Fix for CVE-2013-4788 from http://hmarco.org/bugs/CVE-2013-4788.html

Signed-off-by: Gustavo Zacarias <gustavo@zacarias.com.ar>

diff -rupN glibc-2.17/csu/libc-start.c glibc-2.17-mangle-fix/csu/libc-start.c
--- glibc-2.17/libc/csu/libc-start.c	2012-12-25 04:02:13.000000000 +0100
+++ glibc-2.17-mangle-fix/libc/csu/libc-start.c	2013-07-10 00:13:48.000000000 +0200
@@ -38,6 +38,12 @@ extern void __pthread_initialize_minimal
    in thread local area.  */
 uintptr_t __stack_chk_guard attribute_relro;
 # endif
+
+# ifndef  THREAD_SET_POINTER_GUARD
+uintptr_t __pointer_chk_guard_local
+     attribute_relro attribute_hidden __attribute__ ((nocommon));
+# endif
+
 #endif
 
 #ifdef HAVE_PTR_NTHREADS
@@ -184,6 +190,14 @@ LIBC_START_MAIN (int (*main) (int, char
 # else
   __stack_chk_guard = stack_chk_guard;
 # endif
+    uintptr_t pointer_chk_guard = _dl_setup_pointer_guard (_dl_random,
+                          stack_chk_guard);
+# ifdef THREAD_SET_POINTER_GUARD
+      THREAD_SET_POINTER_GUARD (pointer_chk_guard);
+# else
+      __pointer_chk_guard_local = pointer_chk_guard;
+# endif
+
 #endif
 
   /* Register the destructor of the dynamic linker if there is any.  */
