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/i386/stackguard-macros.h

@@ -2,3 +2,11 @@
 
 #define STACK_CHK_GUARD \
   ({ uintptr_t x; asm ("movl %%gs:0x14, %0" : "=r" (x)); x; })
+
+#define POINTER_CHK_GUARD \
+  ({							\
+     uintptr_t x;					\
+     asm ("movl %%gs:%c1, %0" : "=r" (x)		\
+	  : "i" (offsetof (tcbhead_t, pointer_guard)));	\
+     x;							\
+   })