netdev - Re: [3/3] gso: Handle malicious GRO packets without crashing

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Message-ID: <527BE659.9060702@cogentembedded.com>
Date:	Thu, 07 Nov 2013 22:13:29 +0300
From:	Sergei Shtylyov <sergei.shtylyov@...entembedded.com>
To:	Herbert Xu <herbert@...dor.apana.org.au>,
	Eric Dumazet <eric.dumazet@...il.com>
CC:	Ben Hutchings <bhutchings@...arflare.com>,
	David Miller <davem@...emloft.net>,
	christoph.paasch@...ouvain.be, netdev@...r.kernel.org,
	hkchu@...gle.com, mwdalton@...gle.com
Subject: Re: [3/3] gso: Handle malicious GRO packets without crashing

Hello.

On 11/07/2013 10:08 AM, Herbert Xu wrote:

> As virtio_net can now generate GRO frag_list packets without
> sufficient verification, we need to handle malicious GRO packets
> thrown at us.

> This patch converts to affected BUG_ONs in skb_segment to rate-
> limited warnings.

> Signed-off-by: Herbert Xu <herbert@...dor.apana.org.au>

> diff --git a/net/core/skbuff.c b/net/core/skbuff.c
> index bcc3f1c..fb1106d 100644
> --- a/net/core/skbuff.c
> +++ b/net/core/skbuff.c
> @@ -2881,7 +2881,15 @@ struct sk_buff *skb_segment(struct sk_buff *skb, netdev_features_t features)
>   			while (tail->next)
>   				tail = tail->next;
>
> -			BUG_ON(fskb && tail->len != len + doffset);
> +			if (fskb && tail->len != len + doffset) {
> +				net_warn_ratelimited(
> +					"skb_segment: "
> +					"illegal GSO fragment: %u %u\n",

    Don't break up the message -- chekpatch.pl should allow that...

> @@ -2929,7 +2937,15 @@ struct sk_buff *skb_segment(struct sk_buff *skb, netdev_features_t features)
>   		if (pos < offset + len) {
>   			struct sk_buff *fskb2 = fskb;
>
> -			BUG_ON(pos + fskb->len != offset + len);
> +			if (pos + fskb->len != offset + len) {
> +				net_warn_ratelimited(
> +					"skb_segment: "
> +					"illegal GSO trailer: %u %u\n",

    Same here.

WBR, Sergei

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