From: Florian Westphal <fw@strlen.de>
To: gfree.wind@vip.163.com
Cc: dsa@cumulusnetworks.com, shm@cumulusnetworks.com,
davem@davemloft.net, netdev@vger.kernel.org
Subject: Re: [PATCH net] driver: vrf: Fix one possible use-after-free issue
Date: Tue, 9 May 2017 11:21:02 +0200 [thread overview]
Message-ID: <20170509092102.GB16263@breakpoint.cc> (raw)
In-Reply-To: <1494320069-39638-1-git-send-email-gfree.wind@vip.163.com>
gfree.wind@vip.163.com <gfree.wind@vip.163.com> wrote:
> When one netfilter rule or hook stoles the skb and return NF_STOLEN,
> it means the skb is taken by the rule, and other modules should not
> touch this skb ever. Maybe the skb is queued or freed directly by the
> rule.
>
> Now uses the nf_hook instead of NF_HOOK to get the result of netfilter,
> and check the return value of nf_hook. Only when its value equals 1, it
> means the skb could go ahead. Or reset the skb as NULL.
>
> BTW, because vrf_rcv_finish is empty function, so needn't invoke it
> even though nf_hook returns 1.
Thats a bug then.
The okfn (if called) takes ownership of skb and must free it eventually.
Otherwise userspace queueing leaks skb on reinjection.
(see nf_reinject() and its use of okfn()).
next prev parent reply other threads:[~2017-05-09 9:21 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-05-09 8:54 [PATCH net] driver: vrf: Fix one possible use-after-free issue gfree.wind
2017-05-09 9:21 ` Florian Westphal [this message]
2017-05-09 9:41 ` Gao Feng
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