Re: [patch] [trivial] fix NULL deref

[Daniel Jacobowitz <dan@codesourcery.com>]

On Thu, Sep 16, 2010 at 10:26:27AM -0700, Ali Lakhia wrote:
> Please see patch to fix NULL dereference in strchr() function. Thanks.

Interesting.  How did you find this problem?  I don't think this
function can ever be called.

> 
> -Ali
> 
> --- gdb-7.1/gdb/fork-child.c    2009-12-31 23:31:31.000000000 -0800
> +++ gdb-7.1/gdb/fork-child.c 2010-09-16 10:17:25.000000000 -0700
> @@ -52,7 +52,7 @@
>  static void
>  breakup_args (char *scratch, char **argv)
>  {
> -  char *cp = scratch;
> +  char *cp = scratch, *tmp;
> 
>    for (;;)
>      {
> @@ -68,15 +68,16 @@
>        *argv++ = cp;
> 
>        /* Scan for next arg separator.  */
> -      cp = strchr (cp, ' ');
> -      if (cp == NULL)
> -       cp = strchr (cp, '\t');
> -      if (cp == NULL)
> -       cp = strchr (cp, '\n');
> +      tmp = strchr (cp, ' ');
> +      if (tmp == NULL)
> +       tmp = strchr (cp, '\t');
> +      if (tmp == NULL)
> +       tmp = strchr (cp, '\n');
> 
>        /* No separators => end of string => break.  */
> -      if (cp == NULL)
> +      if (tmp == NULL)
>         break;
> +      cp = tmp;
> 
>        /* Replace the separator with a terminator.  */
>        *cp++ = '\0';
> 

-- 
Daniel Jacobowitz
CodeSourcery