Original patch from: gentoo/src/patchsets/glibc/2.9/0053_all_glibc-2.9-regex-BZ697.patch

-= BEGIN original header =-
http://sourceware.org/ml/libc-alpha/2009-01/msg00006.html

From 37bdc055ceeb6b1144c07448a7210d9ab3fbb2f5 Mon Sep 17 00:00:00 2001
From: Ulrich Drepper <drepper@redhat.com>
Date: Thu, 8 Jan 2009 00:47:05 +0000
Subject: [PATCH] (prune_impossible_nodes): Handle sifted_states[0] being NULL also if
 there are no backreferences.

-= END original header =-

diff -durN glibc-2_9.orig/posix/regexec.c glibc-2_9/posix/regexec.c
--- glibc-2_9.orig/posix/regexec.c	2007-10-12 19:47:13.000000000 +0200
+++ glibc-2_9/posix/regexec.c	2009-02-02 22:00:43.000000000 +0100
@@ -1004,6 +1004,11 @@
       re_node_set_free (&sctx.limits);
       if (BE (ret != REG_NOERROR, 0))
 	goto free_return;
+      if (sifted_states[0] == NULL)
+	{
+	  ret = REG_NOMATCH;
+	  goto free_return;
+	}
     }
   re_free (mctx->state_log);
   mctx->state_log = sifted_states;
