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 "openbsd-compat.h"
9
10 #if !defined(HAVE_EXPLICIT_BZERO) && !defined(_WIN32)
11
12 #include <string.h>
13
14 /*
15 * explicit_bzero - don't let the compiler optimize away bzero
16 */
17
18 #ifdef HAVE_MEMSET_S
19
20 void
explicit_bzero(void * p,size_t n)21 explicit_bzero(void *p, size_t n)
22 {
23 if (n == 0)
24 return;
25 (void)memset_s(p, n, 0, n);
26 }
27
28 #else /* HAVE_MEMSET_S */
29
30 /*
31 * Indirect bzero through a volatile pointer to hopefully avoid
32 * dead-store optimisation eliminating the call.
33 */
34 static void (* volatile ssh_bzero)(void *, size_t) = bzero;
35
36 void
explicit_bzero(void * p,size_t n)37 explicit_bzero(void *p, size_t n)
38 {
39 if (n == 0)
40 return;
41 /*
42 * clang -fsanitize=memory needs to intercept memset-like functions
43 * to correctly detect memory initialisation. Make sure one is called
44 * directly since our indirection trick above successfully confuses it.
45 */
46 #if defined(__has_feature)
47 # if __has_feature(memory_sanitizer)
48 memset(p, 0, n);
49 # endif
50 #endif
51
52 ssh_bzero(p, n);
53 }
54
55 #endif /* HAVE_MEMSET_S */
56
57 #endif /* !defined(HAVE_EXPLICIT_BZERO) && !defined(_WIN32) */
58