Use explicit_bzero if available.

configure.ac

@@ -94,7 +94,7 @@ AC_SUBST(UUID_LIBS, $LIBS)
 LIBS=$saved_LIBS
 
 AC_SEARCH_LIBS([clock_gettime],[rt posix4])
-AC_CHECK_FUNCS([posix_memalign clock_gettime posix_fallocate])
+AC_CHECK_FUNCS([posix_memalign clock_gettime posix_fallocate explicit_bzero])
 
 if test "x$enable_largefile" = "xno"; then
   AC_MSG_ERROR([Building with --disable-largefile is not supported, it can cause data corruption.])

lib/crypto_backend/crypto_backend.h

@@ -124,8 +124,12 @@ int crypt_storage_encrypt(struct crypt_storage *ctx, uint64_t sector,
 /* Memzero helper (memset on stack can be optimized out) */
 static inline void crypt_backend_memzero(void *s, size_t n)
 {
+#ifdef HAVE_EXPLICIT_BZERO
+	explicit_bzero(s, n);
+#else
 	volatile uint8_t *p = (volatile uint8_t *)s;
 	while(n--) *p++ = 0;
+#endif
 }
 
 #endif /* _CRYPTO_BACKEND_H */

lib/utils_crypt.c

@@ -155,10 +155,14 @@ int crypt_parse_pbkdf(const char *s, const char **pbkdf)
  */
 void crypt_memzero(void *s, size_t n)
 {
+#ifdef HAVE_EXPLICIT_BZERO
+	explicit_bzero(s, n);
+#else
 	volatile uint8_t *p = (volatile uint8_t *)s;
 
 	while(n--)
 		*p++ = 0;
+#endif
 }
 
 /* safe allocations */