netdev - Re: [PATCH 2/2] netfilter: revert "conntrack: silent a memory leak warning"

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Message-ID: <20191008060414.GB25052@breakpoint.cc>
Date:   Tue, 8 Oct 2019 08:04:14 +0200
From:   Florian Westphal <fw@...len.de>
To:     Maciej Żenczykowski <zenczykowski@...il.com>
Cc:     Maciej Żenczykowski <maze@...gle.com>,
        "David S . Miller" <davem@...emloft.net>, netdev@...r.kernel.org,
        Cong Wang <xiyou.wangcong@...il.com>,
        Eric Dumazet <edumazet@...gle.com>,
        Pablo Neira Ayuso <pablo@...filter.org>
Subject: Re: [PATCH 2/2] netfilter: revert "conntrack: silent a memory leak
 warning"

Maciej Żenczykowski <zenczykowski@...il.com> wrote:
> From: Maciej Żenczykowski <maze@...gle.com>
> 
> This reverts commit 114aa35d06d4920c537b72f9fa935de5dd205260.
> 
> By my understanding of kmemleak the reasoning for this patch
> is incorrect.  If kmemleak couldn't handle rcu we'd have it
> reporting leaks all over the place.  My belief is that this
> was instead papering over a real leak.

Perhaps, but note that this is related to nfct->ext, not nfct itself.

I think we could remove __krealloc and use krealloc directly with
a bit of changes in the nf_conntrack core to make sure we do not
access nfct->ext without holding a reference to nfct, and then drop
rcu protection of nfct->ext, I don't think its strictly required anymore.