3.6.11.1 stable review patch. If anyone has any objections, please let me know. ------------------ From: Eric Dumazet [ Upstream commit bd090dfc634ddd711a5fbd0cadc6e0ab4977bcaf ] We added support for RFC 5961 in latest kernels but TCP fails to perform exhaustive check of ACK sequence. We can update our view of peer tsval from a frame that is later discarded by tcp_ack() This makes timestamps enabled sessions vulnerable to injection of a high tsval : peers start an ACK storm, since the victim sends a dupack each time it receives an ACK from the other peer. As tcp_validate_incoming() is called before tcp_ack(), we should not peform tcp_replace_ts_recent() from it, and let callers do it at the right time. Signed-off-by: Eric Dumazet Cc: Neal Cardwell Cc: Yuchung Cheng Cc: Nandita Dukkipati Cc: H.K. Jerry Chu Cc: Romain Francoise Signed-off-by: David S. Miller --- net/ipv4/tcp_input.c | 15 ++++++++++----- 1 file changed, 10 insertions(+), 5 deletions(-) diff --git a/net/ipv4/tcp_input.c b/net/ipv4/tcp_input.c index c92c4da..7ccf80f 100644 --- a/net/ipv4/tcp_input.c +++ b/net/ipv4/tcp_input.c @@ -5340,11 +5340,6 @@ static bool tcp_validate_incoming(struct sock *sk, struct sk_buff *skb, goto discard; } - /* ts_recent update must be made after we are sure that the packet - * is in window. - */ - tcp_replace_ts_recent(tp, TCP_SKB_CB(skb)->seq); - /* step 3: check security and precedence [ignored] */ /* step 4: Check for a SYN @@ -5579,6 +5574,11 @@ step5: if (th->ack && tcp_ack(sk, skb, FLAG_SLOWPATH) < 0) goto discard; + /* ts_recent update must be made after we are sure that the packet + * is in window. + */ + tcp_replace_ts_recent(tp, TCP_SKB_CB(skb)->seq); + tcp_rcv_rtt_measure_ts(sk, skb); /* Process urgent data. */ @@ -6106,6 +6106,11 @@ int tcp_rcv_state_process(struct sock *sk, struct sk_buff *skb, } else goto discard; + /* ts_recent update must be made after we are sure that the packet + * is in window. + */ + tcp_replace_ts_recent(tp, TCP_SKB_CB(skb)->seq); + /* step 6: check the URG bit */ tcp_urg(sk, skb, th); -- 1.7.10.4 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/