Re: New Microsoft Security Tool for developers

[Steve Litt <slitt () troubleshooters com>]

Oh Oh, what about this:

if(noOverflow("\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0")) {
  printf("No overflow unless the 10th char of the string was \\0\n");
}

SteveT


> bool noOverflow(char *str)
> {
>      char buffer[10];
>
>      if( str == NULL )
>      {
>          /* We should never have a NULL string */
>           assert( false );
>           return false;
>      }
>
>      /* Lets prep our buffer to check for an overflow. Lets nullify the end
> char first */
>      buffer[sizeof(buffer)-1] = '\0';
>
>     /* Lets copy the string in, max of buffer size */
>     strncpy( buffer, str, sizeof(buffer) );
>
>     /* Now lets check if the null at the end of the buffer has been
> trampled */
>     if( buffer[sizeof(buffer)-1] != '\0' )
>     {
>           /* We know of an unsafe string. This has overflowed! */
>           return false;
>      }
>
>      /* Avoiding buffer flow with the above two lines */
>      return true;
> }