Re: [PATCH] ipv4: ip_check_defrag should correctly check return value of skb_copy_bits

From: Eric Dumazet
Date: Tue Feb 17 2015 - 10:55:40 EST


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@xxxxxxxxx>
> ---
> 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@xxxxxxxxxx>
Cc: Johannes Berg <johannes.berg@xxxxxxxxx>

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