explicit_bzero.c revision 323134 
1/* OPENBSD ORIGINAL: lib/libc/string/explicit_bzero.c */
2/*	$OpenBSD: explicit_bzero.c,v 1.1 2014/01/22 21:06:45 tedu Exp $ */
3/*
4 * Public domain.
5 * Written by Ted Unangst
6 */
7
8#include "includes.h"
9
10#include <string.h>
11
12/*
13 * explicit_bzero - don't let the compiler optimize away bzero
14 */
15
16#ifndef HAVE_EXPLICIT_BZERO
17
18#ifdef HAVE_MEMSET_S
19
20void
21explicit_bzero(void *p, size_t n)
22{
23	(void)memset_s(p, n, 0, n);
24}
25
26#else /* HAVE_MEMSET_S */
27
28/*
29 * Indirect bzero through a volatile pointer to hopefully avoid
30 * dead-store optimisation eliminating the call.
31 */
32static void (* volatile ssh_bzero)(void *, size_t) = bzero;
33
34void
35explicit_bzero(void *p, size_t n)
36{
37	/*
38	 * clang -fsanitize=memory needs to intercept memset-like functions
39	 * to correctly detect memory initialisation. Make sure one is called
40	 * directly since our indirection trick above sucessfully confuses it.
41	 */
42#if defined(__has_feature)
43# if __has_feature(memory_sanitizer)
44	memset(p, 0, n);
45# endif
46#endif
47
48	ssh_bzero(p, n);
49}
50
51#endif /* HAVE_MEMSET_S */
52
53#endif /* HAVE_EXPLICIT_BZERO */
54