Re: [PATCH v2 2/4] fix a realloc-related memory leak in localhost()

[Thomas Schwinge]

Hi!

On Mon, 15 Aug 2011 22:10:07 +0200, Jonathan Neuschäfer <j.neuschaefer@gmx.net> 
wrote:
>  * libshouldbeinlibc/localhost.c (localhost): assign the return value
>    of realloc to a temporary variable to avoid losing the old value of
>    buf in the case of realloc failing.
> ---
>  libshouldbeinlibc/localhost.c |   21 ++++++++++++++-------
>  1 files changed, 14 insertions(+), 7 deletions(-)
> 
> diff --git a/libshouldbeinlibc/localhost.c b/libshouldbeinlibc/localhost.c
> index f0c6754..f21f970 100644
> --- a/libshouldbeinlibc/localhost.c
> +++ b/libshouldbeinlibc/localhost.c
> @@ -39,18 +39,25 @@ localhost ()
>       errno = 0;
>  
>       if (buf) {
> +       char *new;
>         buf_len += buf_len;
> -       buf = realloc (buf, buf_len);
> +       new = realloc (buf, buf_len);
> +       if (! new)
> +         {

Am I being dense (which is entirely possible), or did you mean to ``free
(buf)'' here, or what is the intent here?

> +           errno = ENOMEM;
> +           return 0;
> +         }
> +       else
> +         buf = new;
>       } else {
>         buf_len = 128;        /* Initial guess */
>         buf = malloc (buf_len);
> +       if (! buf)
> +         {
> +           errno = ENOMEM;
> +           return 0;
> +         }
>       }
> -
> -     if (! buf)
> -       {
> -         errno = ENOMEM;
> -         return 0;
> -       }
>        } while ((gethostname(buf, buf_len) == 0 && !memchr (buf, '\0', 
> buf_len))
>              || errno == ENAMETOOLONG);
>  


Grüße,
 Thomas

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