Merge pull request #7386 from daverodgman/timing_alignment-2.28

Backport 2.28 - Timing alignment
Mbed-TLS · Mar 31, 2023 · 83faeca · 83faeca
2 parents 616f23e + 2497c6b
commit 83faeca
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Showing 2 changed files with 27 additions and 7 deletions.
diff --git a/library/timing.c b/library/timing.c
@@ -17,6 +17,8 @@
  *  limitations under the License.
  */
 
+#include <string.h>
+
 #include "common.h"
 
 #include "mbedtls/platform.h"
@@ -231,17 +233,20 @@ volatile int mbedtls_timing_alarmed = 0;
 
 unsigned long mbedtls_timing_get_timer(struct mbedtls_timing_hr_time *val, int reset)
 {
-    struct _hr_time *t = (struct _hr_time *) val;
+    struct _hr_time t;
 
     if (reset) {
-        QueryPerformanceCounter(&t->start);
+        QueryPerformanceCounter(&t.start);
+        memcpy(val, &t, sizeof(struct _hr_time));
         return 0;
     } else {
         unsigned long delta;
         LARGE_INTEGER now, hfreq;
+        /* We can't safely cast val because it may not be aligned, so use memcpy */
+        memcpy(&t, val, sizeof(struct _hr_time));
         QueryPerformanceCounter(&now);
         QueryPerformanceFrequency(&hfreq);
-        delta = (unsigned long) ((now.QuadPart - t->start.QuadPart) * 1000ul
+        delta = (unsigned long) ((now.QuadPart - t.start.QuadPart) * 1000ul
                                  / hfreq.QuadPart);
         return delta;
     }
@@ -277,17 +282,20 @@ void mbedtls_set_alarm(int seconds)
 
 unsigned long mbedtls_timing_get_timer(struct mbedtls_timing_hr_time *val, int reset)
 {
-    struct _hr_time *t = (struct _hr_time *) val;
+    struct _hr_time t;
 
     if (reset) {
-        gettimeofday(&t->start, NULL);
+        gettimeofday(&t.start, NULL);
+        memcpy(val, &t, sizeof(struct _hr_time));
         return 0;
     } else {
         unsigned long delta;
         struct timeval now;
+        /* We can't safely cast val because it may not be aligned, so use memcpy */
+        memcpy(&t, val, sizeof(struct _hr_time));
         gettimeofday(&now, NULL);
-        delta = (now.tv_sec  - t->start.tv_sec) * 1000ul
-                + (now.tv_usec - t->start.tv_usec) / 1000;
+        delta = (now.tv_sec  - t.start.tv_sec) * 1000ul
+                + (now.tv_usec - t.start.tv_usec) / 1000;
         return delta;
     }
 }

diff --git a/tests/suites/test_suite_timing.function b/tests/suites/test_suite_timing.function
@@ -29,8 +29,20 @@ void timing_hardclock()
 void timing_get_timer()
 {
     struct mbedtls_timing_hr_time time;
+
+    memset(&time, 0, sizeof(time));
+
     (void) mbedtls_timing_get_timer(&time, 1);
+
+    /* Check that a non-zero time was written back */
+    int all_zero = 1;
+    for (size_t i = 0; i < sizeof(time); i++) {
+        all_zero &= ((unsigned char *) &time)[i] == 0;
+    }
+    TEST_ASSERT(!all_zero);
+
     (void) mbedtls_timing_get_timer(&time, 0);
+
     /* This goto is added to avoid warnings from the generated code. */
     goto exit;
 }