netdev - Re: [PATCH net-stable] ipv4: keep skb->dst around in presence of IP options

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Date:   Tue, 21 Mar 2017 11:25:29 +0000
From:   Ben Hutchings <ben@...adent.org.uk>
To:     Eric Dumazet <eric.dumazet@...il.com>
Cc:     Anarcheuz Fritz <anarcheuz@...il.com>, davem@...emloft.net,
        security@...nel.org, netdev@...r.kernel.org
Subject: Re: [PATCH net-stable] ipv4: keep skb->dst around in presence of IP
 options

On Mon, 2017-03-20 at 21:23 -0700, Eric Dumazet wrote:
> From: Eric Dumazet <edumazet@...gle.com>
> 
> Upstream commit 34b2cef20f19c87999fff3da4071e66937db9644
> ("ipv4: keep skb->dst around in presence of IP options") incorrectly
> root caused commit d826eb14ecef ("ipv4: PKTINFO doesnt need dst
> reference") as bug origin.
> 
> This patch should fix the issue for 3.2.xx stable kernels, since IPv4
> options seem to get more traction these days, after years of oblivion
> ;)
> 
> Fixes: f84af32cbca70 ("net: ip_queue_rcv_skb() helper"))
> Signed-off-by: Eric Dumazet <edumazet@...gle.com>
> Reported-by: Anarcheuz Fritz <anarcheuz@...il.com>
> ---
> 
> This is a backport for 3.2 kernels.

Added to the queue, thanks.

Ben.

> diff --git a/net/ipv4/ip_sockglue.c b/net/ipv4/ip_sockglue.c
> index b3648bbef0da..a6e1eeb02267 100644
> --- a/net/ipv4/ip_sockglue.c
> +++ b/net/ipv4/ip_sockglue.c
> @@ -1009,7 +1009,8 @@ e_inval:
>   */
>  int ip_queue_rcv_skb(struct sock *sk, struct sk_buff *skb)
>  {
> -	if (!(inet_sk(sk)->cmsg_flags & IP_CMSG_PKTINFO))
> +	if (!(inet_sk(sk)->cmsg_flags & IP_CMSG_PKTINFO) &&
> +	    !IPCB(skb)->opt.optlen)
>  		skb_dst_drop(skb);
>  	return sock_queue_rcv_skb(sk, skb);
>  }
> 
> 
-- 
Ben Hutchings
Power corrupts.  Absolute power is kind of neat.
                           - John Lehman, Secretary of the US Navy
1981-1987


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