crypto/openssh/openbsd-compat/explicit_bzero.c

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