dict: Put "goto out" in dict_unserialize to avoid process crash

Problem:
In the dictionary serialization function, if the
[(buf + vallen) > (orig_buf + size)], then memdup is getting failed.

Fix:
Put "goto out" whenever this condition is met.

Change-Id: I662628a936596dbb47825aad47d7dbab2879eb07
BUG: 947824
Signed-off-by: Venkatesh Somyajulu <vsomyaju@redhat.com>
Reviewed-on: http://review.gluster.org/4767
Tested-by: Gluster Build System <jenkins@build.gluster.com>
Reviewed-by: Anand Avati <avati@redhat.com>

libglusterfs/src/dict.c

@@ -2576,6 +2576,7 @@ dict_unserialize (char *orig_buf, int32_t size, dict_t **fill)
                                           "available (%lu) < required (%lu)",
                                           (long)(orig_buf + size),
                                           (long)(buf + vallen));
+                        goto out;
                 }
                 value = get_new_data ();
                 value->len  = vallen;