netdev - Re: [net 1/1] tipc: fix skb truesize/datasize ratio control

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Message-Id: <20180208.153115.260191898373353330.davem@davemloft.net>
Date:   Thu, 08 Feb 2018 15:31:15 -0500 (EST)
From:   David Miller <davem@...emloft.net>
To:     jon.maloy@...csson.com
Cc:     netdev@...r.kernel.org,
        mohan.krishna.ghanta.krishnamurthy@...csson.com,
        tung.q.nguyen@...tech.com.au, hoang.h.le@...tech.com.au,
        canh.d.luu@...tech.com.au, ying.xue@...driver.com,
        tipc-discussion@...ts.sourceforge.net
Subject: Re: [net 1/1] tipc: fix skb truesize/datasize ratio control

From: Jon Maloy <jon.maloy@...csson.com>
Date: Thu, 8 Feb 2018 17:16:25 +0100

> From: Hoang Le <hoang.h.le@...tek.com.au>
> 
> In commit d618d09a68e4 ("tipc: enforce valid ratio between skb truesize
> and contents") we introduced a test for ensuring that the condition
> truesize/datasize <= 4 is true for a received buffer. Unfortunately this
> test has two problems.
> 
> - Because of the integer arithmetics the test
>   if (skb->truesize / buf_roundup_len(skb) > 4) will miss all
>   ratios [4 < ratio < 5], which was not the intention.
> - The buffer returned by skb_copy() inherits skb->truesize of the
>   original buffer, which doesn't help the situation at all.
> 
> In this commit, we change the ratio condition and replace skb_copy()
> with a call to skb_copy_expand() to finally get this right.
> 
> Acked-by: Jon Maloy <jon.maloy@...csson.com>
> Signed-off-by: Jon Maloy <jon.maloy@...csson.com>

Applied, thanks Jon.