[PATCH] os: prevent negative array index access (#80890)

[walter harms]

Am 08.07.2014 01:24, schrieb Peter Hutterer:
> If an empty string is provided to LogMessageVerbSigSafe, the length of the
> printed string is 0.
> 
> Read-only access only and the only effect it had was adding a linebreak or not.
> 
> X.Org Bug 80890 <http://bugs.freedesktop.org/show_bug.cgi?id=80890>
> 
> Signed-off-by: Peter Hutterer <peter.hutterer at who-t.net>
> ---
> Keith, please merge this directly if you're happy with it.
> 
>  os/log.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/os/log.c b/os/log.c
> index a368569..2a721b9 100644
> --- a/os/log.c
> +++ b/os/log.c
> @@ -697,7 +697,7 @@ LogVMessageVerbSigSafe(MessageType type, int verb, const char *format, va_list a
>      if (sizeof(buf) - len == 1)
>          buf[len - 1] = '\n';
>  
> -    newline = (buf[len - 1] == '\n');
> +    newline = (len > 0 && buf[len - 1] == '\n');
>      LogSWrite(verb, buf, len, newline);
>  }
>  

would it be more easy to
  if (len <=0)
        return ;
re,
 wh