netdev - Re: [Patch net] net: drop skb on failure in ip_check

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Message-ID: <4d4d6572-b6ec-edaf-d88e-5097d1b4cb1c@gmail.com>
Date:   Thu, 1 Nov 2018 12:08:40 -0700
From:   Eric Dumazet <eric.dumazet@...il.com>
To:     Cong Wang <xiyou.wangcong@...il.com>, netdev@...r.kernel.org
Cc:     Eric Dumazet <edumazet@...gle.com>
Subject: Re: [Patch net] net: drop skb on failure in ip_check_defrag()



On 11/01/2018 12:02 PM, Cong Wang wrote:
> Most callers of pskb_trim_rcsum() simply drop the skb when
> it fails, however, ip_check_defrag() still continues to pass
> the skb up to stack. This is suspicious.
> 
> In ip_check_defrag(), after we learn the skb is an IP fragment,
> passing the skb to callers makes no sense, because callers expect
> fragments are defrag'ed on success. So, dropping the skb when we
> can't defrag it is reasonable.
> 
> Note, prior to commit 88078d98d1bb, this is not a big problem as
> checksum will be fixed up anyway. After it, the checksum is not
> correct on failure.
> 
> Found this during code review.
> 
> Fixes: 88078d98d1bb ("net: pskb_trim_rcsum() and CHECKSUM_COMPLETE are friends")
> Cc: Eric Dumazet <edumazet@...gle.com>
> Signed-off-by: Cong Wang <xiyou.wangcong@...il.com>

Thanks Cong !

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