- (djm) [openbsd-compat/explicit_bzero.c] implement explicit_bzero()

   using memset_s() where possible; improve fallback to indirect bzero
   via a volatile pointer to give it more of a chance to avoid being
   optimised away.

1 files changed, 23 insertions, 3 deletions

diff --git a/openbsd-compat/explicit_bzero.c b/openbsd-compat/explicit_bzero.c
index b106741e..3c85a484 100644
--- a/openbsd-compat/explicit_bzero.c
+++ b/openbsd-compat/explicit_bzero.c
@@ -7,14 +7,34 @@
 
 #include "includes.h"
 
+/*
+ * explicit_bzero - don't let the compiler optimize away bzero
+ */
+
 #ifndef HAVE_EXPLICIT_BZERO
 
+#ifdef HAVE_MEMSET_S
+
+void
+explicit_bzero(void *p, size_t n)
+{
+	(void)memset_s(p, n, 0, n);
+}
+
+#else /* HAVE_MEMSET_S */
+
 /*
- * explicit_bzero - don't let the compiler optimize away bzero
+ * Indirect bzero through a volatile pointer to hopefully avoid
+ * dead-store optimisation eliminating the call.
  */
+static void (* volatile ssh_bzero)(void *, size_t) = bzero;
+
 void
 explicit_bzero(void *p, size_t n)
 {
-	bzero(p, n);
+	ssh_bzero(p, n);
 }
-#endif
+
+#endif /* HAVE_MEMSET_S */
+
+#endif /* HAVE_EXPLICIT_BZERO */