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authorIlpo Järvinen <ilpo.jarvinen@helsinki.fi>2007-11-14 15:47:18 -0800
committerGreg Kroah-Hartman <gregkh@suse.de>2007-11-16 10:26:42 -0800
commit1ca9e250e9f8675dc1db7fcd1cee8c0bf0bfc071 (patch)
tree54a318d68306063ffca50510ec4c5339a5f2edc2
parent5ef016ad9ba96a77a7249a2bd8d3196af5bfd920 (diff)
TCP: Make sure write_queue_from does not begin with NULL ptr (CVE-2007-5501)
patch 96a2d41a3e495734b63bff4e5dd0112741b93b38 in mainline. 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> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
-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 e33fb3d0b8cc..2e1d8e75f4dd 100644
--- a/net/ipv4/tcp_input.c
+++ b/net/ipv4/tcp_input.c
@@ -994,6 +994,9 @@ 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
@@ -1262,6 +1265,8 @@ 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 + 1) - reord), 0);
+out:
+
#if FASTRETRANS_DEBUG > 0
BUG_TRAP((int)tp->sacked_out >= 0);
BUG_TRAP((int)tp->lost_out >= 0);