Increase okm_hex buffer to contain null character
Add an additional byte for the `okm_hex` buffer, to assure
it is null-terminated in case `okm` is 128 bytes long.
diff --git a/tests/suites/test_suite_hkdf.function b/tests/suites/test_suite_hkdf.function
index d2d6659..3e87207 100644
--- a/tests/suites/test_suite_hkdf.function
+++ b/tests/suites/test_suite_hkdf.function
@@ -21,9 +21,9 @@
unsigned char okm[128] = { '\0' };
/*
* okm_hex is the string representation of okm,
- * so its size is twice the size of okm.
+ * so its size is twice the size of okm, and an extra null-termination.
*/
- unsigned char okm_hex[256] = { '\0' };
+ unsigned char okm_hex[257] = { '\0' };
const mbedtls_md_info_t *md = mbedtls_md_info_from_type( md_alg );
TEST_ASSERT( md != NULL );