2014-07-13  Jim Meyering  <meyering@fb.com>

	[BZ 17150]
	regex: don't deref NULL upon heap allocation failure
	* posix/regcomp.c: (parse_dup_op): Handle duplicate_tree
	failure in one more place.
	To trigger the segfault, configure grep -with-included-regex,
	build it, and run these commands:
	( ulimit -v 300000; echo a|src/grep -E a+++++++++++++++++++++ )

--- a/posix/regcomp.c
+++ b/posix/regcomp.c
@@ -2582,6 +2582,8 @@ parse_dup_op (bin_tree_t *elem, re_string_t *regexp, re_dfa_t *dfa,
 
       /* Duplicate ELEM before it is marked optional.  */
       elem = duplicate_tree (elem, dfa);
+      if (BE (elem == NULL, 0))
+        goto parse_dup_op_espace;
       old_tree = tree;
     }
   else