2016-9842.

1 files changed, 3 insertions, 2 deletions

diff --git a/zlib/inflate.c b/zlib/inflate.c
index 5ed2390d..e43abd9e 100644
--- a/zlib/inflate.c
+++ b/zlib/inflate.c
@@ -1526,9 +1526,10 @@ 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));
 }