netdev - Re: [PATCH v1 net] packet: handle too big packets for PACKET

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Date:	Mon, 18 Aug 2014 17:39:02 +0200
From:	Daniel Borkmann <dborkman@...hat.com>
To:	Eric Dumazet <eric.dumazet@...il.com>
CC:	David Miller <davem@...emloft.net>,
	Hannes Frederic Sowa <hannes@...essinduktion.org>,
	Neil Horman <nhorman@...driver.com>,
	Jesper Dangaard Brouer <brouer@...hat.com>,
	netdev <netdev@...r.kernel.org>, Guy Harris <guy@...m.mit.edu>
Subject: Re: [PATCH v1 net] packet: handle too big packets for PACKET_V3

On 08/15/2014 06:16 PM, Eric Dumazet wrote:
> From: Eric Dumazet <edumazet@...gle.com>
>
> af_packet can currently overwrite kernel memory by out of bound
> accesses, because it assumed a [new] block can always hold one frame.
>
> This is not generally the case, even if most existing tools do it right.
>
> This patch clamps too long frames as API permits, and issue a one time
> error on syslog.
>
> [  394.357639] tpacket_rcv: packet too big, clamped from 5042 to 3966. macoff=82
>
> In this example, packet header tp_snaplen was set to 3966,
> and tp_len was set to 5042 (skb->len)
>
> Signed-off-by: Eric Dumazet <edumazet@...gle.com>
> Fixes: f6fb8f100b80 ("af-packet: TPACKET_V3 flexible buffer implementation.")

Acked-by: Daniel Borkmann <dborkman@...hat.com>

This looks good to me, thanks Eric!

[ Truly dislike the TPACKET_V3 code ... :/ ]
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