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_EXPLICIT_MEMSET 19 20 void 21 explicit_bzero(void *p, size_t n) 22 { 23 (void)explicit_memset(p, 0, n); 24 } 25 26 #elif defined(HAVE_MEMSET_S) 27 28 void 29 explicit_bzero(void *p, size_t n) 30 { 31 if (n == 0) 32 return; 33 (void)memset_s(p, n, 0, n); 34 } 35 36 #else /* HAVE_MEMSET_S */ 37 38 /* 39 * Indirect bzero through a volatile pointer to hopefully avoid 40 * dead-store optimisation eliminating the call. 41 */ 42 static void (* volatile ssh_bzero)(void *, size_t) = bzero; 43 44 void 45 explicit_bzero(void *p, size_t n) 46 { 47 if (n == 0) 48 return; 49 /* 50 * clang -fsanitize=memory needs to intercept memset-like functions 51 * to correctly detect memory initialisation. Make sure one is called 52 * directly since our indirection trick above successfully confuses it. 53 */ 54 #if defined(__has_feature) 55 # if __has_feature(memory_sanitizer) 56 memset(p, 0, n); 57 # endif 58 #endif 59 60 ssh_bzero(p, n); 61 } 62 63 #endif /* HAVE_MEMSET_S */ 64 65 #endif /* HAVE_EXPLICIT_BZERO */ 66