netdev - Re: [net-next PATCH v3] udp: Resolve NULL pointer dereference over flow-based vxlan device

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Message-ID: <1463114613.23934.180.camel@edumazet-glaptop3.roam.corp.google.com>
Date:	Thu, 12 May 2016 21:43:33 -0700
From:	Eric Dumazet <eric.dumazet@...il.com>
To:	Alexander Duyck <aduyck@...antis.com>
Cc:	netdev@...r.kernel.org, davem@...emloft.net,
	alexander.duyck@...il.com, tgraf@...g.ch, tom@...bertland.com,
	jbenc@...hat.com
Subject: Re: [net-next PATCH v3] udp: Resolve NULL pointer dereference over
 flow-based vxlan device

On Thu, 2016-05-12 at 16:23 -0700, Alexander Duyck wrote:
> While testing an OpenStack configuration using VXLANs I saw the following
> call trace:

> The following trace is seen when receiving a DHCP request over a flow-based
> VXLAN tunnel.  I believe this is caused by the metadata dst having a NULL
> dev value and as a result dev_net(dev) is causing a NULL pointer dereference.
> 
> To resolve this I am replacing the check for skb_dst(skb)->dev with just
> skb->dev.  This makes sense as the callers of this function are usually in
> the receive path and as such skb->dev should always be populated.  In
> addition other functions in the area where these are called are already
> using dev_net(skb->dev) to determine the namespace the UDP packet belongs
> in.
> 
> Fixes: 63058308cd55 ("udp: Add udp6_lib_lookup_skb and udp4_lib_lookup_skb")
> Signed-off-by: Alexander Duyck <aduyck@...antis.com>
> ---

Acked-by: Eric Dumazet <edumazet@...gle.com>

Thanks ;)