Test memcmp with differences starting after the first byte
Signed-off-by: Dave Rodgman <dave.rodgman@arm.com>
diff --git a/tests/suites/test_suite_constant_time.data b/tests/suites/test_suite_constant_time.data
index 2ea3e3e..91a25fa 100644
--- a/tests/suites/test_suite_constant_time.data
+++ b/tests/suites/test_suite_constant_time.data
@@ -14,25 +14,25 @@
mbedtls_ct_memcmp_null
mbedtls_ct_memcmp len 1
-mbedtls_ct_memcmp:1:1:0
+mbedtls_ct_memcmp:-1:1:0
mbedtls_ct_memcmp len 3
-mbedtls_ct_memcmp:1:3:0
+mbedtls_ct_memcmp:-1:3:0
mbedtls_ct_memcmp len 4
-mbedtls_ct_memcmp:1:4:0
+mbedtls_ct_memcmp:-1:4:0
mbedtls_ct_memcmp len 5
-mbedtls_ct_memcmp:1:5:0
+mbedtls_ct_memcmp:-1:5:0
mbedtls_ct_memcmp len 15
-mbedtls_ct_memcmp:1:15:0
+mbedtls_ct_memcmp:-1:15:0
mbedtls_ct_memcmp len 16
-mbedtls_ct_memcmp:1:16:0
+mbedtls_ct_memcmp:-1:16:0
mbedtls_ct_memcmp len 17
-mbedtls_ct_memcmp:1:17:0
+mbedtls_ct_memcmp:-1:17:0
mbedtls_ct_memcmp len 1 different
mbedtls_ct_memcmp:0:1:0
@@ -40,38 +40,56 @@
mbedtls_ct_memcmp len 17 different
mbedtls_ct_memcmp:0:17:0
+mbedtls_ct_memcmp len 17 different 1
+mbedtls_ct_memcmp:1:17:0
+
+mbedtls_ct_memcmp len 17 different 4
+mbedtls_ct_memcmp:4:17:0
+
+mbedtls_ct_memcmp len 17 different 10
+mbedtls_ct_memcmp:10:17:0
+
+mbedtls_ct_memcmp len 17 different 16
+mbedtls_ct_memcmp:16:17:0
+
mbedtls_ct_memcmp len 1 offset 1 different
mbedtls_ct_memcmp:0:1:1
mbedtls_ct_memcmp len 17 offset 1 different
mbedtls_ct_memcmp:0:17:1
-mbedtls_ct_memcmp len 1 offset 1
-mbedtls_ct_memcmp:1:1:1
-
-mbedtls_ct_memcmp len 1 offset 2
-mbedtls_ct_memcmp:1:1:2
-
-mbedtls_ct_memcmp len 1 offset 3
-mbedtls_ct_memcmp:1:1:3
-
-mbedtls_ct_memcmp len 5 offset 1
-mbedtls_ct_memcmp:1:5:1
-
-mbedtls_ct_memcmp len 5 offset 2
-mbedtls_ct_memcmp:1:5:2
-
-mbedtls_ct_memcmp len 5 offset 3
-mbedtls_ct_memcmp:1:5:3
-
-mbedtls_ct_memcmp len 17 offset 1
+mbedtls_ct_memcmp len 17 offset 1 different 1
mbedtls_ct_memcmp:1:17:1
+mbedtls_ct_memcmp len 17 offset 1 different 5
+mbedtls_ct_memcmp:5:17:1
+
+mbedtls_ct_memcmp len 1 offset 1
+mbedtls_ct_memcmp:-1:1:1
+
+mbedtls_ct_memcmp len 1 offset 2
+mbedtls_ct_memcmp:-1:1:2
+
+mbedtls_ct_memcmp len 1 offset 3
+mbedtls_ct_memcmp:-1:1:3
+
+mbedtls_ct_memcmp len 5 offset 1
+mbedtls_ct_memcmp:-1:5:1
+
+mbedtls_ct_memcmp len 5 offset 2
+mbedtls_ct_memcmp:-1:5:2
+
+mbedtls_ct_memcmp len 5 offset 3
+mbedtls_ct_memcmp:-1:5:3
+
+mbedtls_ct_memcmp len 17 offset 1
+mbedtls_ct_memcmp:-1:17:1
+
mbedtls_ct_memcmp len 17 offset 2
-mbedtls_ct_memcmp:1:17:2
+mbedtls_ct_memcmp:-1:17:2
mbedtls_ct_memcmp len 17 offset 3
-mbedtls_ct_memcmp:1:17:3
+mbedtls_ct_memcmp:-1:17:3
mbedtls_ct_memcpy_if_eq len 1 offset 0
mbedtls_ct_memcpy_if_eq:1:1:0
diff --git a/tests/suites/test_suite_constant_time.function b/tests/suites/test_suite_constant_time.function
index aa605d2..167962f 100644
--- a/tests/suites/test_suite_constant_time.function
+++ b/tests/suites/test_suite_constant_time.function
@@ -35,9 +35,17 @@
TEST_CF_SECRET(a + offset, size);
TEST_CF_SECRET(b + offset, size);
+ /* Construct data that matches, if same == -1, otherwise
+ * same gives the number of bytes (after the initial offset)
+ * that will match; after that it will differ.
+ */
for (int i = 0; i < size + offset; i++) {
a[i] = i & 0xff;
- b[i] = (i & 0xff) + (same ? 0 : 1);
+ if (same == -1 || (i - offset) < same) {
+ b[i] = a[i];
+ } else {
+ b[i] = (i + 1) & 0xff;
+ }
}
int reference = memcmp(a + offset, b + offset, size);
@@ -45,7 +53,7 @@
TEST_CF_PUBLIC(a + offset, size);
TEST_CF_PUBLIC(b + offset, size);
- if (same != 0) {
+ if (same == -1 || same >= size) {
TEST_ASSERT(reference == 0);
TEST_ASSERT(actual == 0);
} else {