netdev - Re: [PATCH] ipv4: ip_check_defrag should correctly check return value of skb_copy

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Date:	Tue, 17 Feb 2015 07:55:29 -0800
From:	Eric Dumazet <eric.dumazet@...il.com>
To:	Alexander Drozdov <al.drozdov@...il.com>,
	Johannes Berg <johannes.berg@...el.com>
Cc:	"David S. Miller" <davem@...emloft.net>,
	Alexey Kuznetsov <kuznet@....inr.ac.ru>,
	James Morris <jmorris@...ei.org>,
	Hideaki YOSHIFUJI <yoshfuji@...ux-ipv6.org>,
	Patrick McHardy <kaber@...sh.net>, netdev@...r.kernel.org,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH] ipv4: ip_check_defrag should correctly check return
 value of skb_copy_bits

On Tue, 2015-02-17 at 13:33 +0300, Alexander Drozdov wrote:
> skb_copy_bits() returns zero on success and negative value on error,
> so it is needed to invert the condition in ip_check_defrag().
> 
> Fixes: 1bf3751ec90c ("ipv4: ip_check_defrag must not modify skb before unsharing")
> Signed-off-by: Alexander Drozdov <al.drozdov@...il.com>
> ---
>  net/ipv4/ip_fragment.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/net/ipv4/ip_fragment.c b/net/ipv4/ip_fragment.c
> index e5b6d0d..2c8d98e 100644
> --- a/net/ipv4/ip_fragment.c
> +++ b/net/ipv4/ip_fragment.c
> @@ -664,7 +664,7 @@ struct sk_buff *ip_check_defrag(struct sk_buff *skb, u32 user)
>  	if (skb->protocol != htons(ETH_P_IP))
>  		return skb;
>  
> -	if (!skb_copy_bits(skb, 0, &iph, sizeof(iph)))
> +	if (skb_copy_bits(skb, 0, &iph, sizeof(iph)) < 0)
>  		return skb;
>  
>  	if (iph.ihl < 5 || iph.version != 4)

Thanks, I wonder how this was not found/fixed earlier.

Acked-by: Eric Dumazet <edumazet@...gle.com>
Cc: Johannes Berg <johannes.berg@...el.com>

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