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
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 #if defined(ANDROID)
35 static void (* volatile ssh_bzero)(void *, size_t) = __bionic_bzero;
36 #else
37 static void (* volatile ssh_bzero)(void *, size_t) = bzero;
38 #endif
39
40 void
explicit_bzero(void * p,size_t n)41 explicit_bzero(void *p, size_t n)
42 {
43 if (n == 0)
44 return;
45 /*
46 * clang -fsanitize=memory needs to intercept memset-like functions
47 * to correctly detect memory initialisation. Make sure one is called
48 * directly since our indirection trick above successfully confuses it.
49 */
50 #if defined(__has_feature)
51 # if __has_feature(memory_sanitizer)
52 memset(p, 0, n);
53 # endif
54 #endif
55
56 ssh_bzero(p, n);
57 }
58
59 #endif /* HAVE_MEMSET_S */
60
61 #endif /* HAVE_EXPLICIT_BZERO */
62