From: Davide Caratti <dcaratti@redhat.com>
To: Colin King <colin.king@canonical.com>,
Jamal Hadi Salim <jhs@mojatatu.com>,
Cong Wang <xiyou.wangcong@gmail.com>,
Jiri Pirko <jiri@resnulli.us>,
"David S . Miller" <davem@davemloft.net>,
Gautam Ramakrishnan <gautamramk@gmail.com>,
"Sachin D . Patil" <sdp.sachin@gmail.com>,
Mohit Bhasi <mohitbhasi1998@gmail.com>,
Leslie Monis <lesliemonis@gmail.com>,
"Mohit P . Tahiliani" <tahiliani@nitk.edu.in>,
netdev@vger.kernel.org
Cc: kernel-janitors@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH] net: sched: Fix potential infinite loop
Date: Wed, 07 Apr 2021 22:20:08 +0200 [thread overview]
Message-ID: <4396d0b86d66afa1d3211403b48a15a4d0a03e55.camel@redhat.com> (raw)
In-Reply-To: <20210407163808.499027-1-colin.king@canonical.com>
hello Colin, and thanks for your patch!
On Wed, 2021-04-07 at 17:38 +0100, Colin King wrote:
> From: Colin Ian King <colin.king@canonical.com>
>
> The for-loop iterates with a u16 loop counter idx and compares this
> with the loop upper limit of q->flows_cnt that is a u32 type.
the value of 'flows_cnt' has 65535 as an upper bound in the ->init()
function, so it should be safe to use an u16 for 'idx'. (BTW, the
infinite loop loop was a real thing, see [1] :) ).
> There is a potential infinite loop if q->flows_cnt is larger than
> the u8 loop counter.
(u16 loop counter, IIUC)
> Fix this by making the loop counter the same
> type as q->flows_cnt.
the same 'for' loop is in fq_pie_init() and fq_pie_reset(): so, in my
opinion just changing fq_pie_timer() to fix an infinite loop is not very
useful: 'idx' is also used as an index for q->flows[], that's allocated
in [2]. Maybe (but I might be wrong) just allowing bigger values might
potentially cause other covscan warnings. WDYT?
> Addresses-Coverity: ("Infinite loop")
> Fixes: ec97ecf1ebe4 ("net: sched: add Flow Queue PIE packet scheduler")
> Signed-off-by: Colin Ian King <colin.king@canonical.com>
thanks!
--
davide
[1] https://lore.kernel.org/netdev/416eb03a8ca70b5dfb5e882e2752b7fc13c42f92.1590537338.git.dcaratti@redhat.com/
[2] https://elixir.bootlin.com/linux/latest/source/net/sched/sch_fq_pie.c#L417
prev parent reply other threads:[~2021-04-07 20:20 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-04-07 16:38 [PATCH] net: sched: Fix potential infinite loop Colin King
2021-04-07 20:20 ` Davide Caratti [this message]
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