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 <string.h>
9
10 /*
11 * explicit_bzero - don't let the compiler optimize away bzero
12 */
13
14 #ifndef HAVE_EXPLICIT_BZERO
15
16 #include "util.h"
17
18 #ifdef HAVE_MEMSET_S
19
explicit_bzero(void * p,size_t n)20 void explicit_bzero(void *p, size_t n) {
21 if (n == 0)
22 return;
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 */
32 static void (*volatile ssh_bzero)(void *, size_t) = bzero;
33
explicit_bzero(void * p,size_t n)34 void explicit_bzero(void *p, size_t n) {
35 if (n == 0)
36 return;
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 successfully 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