Subject: Re: [Patch net-next 2/5] net_sched: fix memory leak in cls_tcindex

From: John Fastabend <[email-masked]>
Date: Mon, 15 Sep 2014 14:41:43 -0700

On 09/15/2014 02:06 PM, Cong Wang wrote:
> Fixes: commit 331b72922c5f58d48fd ("net: sched: RCU cls_tcindex")
> Cc: John Fastabend <[email-masked]>
> Signed-off-by: Cong Wang <[email-masked]>
> ---
>  net/sched/cls_tcindex.c | 13 +++++++------
>  1 file changed, 7 insertions(+), 6 deletions(-)
> 
> diff --git a/net/sched/cls_tcindex.c b/net/sched/cls_tcindex.c
> index a02ca72..16ec1ed 100644
> --- a/net/sched/cls_tcindex.c
> +++ b/net/sched/cls_tcindex.c
> @@ -243,7 +243,7 @@ tcindex_set_parms(struct net *net, struct tcf_proto *tp, unsigned long base,
>  	 */
>  	cp = kzalloc(sizeof(*cp), GFP_KERNEL);
>  	if (!cp)
> -		return -ENOMEM;
> +		goto errout;

but you need to set 'err = -ENOMEM' then.

>  
>  	cp->mask = p->mask;
>  	cp->shift = p->shift;
> @@ -257,6 +257,7 @@ tcindex_set_parms(struct net *net, struct tcf_proto *tp, unsigned long base,
>  				      sizeof(*r) * cp->hash, GFP_KERNEL);
>  		if (!cp->perfect)
>  			goto errout;
> +		balloc = 1;

Actually can we just get rid of the balloc here altogether and
remove the checks in errout_alloc so that cp->perfect and cp->h
are freed unconditionally? They should be NULL if they are not
being used because of the kzalloc.

>  	}
>  	cp->h = p->h;
>  
> @@ -285,9 +286,9 @@ tcindex_set_parms(struct net *net, struct tcf_proto *tp, unsigned long base,
>  	if (cp->perfect) {
>  		if (!valid_perfect_hash(cp) ||
>  		    cp->hash > cp->alloc_hash)
> -			goto errout;
> +			goto errout_alloc;
>  	} else if (cp->h && cp->hash != cp->alloc_hash) {
> -		goto errout;
> +		goto errout_alloc;
>  	}
>  
>  	err = -EINVAL;
> @@ -314,7 +315,7 @@ tcindex_set_parms(struct net *net, struct tcf_proto *tp, unsigned long base,
>  	 */
>  	if (cp->perfect || valid_perfect_hash(cp))
>  		if (handle >= cp->alloc_hash)
> -			goto errout;
> +			goto errout_alloc;
>  
>  
>  	err = -ENOMEM;
> @@ -324,7 +325,7 @@ tcindex_set_parms(struct net *net, struct tcf_proto *tp, unsigned long base,
>  
>  			cp->perfect = kcalloc(cp->hash, sizeof(*r), GFP_KERNEL);
>  			if (!cp->perfect)
> -				goto errout;
> +				goto errout_alloc;
>  			for (i = 0; i < cp->hash; i++)
>  				tcf_exts_init(&cp->perfect[i].exts,
>  					      TCA_TCINDEX_ACT,
> @@ -338,7 +339,7 @@ tcindex_set_parms(struct net *net, struct tcf_proto *tp, unsigned long base,
>  				       GFP_KERNEL);
>  
>  			if (!hash)
> -				goto errout;
> +				goto errout_alloc;
>  
>  			cp->h = hash;
>  			balloc = 2;
>