linux-kernel - Re: [PATCH net] net: fix skb leak in __skb_tstamp

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Message-Id: <20230522171853.90173-1-sj@kernel.org>
Date:   Mon, 22 May 2023 17:18:53 +0000
From:   SeongJae Park <sj@...nel.org>
To:     Kuniyuki Iwashima <kuniyu@...zon.com>
Cc:     sj@...nel.org, davem@...emloft.net, edumazet@...gle.com,
        kuba@...nel.org, linux-kernel@...r.kernel.org,
        netdev@...r.kernel.org, nmanthey@...zon.de, pabeni@...hat.com,
        ptyadav@...zon.de, willemb@...gle.com
Subject: Re: [PATCH net] net: fix skb leak in __skb_tstamp_tx()

On Mon, 22 May 2023 10:04:30 -0700 Kuniyuki Iwashima <kuniyu@...zon.com> wrote:

> From: SeongJae Park <sj@...nel.org>
> Date: Mon, 22 May 2023 16:55:05 +0000
> > Hi Pratyush,
> > 
> > On Mon, 22 May 2023 17:30:20 +0200 Pratyush Yadav <ptyadav@...zon.de> wrote:
> > 
> > > Commit 50749f2dd685 ("tcp/udp: Fix memleaks of sk and zerocopy skbs with
> > > TX timestamp.") added a call to skb_orphan_frags_rx() to fix leaks with
> > > zerocopy skbs. But it ended up adding a leak of its own. When
> > > skb_orphan_frags_rx() fails, the function just returns, leaking the skb
> > > it just cloned. Free it before returning.
> > > 
> > > This bug was discovered and resolved using Coverity Static Analysis
> > > Security Testing (SAST) by Synopsys, Inc.
> > > 
> > > Fixes: 50749f2dd685 ("tcp/udp: Fix memleaks of sk and zerocopy skbs with TX timestamp.")
> > 
> > Seems the commit has merged in several stable kernels.  Is the bug also
> > affecting those?  If so, would it be better to Cc stable@...r.kernel.org?
> 
> In netdev, we add 'net' in Subject for bugfix, then netdev maintainers
> send a pull request weekly, and stable maintainers backport the fixes to
> affected trees.
> 
> So we usually need not CC stable for netdev patches.

Thank you for the nice explanation!  Seems it is also well documented at
https://www.kernel.org/doc/html/v5.10/networking/netdev-FAQ.html#q-i-see-a-network-patch-and-i-think-it-should-be-backported-to-stable

However, I don't show the 'net' subject rule on the document.  Is it documented
somewhere else?


Thanks,
SJ

> 
> Thanks,
> Kuniyuki
>