netdev - Re: [v2 PATCH 1/2] macvlan: Fix potential use-after free for broadcasts

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Date:	Tue, 31 May 2016 21:19:37 -0700
From:	Cong Wang <xiyou.wangcong@...il.com>
To:	Herbert Xu <herbert@...dor.apana.org.au>
Cc:	David Miller <davem@...emloft.net>,
	Lennert Buytenhek <buytenh@...tstofly.org>,
	Patrick McHardy <kaber@...sh.net>,
	Linux Kernel Network Developers <netdev@...r.kernel.org>,
	Jiri Pirko <jpirko@...hat.com>
Subject: Re: [v2 PATCH 1/2] macvlan: Fix potential use-after free for broadcasts

On Tue, May 31, 2016 at 8:43 PM, Herbert Xu <herbert@...dor.apana.org.au> wrote:
> When we postpone a broadcast packet we save the source port in
> the skb if it is local.  However, the source port can disappear
> before we get a chance to process the packet.
>

Hmm, why could this happen? The upper device should be linked
with the lower device, where a refcount is already held.
Also, the work is cancelled in ->uninit().