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;