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authorEric Dumazet <eric.dumazet@gmail.com>2011-12-04 08:51:08 +0000
committerDavid S. Miller <davem@davemloft.net>2011-12-05 18:30:03 -0500
commit4fa48bf3c75069d636fc8830743c929a062e80dc (patch)
tree3fe5e488ee6ac1af1b76497a5e6281106a8b2d2e
parentcaif: Stash away hijacked skb destructor and call it later (diff)
downloadlinux-dev-4fa48bf3c75069d636fc8830743c929a062e80dc.tar.xz
linux-dev-4fa48bf3c75069d636fc8830743c929a062e80dc.zip
tcp: fix tcp_trim_head()
commit f07d960df3 (tcp: avoid frag allocation for small frames) breaked assumption in tcp stack that skb is either linear (skb->data_len == 0), or fully fragged (skb->data_len == skb->len) tcp_trim_head() made this assumption, we must fix it. Thanks to Vijay for providing a very detailed explanation. Reported-by: Vijay Subramanian <subramanian.vijay@gmail.com> Signed-off-by: Eric Dumazet <eric.dumazet@gmail.com> Signed-off-by: David S. Miller <davem@davemloft.net>
-rw-r--r--net/ipv4/tcp_output.c13
1 files changed, 8 insertions, 5 deletions
diff --git a/net/ipv4/tcp_output.c b/net/ipv4/tcp_output.c
index 50788d67bdb7..cf3068038942 100644
--- a/net/ipv4/tcp_output.c
+++ b/net/ipv4/tcp_output.c
@@ -1093,6 +1093,13 @@ static void __pskb_trim_head(struct sk_buff *skb, int len)
{
int i, k, eat;
+ eat = min_t(int, len, skb_headlen(skb));
+ if (eat) {
+ __skb_pull(skb, eat);
+ len -= eat;
+ if (!len)
+ return;
+ }
eat = len;
k = 0;
for (i = 0; i < skb_shinfo(skb)->nr_frags; i++) {
@@ -1124,11 +1131,7 @@ int tcp_trim_head(struct sock *sk, struct sk_buff *skb, u32 len)
if (skb_cloned(skb) && pskb_expand_head(skb, 0, 0, GFP_ATOMIC))
return -ENOMEM;
- /* If len == headlen, we avoid __skb_pull to preserve alignment. */
- if (unlikely(len < skb_headlen(skb)))
- __skb_pull(skb, len);
- else
- __pskb_trim_head(skb, len - skb_headlen(skb));
+ __pskb_trim_head(skb, len);
TCP_SKB_CB(skb)->seq += len;
skb->ip_summed = CHECKSUM_PARTIAL;