netdev - Re: [PATCH] dccp: fix freeing skb too early for IPV6

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Message-Id: <20170217.133708.1915562990938384609.davem@davemloft.net>
Date:   Fri, 17 Feb 2017 13:37:08 -0500 (EST)
From:   David Miller <davem@...emloft.net>
To:     andreyknvl@...gle.com
Cc:     netdev@...r.kernel.org, edumazet@...gle.com, gerrit@....abdn.ac.uk,
        dvyukov@...gle.com, kcc@...gle.com, glider@...gle.com
Subject: Re: [PATCH] dccp: fix freeing skb too early for IPV6_RECVPKTINFO

From: Andrey Konovalov <andreyknvl@...gle.com>
Date: Thu, 16 Feb 2017 17:22:46 +0100

> In the current DCCP implementation an skb for a DCCP_PKT_REQUEST packet
> is forcibly freed via __kfree_skb in dccp_rcv_state_process if
> dccp_v6_conn_request successfully returns.
> 
> However, if IPV6_RECVPKTINFO is set on a socket, the address of the skb
> is saved to ireq->pktopts and the ref count for skb is incremented in
> dccp_v6_conn_request, so skb is still in use. Nevertheless, it gets freed
> in dccp_rcv_state_process.
> 
> Fix by calling consume_skb instead of doing goto discard and therefore
> calling __kfree_skb.
> 
> Similar fixes for TCP:
> 
> fb7e2399ec17f1004c0e0ccfd17439f8759ede01 [TCP]: skb is unexpectedly freed.
> 0aea76d35c9651d55bbaf746e7914e5f9ae5a25d tcp: SYN packets are now
> simply consumed
> 
> Signed-off-by: Andrey Konovalov <andreyknvl@...gle.com>

Applied and queued up for -stable, thanks.