xref: /freebsd/crypto/openssh/openbsd-compat/explicit_bzero.c (revision a35f04fba2ebb8f86d4cbdc710c89a094572b08e)
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
21 explicit_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  */
32 static void (* volatile ssh_bzero)(void *, size_t) = bzero;
33 
34 void
35 explicit_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