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[TCP]: Compute in_sacked properly when we split up a TSO frame.

Browse source 
The problem is that the SACK fragmenting code may incorrectly call
tcp_fragment() with a length larger than the skb->len.  This happens
when the skb on the transmit queue completely falls to the LHS of the
SACK.

And add a BUG() check to tcp_fragment() so we can spot this kind of
error more quickly in the future.

Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Herbert Xu 2005-09-14 20:50:35 -07:00 committed by David S. Miller
parent 1619cca292
commit 3c05d92ed4
2 changed files with 11 additions and 7 deletions
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16
net/ipv4/tcp_input.c
View file

@ -979,14 +979,19 @@ tcp_sacktag_write_queue(struct sock *sk, struct sk_buff *ack_skb, u32 prior_snd_
if (!before(TCP_SKB_CB(skb)->seq, end_seq))
break;
in_sack = !after(start_seq, TCP_SKB_CB(skb)->seq) &&
!before(end_seq, TCP_SKB_CB(skb)->end_seq);
pcount = tcp_skb_pcount(skb);
if (pcount > 1 &&
(after(start_seq, TCP_SKB_CB(skb)->seq) ||
before(end_seq, TCP_SKB_CB(skb)->end_seq))) {
if (pcount > 1 && !in_sack &&
after(TCP_SKB_CB(skb)->end_seq, start_seq)) {
unsigned int pkt_len;
if (after(start_seq, TCP_SKB_CB(skb)->seq))
in_sack = !after(start_seq,
TCP_SKB_CB(skb)->seq);
if (!in_sack)
pkt_len = (start_seq -
TCP_SKB_CB(skb)->seq);
else
@ -999,9 +1004,6 @@ tcp_sacktag_write_queue(struct sock *sk, struct sk_buff *ack_skb, u32 prior_snd_
fack_count += pcount;
in_sack = !after(start_seq, TCP_SKB_CB(skb)->seq) &&
!before(end_seq, TCP_SKB_CB(skb)->end_seq);
sacked = TCP_SKB_CB(skb)->sacked;
/* Account D-SACK for retransmitted packet. */

2
net/ipv4/tcp_output.c
View file

@ -435,6 +435,8 @@ int tcp_fragment(struct sock *sk, struct sk_buff *skb, u32 len, unsigned int mss
int nsize, old_factor;
u16 flags;
BUG_ON(len >= skb->len);
nsize = skb_headlen(skb) - len;
if (nsize < 0)
nsize = 0;