netdev - [2/3] gso: Handle new frag_list of frags GRO packets

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Message-ID: <20131107070647.GB31638@gondor.apana.org.au>
Date:	Thu, 7 Nov 2013 15:06:47 +0800
From:	Herbert Xu <herbert@...dor.apana.org.au>
To:	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: [2/3] gso: Handle new frag_list of frags GRO packets

Recently GRO started generating packets with frag_lists of frags.
This was not handled by GSO, thus leading to a crash.

Thankfully these packets are of a regular form and are easy to
handle.  This patch handles them by calling skb_segment for each 
frag_list entry.  The depth of recursion is limited to just one.

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

diff --git a/net/core/skbuff.c b/net/core/skbuff.c
index 88b7dc6..bcc3f1c 100644
--- a/net/core/skbuff.c
+++ b/net/core/skbuff.c
@@ -2816,8 +2816,6 @@ struct sk_buff *skb_segment(struct sk_buff *skb, netdev_features_t features)
 			hsize = len;
 
 		if (!hsize && i >= nfrags) {
-			BUG_ON(fskb->len != len);
-
 			pos += len;
 			nskb = skb_clone(fskb, GFP_ATOMIC);
 			fskb = fskb->next;
@@ -2855,8 +2853,40 @@ struct sk_buff *skb_segment(struct sk_buff *skb, netdev_features_t features)
 						 nskb->data - tnl_hlen,
 						 doffset + tnl_hlen);
 
-		if (fskb != skb_shinfo(skb)->frag_list)
-			goto perform_csum_check;
+		if (fskb != skb_shinfo(skb)->frag_list) {
+			struct sk_buff *nsegs;
+
+			if (nskb->len == len + doffset)
+				goto perform_csum_check;
+
+			SKB_FRAG_ASSERT(nskb);
+
+			__skb_pull(nskb, doffset);
+			skb_shinfo(nskb)->gso_size = mss;
+			nsegs = skb_segment(nskb, features);
+
+			err = PTR_ERR(nsegs);
+			if (IS_ERR(nsegs)) {
+				kfree(nskb);
+				goto err;
+			}
+			err = -ENOMEM;
+
+			if (segs)
+				tail->next = nsegs;
+			else
+				segs = nsegs;
+
+			tail = nsegs;
+			while (tail->next)
+				tail = tail->next;
+
+			BUG_ON(fskb && tail->len != len + doffset);
+
+			len = nskb->len;
+			kfree(nskb);
+			continue;
+		}
 
 		if (!sg) {
 			nskb->ip_summed = CHECKSUM_NONE;
-- 
Email: Herbert Xu <herbert@...dor.apana.org.au>
Home Page: http://gondor.apana.org.au/~herbert/
PGP Key: http://gondor.apana.org.au/~herbert/pubkey.txt
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