From 9d8506cc2d7ea1f911c72c100193a3677f6668c3 Mon Sep 17 00:00:00 2001 From: Herbert Xu Date: Thu, 21 Nov 2013 11:10:04 -0800 Subject: [PATCH] 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 in two ways. For completely non-linear frag_list entries, we simply continue to iterate over the frag_list frags once we exhaust the normal frags. For frag_list entries with linear parts, we call pskb_trim on the first part of the frag_list skb, and then process the rest of the frags in the usual way. This patch also kills a chunk of dead frag_list code that has obviously never ever been run since it ends up generating a bogus GSO-segmented packet with a frag_list entry. Future work is planned to split super big packets into TSO ones. Fixes: 8a29111c7ca6 ("net: gro: allow to build full sized skb") Reported-by: Christoph Paasch Reported-by: Jerry Chu Reported-by: Sander Eikelenboom Signed-off-by: Herbert Xu Signed-off-by: Eric Dumazet Tested-by: Sander Eikelenboom Tested-by: Eric Dumazet Signed-off-by: David S. Miller --- net/core/skbuff.c | 75 +++++++++++++++++++++++++++++++---------------- 1 file changed, 50 insertions(+), 25 deletions(-) diff --git a/net/core/skbuff.c b/net/core/skbuff.c index 8cec1e6b844d..2718fed53d8c 100644 --- a/net/core/skbuff.c +++ b/net/core/skbuff.c @@ -2796,6 +2796,7 @@ struct sk_buff *skb_segment(struct sk_buff *skb, netdev_features_t features) struct sk_buff *segs = NULL; struct sk_buff *tail = NULL; struct sk_buff *fskb = skb_shinfo(skb)->frag_list; + skb_frag_t *skb_frag = skb_shinfo(skb)->frags; unsigned int mss = skb_shinfo(skb)->gso_size; unsigned int doffset = skb->data - skb_mac_header(skb); unsigned int offset = doffset; @@ -2835,16 +2836,38 @@ struct sk_buff *skb_segment(struct sk_buff *skb, netdev_features_t features) if (hsize > len || !sg) hsize = len; - if (!hsize && i >= nfrags) { - BUG_ON(fskb->len != len); + if (!hsize && i >= nfrags && skb_headlen(fskb) && + (skb_headlen(fskb) == len || sg)) { + BUG_ON(skb_headlen(fskb) > len); + + i = 0; + nfrags = skb_shinfo(fskb)->nr_frags; + skb_frag = skb_shinfo(fskb)->frags; + pos += skb_headlen(fskb); + + while (pos < offset + len) { + BUG_ON(i >= nfrags); + + size = skb_frag_size(skb_frag); + if (pos + size > offset + len) + break; + + i++; + pos += size; + skb_frag++; + } - pos += len; nskb = skb_clone(fskb, GFP_ATOMIC); fskb = fskb->next; if (unlikely(!nskb)) goto err; + if (unlikely(pskb_trim(nskb, len))) { + kfree_skb(nskb); + goto err; + } + hsize = skb_end_offset(nskb); if (skb_cow_head(nskb, doffset + headroom)) { kfree_skb(nskb); @@ -2881,7 +2904,7 @@ 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) + if (nskb->len == len + doffset) goto perform_csum_check; if (!sg) { @@ -2899,8 +2922,28 @@ struct sk_buff *skb_segment(struct sk_buff *skb, netdev_features_t features) skb_shinfo(nskb)->tx_flags = skb_shinfo(skb)->tx_flags & SKBTX_SHARED_FRAG; - while (pos < offset + len && i < nfrags) { - *frag = skb_shinfo(skb)->frags[i]; + while (pos < offset + len) { + if (i >= nfrags) { + BUG_ON(skb_headlen(fskb)); + + i = 0; + nfrags = skb_shinfo(fskb)->nr_frags; + skb_frag = skb_shinfo(fskb)->frags; + + BUG_ON(!nfrags); + + fskb = fskb->next; + } + + if (unlikely(skb_shinfo(nskb)->nr_frags >= + MAX_SKB_FRAGS)) { + net_warn_ratelimited( + "skb_segment: too many frags: %u %u\n", + pos, mss); + goto err; + } + + *frag = *skb_frag; __skb_frag_ref(frag); size = skb_frag_size(frag); @@ -2913,6 +2956,7 @@ struct sk_buff *skb_segment(struct sk_buff *skb, netdev_features_t features) if (pos + size <= offset + len) { i++; + skb_frag++; pos += size; } else { skb_frag_size_sub(frag, pos + size - (offset + len)); @@ -2922,25 +2966,6 @@ struct sk_buff *skb_segment(struct sk_buff *skb, netdev_features_t features) frag++; } - if (pos < offset + len) { - struct sk_buff *fskb2 = fskb; - - BUG_ON(pos + fskb->len != offset + len); - - pos += fskb->len; - fskb = fskb->next; - - if (fskb2->next) { - fskb2 = skb_clone(fskb2, GFP_ATOMIC); - if (!fskb2) - goto err; - } else - skb_get(fskb2); - - SKB_FRAG_ASSERT(nskb); - skb_shinfo(nskb)->frag_list = fskb2; - } - skip_fraglist: nskb->data_len = len - hsize; nskb->len += nskb->data_len; -- 2.34.1