Check for out-of-bound accesses in the CoT description

The chain of trust array is now always accessed through a fconf getter.
This gives us an ideal spot to check for out-of-bound accesses.

Change-Id: Ic5ea20e43cf8ca959bb7f9b60de7c0839b390add
Signed-off-by: Sandrine Bailleux <sandrine.bailleux@arm.com>
diff --git a/include/lib/fconf/fconf_tbbr_getter.h b/include/lib/fconf/fconf_tbbr_getter.h
index eddc0c4..db98b68 100644
--- a/include/lib/fconf/fconf_tbbr_getter.h
+++ b/include/lib/fconf/fconf_tbbr_getter.h
@@ -7,10 +7,15 @@
 #ifndef FCONF_TBBR_GETTER_H
 #define FCONF_TBBR_GETTER_H
 
+#include <assert.h>
+
 #include <lib/fconf/fconf.h>
 
 /* TBBR related getter */
-#define tbbr__cot_getter(id)	cot_desc_ptr[id]
+#define tbbr__cot_getter(id) __extension__ ({	\
+	assert((id) < cot_desc_size);		\
+	cot_desc_ptr[id];			\
+})
 
 #define tbbr__dyn_config_getter(id)	tbbr_dyn_config.id