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authorIlpo Järvinen <ilpo.jarvinen@helsinki.fi>2007-11-14 15:47:18 -0800
committerDavid S. Miller <davem@davemloft.net>2007-11-14 15:47:18 -0800
commit96a2d41a3e495734b63bff4e5dd0112741b93b38 (patch)
tree4190a560eabaa8dd6a78c1bf2d43515605954874 /net/ipv4
parentfb93134dfc2a6e6fbedc7c270a31da03fce88db9 (diff)
[TCP]: Make sure write_queue_from does not begin with NULL ptr
NULL ptr can be returned from tcp_write_queue_head to cached_skb and then assigned to skb if packets_out was zero. Without this, system is vulnerable to a carefully crafted ACKs which obviously is remotely triggerable. Besides, there's very little that needs to be done in sacktag if there weren't any packets outstanding, just skipping the rest doesn't hurt. Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@helsinki.fi> Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'net/ipv4')
-rw-r--r--net/ipv4/tcp_input.c5
1 files changed, 5 insertions, 0 deletions
diff --git a/net/ipv4/tcp_input.c b/net/ipv4/tcp_input.c
index 12ae9a68cda..3f126ece8eb 100644
--- a/net/ipv4/tcp_input.c
+++ b/net/ipv4/tcp_input.c
@@ -1269,6 +1269,9 @@ tcp_sacktag_write_queue(struct sock *sk, struct sk_buff *ack_skb, u32 prior_snd_
if (before(TCP_SKB_CB(ack_skb)->ack_seq, prior_snd_una - tp->max_window))
return 0;
+ if (!tp->packets_out)
+ goto out;
+
/* SACK fastpath:
* if the only SACK change is the increase of the end_seq of
* the first block then only apply that SACK block
@@ -1515,6 +1518,8 @@ tcp_sacktag_write_queue(struct sock *sk, struct sk_buff *ack_skb, u32 prior_snd_
(!tp->frto_highmark || after(tp->snd_una, tp->frto_highmark)))
tcp_update_reordering(sk, tp->fackets_out - reord, 0);
+out:
+
#if FASTRETRANS_DEBUG > 0
BUG_TRAP((int)tp->sacked_out >= 0);
BUG_TRAP((int)tp->lost_out >= 0);