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From: Cong Wang <xiyou.wangcong@gmail.com>
To: Dan Carpenter <dan.carpenter@oracle.com>
Cc: Jamal Hadi Salim <jhs@mojatatu.com>,
	Jiri Pirko <jiri@resnulli.us>,
	"David S. Miller" <davem@davemloft.net>,
	Jakub Kicinski <kuba@kernel.org>,
	Mohit Bhasi <mohitbhasi1998@gmail.com>,
	"Mohit P. Tahiliani" <tahiliani@nitk.edu.in>,
	"V. Saicharan" <vsaicharan1998@gmail.com>,
	Gautam Ramakrishnan <gautamramk@gmail.com>,
	Linux Kernel Network Developers <netdev@vger.kernel.org>,
	kernel-janitors@vger.kernel.org
Subject: Re: [PATCH net] net: sched: prevent a use after free
Date: Sat, 1 Feb 2020 11:38:43 -0800	[thread overview]
Message-ID: <CAM_iQpUYv9vEVpYc-WfMNfCc9QaBzmTYs66-GEfwOKiqOXHxew@mail.gmail.com> (raw)
In-Reply-To: <20200131065647.joonbg3wzcw26x3b@kili.mountain>

On Thu, Jan 30, 2020 at 10:57 PM Dan Carpenter <dan.carpenter@oracle.com> wrote:
>
> The code calls kfree_skb(skb); and then re-uses "skb" on the next line.
> Let's re-order these lines to solve the problem.
>
> Fixes: ec97ecf1ebe4 ("net: sched: add Flow Queue PIE packet scheduler")
> Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
> ---
>  net/sched/sch_fq_pie.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/net/sched/sch_fq_pie.c b/net/sched/sch_fq_pie.c
> index bbd0dea6b6b9..78472e0773e9 100644
> --- a/net/sched/sch_fq_pie.c
> +++ b/net/sched/sch_fq_pie.c
> @@ -349,9 +349,9 @@ static int fq_pie_change(struct Qdisc *sch, struct nlattr *opt,
>         while (sch->q.qlen > sch->limit) {
>                 struct sk_buff *skb = fq_pie_qdisc_dequeue(sch);
>
> -               kfree_skb(skb);
>                 len_dropped += qdisc_pkt_len(skb);
>                 num_dropped += 1;
> +               kfree_skb(skb);

Or even better: use rtnl_kfree_skbs().

Thanks.

  reply	other threads:[~2020-02-01 19:38 UTC|newest]

Thread overview: 8+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-01-31  6:56 [PATCH net] net: sched: prevent a use after free Dan Carpenter
2020-02-01 19:38 ` Cong Wang [this message]
2020-02-03  8:38   ` Dan Carpenter
2020-02-03 19:58     ` Cong Wang
2020-02-03 20:33       ` Cong Wang
2020-02-05 11:53         ` [PATCH v2 " Dan Carpenter
2020-02-05 18:03           ` Cong Wang
2020-02-06 13:01           ` David Miller

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