BZ #15754: CVE-2013-4788

The pointer guard used for pointer mangling was not initialized for
static applications resulting in the security feature being disabled.
The pointer guard is now correctly initialized to a random value for
static applications. Existing static applications need to be
recompiled to take advantage of the fix.

The test tst-ptrguard1-static and tst-ptrguard1 add regression
coverage to ensure the pointer guards are sufficiently random
and initialized to a default value.

sysdeps/x86_64/stackguard-macros.h

@@ -4,3 +4,8 @@
   ({ uintptr_t x;						\
      asm ("mov %%fs:%c1, %0" : "=r" (x)				\
 	  : "i" (offsetof (tcbhead_t, stack_guard))); x; })
+
+#define POINTER_CHK_GUARD \
+  ({ uintptr_t x;						\
+     asm ("mov %%fs:%c1, %0" : "=r" (x)				\
+	  : "i" (offsetof (tcbhead_t, pointer_guard))); x; })