Revert to not enabling asm under Memsan
Signed-off-by: Dave Rodgman <dave.rodgman@arm.com>
diff --git a/library/constant_time_impl.h b/library/constant_time_impl.h
index b2ef73f..8570928 100644
--- a/library/constant_time_impl.h
+++ b/library/constant_time_impl.h
@@ -37,11 +37,18 @@
#include "mbedtls/bignum.h"
#endif
-#include "../tests/include/test/constant_flow.h"
+/* Disable asm under Memsan because it confuses Memsan and generates false errors */
+#if defined(MBEDTLS_TEST_CONSTANT_FLOW_MEMSAN)
+#define MBEDTLS_CT_NO_ASM
+#elif defined(__has_feature)
+#if __has_feature(memory_sanitizer)
+#define MBEDTLS_CT_NO_ASM
+#endif
+#endif
/* armcc5 --gnu defines __GNUC__ but doesn't support GNU's extended asm */
#if defined(MBEDTLS_HAVE_ASM) && defined(__GNUC__) && (!defined(__ARMCC_VERSION) || \
- __ARMCC_VERSION >= 6000000)
+ __ARMCC_VERSION >= 6000000) && !defined(MBEDTLS_CT_NO_ASM)
#define MBEDTLS_CT_ASM
#if (defined(__arm__) || defined(__thumb__) || defined(__thumb2__))
#define MBEDTLS_CT_ARM_ASM
@@ -84,20 +91,7 @@
static inline mbedtls_ct_uint_t mbedtls_ct_compiler_opaque(mbedtls_ct_uint_t x)
{
#if defined(MBEDTLS_CT_ASM)
- /* Prevent false positives from Memsan - otherwise it will report the asm as
- * accessing secret data. */
- TEST_CF_SAVE_SECRET(x);
-
asm volatile ("" : [x] "+r" (x) :);
-
- /* Mark the return value as secret (if it was previously marked secret).
- * This is needed so that code of the form:
- *
- * if (mbedtls_ct_compiler_opaque(secret)) { ... }
- *
- * will fail const-flow tests.
- */
- TEST_CF_RESTORE_SECRET(x);
return x;
#else
return x ^ mbedtls_ct_zero;
diff --git a/tests/include/test/constant_flow.h b/tests/include/test/constant_flow.h
index ff464e6..f3d676e 100644
--- a/tests/include/test/constant_flow.h
+++ b/tests/include/test/constant_flow.h
@@ -32,27 +32,14 @@
* #define TEST_CF_SECRET(ptr, size)
* #define TEST_CF_PUBLIC(ptr, size)
*
- * and
- *
- * #define TEST_CF_SAVE_SECRET(variable)
- * #define TEST_CF_RESTORE_SECRET(variable)
- *
* that can be used in tests to mark a memory area as secret (no branch or
* memory access should depend on it) or public (default, only needs to be
* marked explicitly when it was derived from secret data).
*
- * The SAVE/RESTORE forms mark a variable as public, and subsequently restore its
- * previous secret/not-secret state. This is used where library code is generating
- * false positives and needs to temporarily disable Memsan checks for a particular
- * variable, and then restore it's original state afterwards so it doesn't interfere
- * with other checks.
- *
* Arguments:
* - ptr: a pointer to the memory area to be marked
* - size: the size in bytes of the memory area
*
- * - variable: a variable name
- *
* Implementation:
* The basic idea is that of ctgrind <https://github.com/agl/ctgrind>: we can
* re-use tools that were designed for checking use of uninitialized memory.
@@ -76,12 +63,6 @@
#define TEST_CF_PUBLIC __msan_unpoison
// void __msan_unpoison(const volatile void *a, size_t size);
-#define TEST_CF_SAVE_SECRET(_x) \
- int _test_cf_is_public_ ## _x = __msan_test_shadow(&(_x), sizeof(_x)) == -1; \
- TEST_CF_PUBLIC(&(_x), sizeof(_x));
-#define TEST_CF_RESTORE_SECRET(_x) \
- if (!_test_cf_is_public_ ## _x) TEST_CF_SECRET(&(_x), sizeof(_x));
-
#elif defined(MBEDTLS_TEST_CONSTANT_FLOW_VALGRIND)
#include <valgrind/memcheck.h>
@@ -90,18 +71,12 @@
#define TEST_CF_PUBLIC VALGRIND_MAKE_MEM_DEFINED
// VALGRIND_MAKE_MEM_DEFINED(_qzz_addr, _qzz_len)
-#define TEST_CF_SAVE_SECRET(_x)
-#define TEST_CF_RESTORE_SECRET(_x)
-
#else /* MBEDTLS_TEST_CONSTANT_FLOW_MEMSAN ||
MBEDTLS_TEST_CONSTANT_FLOW_VALGRIND */
#define TEST_CF_SECRET(ptr, size)
#define TEST_CF_PUBLIC(ptr, size)
-#define TEST_CF_SAVE_SECRET(_x)
-#define TEST_CF_RESTORE_SECRET(_x)
-
#endif /* MBEDTLS_TEST_CONSTANT_FLOW_MEMSAN ||
MBEDTLS_TEST_CONSTANT_FLOW_VALGRIND */