netdev - Re: [Patch net] net: make pskb_trim_rcsum

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Message-Id: <20181031.123615.1846160214217588851.davem@davemloft.net>
Date:   Wed, 31 Oct 2018 12:36:15 -0700 (PDT)
From:   David Miller <davem@...emloft.net>
To:     xiyou.wangcong@...il.com
Cc:     netdev@...r.kernel.org, edumazet@...gle.com
Subject: Re: [Patch net] net: make pskb_trim_rcsum_slow() robust

From: Cong Wang <xiyou.wangcong@...il.com>
Date: Mon, 29 Oct 2018 17:35:15 -0700

> Most callers of pskb_trim_rcsum() simply drops the skb when
> it fails, however, ip_check_defrag() still continues to pass
> the skb up to stack. In that case, we should restore its previous
> csum if __pskb_trim() fails.
> 
> 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>

I kind of agree with Eric that we should make all callers, including
ip_check_defrag(), fail just as with any memory allocation failure.