commit 967714d8e77c00c08f061243a6fc2aa526e93c36
author Gilles Peskine <Gilles.Peskine@arm.com> Thu Nov 02 19:52:32 2023 +0100
committer Gilles Peskine <Gilles.Peskine@arm.com> Thu Nov 16 15:56:23 2023 +0100
tree 2a27fa88961a92272e9cb0f33a0af7d79de812d8
parent 970584f32fef06f3b2c88c439ba3665f646fdd1e

Strengthen against Clang optimizations

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

programs/test/metatest.c

diff --git a/programs/test/metatest.c b/programs/test/metatest.c
index 91a1e2a..eb3bb76 100644
--- a/programs/test/metatest.c
+++ b/programs/test/metatest.c
@@ -11,12 +11,21 @@
 #define MBEDTLS_ALLOW_PRIVATE_ACCESS
 
 #include <mbedtls/platform.h>
+#include <mbedtls/platform_util.h>
 #include "test/helpers.h"
 
 #include <stdio.h>
 #include <string.h>
 
 
+/* This is an external variable, so the compiler doesn't know that we're never
+ * changing its value.
+ *
+ * TODO: LTO (link-time-optimization) would defeat this.
+ */
+int false_but_the_compiler_does_not_know = 0;
+
+
 /****************************************************************/
 /* Test framework features */
 /****************************************************************/
@@ -35,19 +44,17 @@
 void null_pointer_dereference(const char *name)
 {
     (void) name;
-    char *p;
-    memset(&p, 0, sizeof(p));
-    volatile char c;
-    c = *p;
-    (void) c;
+    volatile char *p;
+    mbedtls_platform_zeroize(&p, sizeof(p));
+    mbedtls_printf("%p -> %u\n", p, (unsigned) *p);
 }
 
 void null_pointer_call(const char *name)
 {
     (void) name;
-    void (*p)(void);
-    memset(&p, 0, sizeof(p));
-    p();
+    unsigned (*p)(void);
+    mbedtls_platform_zeroize(&p, sizeof(p));
+    mbedtls_printf("%p() -> %u\n", p, p());
 }
 
 
@@ -77,7 +84,6 @@
 {
     (void) name;
     volatile char buf[1];
-    static int false_but_the_compiler_does_not_know = 0;
     if (false_but_the_compiler_does_not_know) {
         buf[0] = '!';
     }