netdev - Re: [PATCH net] net/sched: pfifo_fast: fix wrong dereference when qdisc is reset

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Message-ID: <20190827115031.43fcbac5@redhat.com>
Date:   Tue, 27 Aug 2019 11:50:31 +0200
From:   Stefano Brivio <sbrivio@...hat.com>
To:     Davide Caratti <dcaratti@...hat.com>
Cc:     Cong Wang <xiyou.wangcong@...il.com>,
        Jamal Hadi Salim <jhs@...atatu.com>,
        Jiri Pirko <jiri@...nulli.us>,
        "David S. Miller" <davem@...emloft.net>, netdev@...r.kernel.org,
        Paolo Abeni <pabeni@...hat.com>, Li Shuang <shuali@...hat.com>
Subject: Re: [PATCH net] net/sched: pfifo_fast: fix wrong dereference when
 qdisc is reset

On Tue, 27 Aug 2019 01:15:16 +0200
Davide Caratti <dcaratti@...hat.com> wrote:

> diff --git a/net/sched/sch_generic.c b/net/sched/sch_generic.c
> index 11c03cf4aa74..c89b787785a1 100644
> --- a/net/sched/sch_generic.c
> +++ b/net/sched/sch_generic.c
> @@ -688,12 +688,14 @@ static void pfifo_fast_reset(struct Qdisc *qdisc)
>  			kfree_skb(skb);
>  	}
>  
> -	for_each_possible_cpu(i) {
> -		struct gnet_stats_queue *q = per_cpu_ptr(qdisc->cpu_qstats, i);
> +	if (qdisc_is_percpu_stats(qdisc))

This needs curly brackets, as the block has multiple lines (for coding
style only).

> +		for_each_possible_cpu(i) {
> +			struct gnet_stats_queue *q =
> +				per_cpu_ptr(qdisc->cpu_qstats, i);

And you could split declaration and assignment here, it takes two lines
anyway and becomes more readable.

-- 
Stefano