Add memory poisoning framework

While an area of memory is poisoned, reading or writing from it triggers a
sanitizer violation.

Implemented for ASan.

Signed-off-by: Gilles Peskine <Gilles.Peskine@arm.com>

tests/include/test/memory.h

@@ -15,4 +15,79 @@
 #include "mbedtls/build_info.h"
 #include "mbedtls/platform.h"
 
+/** \def MBEDTLS_TEST_MEMORY_CAN_POISON
+ *
+ * This macro is defined if the tests are compiled with a method to mark
+ * memory as poisoned, which can be used to enforce some memory access
+ * policies.
+ *
+ * Currently, only Asan (Address Sanitizer) is supported.
+ */
+#if defined(__SANITIZE_ADDRESS__)
+#  define MBEDTLS_TEST_HAVE_ASAN
+#endif
+#if defined(__has_feature)
+#  if __has_feature(address_sanitizer)
+#    define MBEDTLS_TEST_HAVE_ASAN
+#  endif
+#endif
+#if defined(MBEDTLS_TEST_HAVE_ASAN)
+#  define MBEDTLS_TEST_MEMORY_CAN_POISON
+#endif
+
+/** \def MBEDTLS_TEST_MEMORY_POISON(buf, size)
+ *
+ * Poison a memory area so that any attempt to read or write from it will
+ * cause a runtime failure.
+ *
+ * The behavior is undefined if any part of the memory area is invalid.
+ *
+ * This is a no-op in builds without a poisoning method.
+ * See #MBEDTLS_TEST_MEMORY_CAN_POISON.
+ *
+ * \param buf   Pointer to the beginning of the memory area to poison.
+ * \param size  Size of the memory area in bytes.
+ */
+
+/** \def MBEDTLS_TEST_MEMORY_UNPOISON(buf, size)
+ *
+ * Undo the effect of #MBEDTLS_TEST_MEMORY_POISON.
+ *
+ * The behavior is undefined if any part of the memory area is invalid,
+ * or if the memory area contains a mixture of poisoned and unpoisoned parts.
+ *
+ * This is a no-op in builds without a poisoning method.
+ * See #MBEDTLS_TEST_MEMORY_CAN_POISON.
+ *
+ * \param buf   Pointer to the beginning of the memory area to unpoison.
+ * \param size  Size of the memory area in bytes.
+ */
+
+#if defined(MBEDTLS_TEST_MEMORY_CAN_POISON)
+
+/** Poison a memory area so that any attempt to read or write from it will
+ * cause a runtime failure.
+ *
+ * The behavior is undefined if any part of the memory area is invalid.
+ */
+void mbedtls_test_memory_poison(const unsigned char *ptr, size_t size);
+#define MBEDTLS_TEST_MEMORY_POISON(ptr, size)    \
+    mbedtls_test_memory_poison(ptr, size)
+
+/** Undo the effect of mbedtls_test_memory_poison().
+ *
+ * This is a no-op if the given area is entirely valid, unpoisoned memory.
+ *
+ * The behavior is undefined if any part of the memory area is invalid,
+ * or if the memory area contains a mixture of poisoned and unpoisoned parts.
+ */
+void mbedtls_test_memory_unpoison(const unsigned char *ptr, size_t size);
+#define MBEDTLS_TEST_MEMORY_UNPOISON(ptr, size)    \
+    mbedtls_test_memory_unpoison(ptr, size)
+
+#else /* MBEDTLS_TEST_MEMORY_CAN_POISON */
+#define MBEDTLS_TEST_MEMORY_POISON(ptr, size) ((void) 0)
+#define MBEDTLS_TEST_MEMORY_UNPOISON(ptr, size) ((void) 0)
+#endif /* MBEDTLS_TEST_MEMORY_CAN_POISON */
+
 #endif /* TEST_MEMORY_H */