xref: /netbsd-src/external/bsd/pam-u2f/dist/explicit_bzero.c (revision 46988a0ecd54772d66eec56f0d4d6a35a553f49b)
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