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

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Date:	Mon, 15 Sep 2014 15:15:34 -0700
From:	Cong Wang <xiyou.wangcong@...il.com>
To:	John Fastabend <john.r.fastabend@...el.com>
Cc:	Linux Kernel Network Developers <netdev@...r.kernel.org>,
	john fastabend <john.fastabend@...il.com>,
	"David S. Miller" <davem@...emloft.net>
Subject: Re: [Patch net-next 2/5] net_sched: fix memory leak in cls_tcindex

On Mon, Sep 15, 2014 at 2:41 PM, John Fastabend
<john.r.fastabend@...el.com> wrote:
> On 09/15/2014 02:06 PM, Cong Wang wrote:
>> Fixes: commit 331b72922c5f58d48fd ("net: sched: RCU cls_tcindex")
>> Cc: John Fastabend <john.fastabend@...il.com>
>> Signed-off-by: Cong Wang <xiyou.wangcong@...il.com>
>> ---
>>  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.

Yeah, I thought err is initialized to ENOMEM.

>
>>
>>       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.
>

Hmm, but for cp->h which you don't duplicate if we free it we
free p->h too, which seems not expected. I think we probably
need to cp->h = kmemdup(p->h) as well.
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