Re: [PATCH-V2] [nfs/nfs-utils/libtirpc] src/getnetconfig.c: fix a BAD_FREE (CWE-763)

[Steve Dickson <SteveD@RedHat.com>]

On 9/25/18 11:25 PM, Zhi Li wrote:
> Signed-off-by: Zhi Li <yieli@redhat.com>
> ---
> From steved:
> Ok... I see why tmp original value needs to be maintained
> to do the free()... but I'm wondering why the freeing
> of p->nc_netid is needed... it appears to me it is part
> of tmp string... so when tmp is freed won't p->nc_netid
> be freed as well?
> 
> Reply:
> Yes, you are right, p->nc_neti is a part of tmp string, so freeing tmp can make p->nc_neti be freed as well.
> I have update the issue.
> 
>  src/getnetconfig.c | 18 +++++++++---------
>  1 file changed, 9 insertions(+), 9 deletions(-)
Committed... 

steved.

> 
> diff --git a/src/getnetconfig.c b/src/getnetconfig.c
> index d67d97d..cfd33c2 100644
> --- a/src/getnetconfig.c
> +++ b/src/getnetconfig.c
> @@ -681,6 +681,7 @@ struct netconfig	*ncp;
>  {
>      struct netconfig	*p;
>      char	*tmp;
> +    char	*t;
>      u_int	i;
>  
>      if ((tmp=malloc(MAXNETCONFIGLINE)) == NULL)
> @@ -700,22 +701,21 @@ struct netconfig	*ncp;
>       */
>      *p = *ncp;
>      p->nc_netid = (char *)strcpy(tmp,ncp->nc_netid);
> -    tmp = strchr(tmp, 0) + 1;
> -    p->nc_protofmly = (char *)strcpy(tmp,ncp->nc_protofmly);
> -    tmp = strchr(tmp, 0) + 1;
> -    p->nc_proto = (char *)strcpy(tmp,ncp->nc_proto);
> -    tmp = strchr(tmp, 0) + 1;
> -    p->nc_device = (char *)strcpy(tmp,ncp->nc_device);
> +    t = strchr(tmp, 0) + 1;
> +    p->nc_protofmly = (char *)strcpy(t,ncp->nc_protofmly);
> +    t = strchr(t, 0) + 1;
> +    p->nc_proto = (char *)strcpy(t,ncp->nc_proto);
> +    t = strchr(t, 0) + 1;
> +    p->nc_device = (char *)strcpy(t,ncp->nc_device);
>      p->nc_lookups = (char **)malloc((size_t)(p->nc_nlookups+1) * sizeof(char *));
>      if (p->nc_lookups == NULL) {
> -	free(p->nc_netid);
>  	free(p);
>  	free(tmp);
>  	return(NULL);
>      }
>      for (i=0; i < p->nc_nlookups; i++) {
> -    	tmp = strchr(tmp, 0) + 1;
> -    	p->nc_lookups[i] = (char *)strcpy(tmp,ncp->nc_lookups[i]);
> +	t = strchr(t, 0) + 1;
> +	p->nc_lookups[i] = (char *)strcpy(t,ncp->nc_lookups[i]);
>      }
>      return(p);
>  }
>