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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: 8a29111c7c ("net: gro: allow to build full sized skb")
Reported-by: Christoph Paasch <christoph.paasch@uclouvain.be>
Reported-by: Jerry Chu <hkchu@google.com>
Reported-by: Sander Eikelenboom <linux@eikelenboom.it>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: Eric Dumazet <edumazet@google.com>
Tested-by: Sander Eikelenboom <linux@eikelenboom.it>
Tested-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Herbert Xu 2013-11-21 11:10:04 -08:00 committed by David S. Miller
parent 91398a0992
commit 9d8506cc2d
1 changed files with 50 additions and 25 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

75
net/core/skbuff.c
View File

@ -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;