Add explanatory comment
Signed-off-by: Dave Rodgman <dave.rodgman@arm.com>
diff --git a/tests/suites/test_suite_platform_util.function b/tests/suites/test_suite_platform_util.function
index d6d6d1f..a4c1143 100644
--- a/tests/suites/test_suite_platform_util.function
+++ b/tests/suites/test_suite_platform_util.function
@@ -43,6 +43,16 @@
/* BEGIN_CASE */
void mbedtls_platform_zeroize_uninitialised(int len, int p)
{
+ /*
+ * As per #7301: on some platforms, including modern Linux, Clang with Msan
+ * does not recognize that explicit_bzero() writes well-defined content to
+ * its output buffer. For us, this causes CMAC operations to fail in Msan
+ * builds when mbedtls_platform_zeroize() is implemented over
+ * explicit_bzero().
+ *
+ * This test ensures we have a simple/obvious MSan test rather than
+ * spurious errors in crypto code that are hard to track down.
+ */
char buf[128];
mbedtls_platform_zeroize(buf, len);