From 7982d5e1b350acb96aa156916c44c25ef87bb809 Mon Sep 17 00:00:00 2001 From: Philip Love Date: Wed, 27 Aug 2008 02:33:50 -0700 Subject: [PATCH] tcp: fix tcp header size miscalculation when window scale is unused The size of the TCP header is miscalculated when the window scale ends up being 0. Additionally, this can be induced by sending a SYN to a passive open port with a window scale option with value 0. Signed-off-by: Philip Love Signed-off-by: Adam Langley Signed-off-by: David S. Miller --- net/ipv4/tcp_output.c | 6 ++++-- 1 file changed, 4 insertions(+), 2 deletions(-) diff --git a/net/ipv4/tcp_output.c b/net/ipv4/tcp_output.c index a00532de2a..8165f5aa8c 100644 --- a/net/ipv4/tcp_output.c +++ b/net/ipv4/tcp_output.c @@ -468,7 +468,8 @@ static unsigned tcp_syn_options(struct sock *sk, struct sk_buff *skb, } if (likely(sysctl_tcp_window_scaling)) { opts->ws = tp->rx_opt.rcv_wscale; - size += TCPOLEN_WSCALE_ALIGNED; + if(likely(opts->ws)) + size += TCPOLEN_WSCALE_ALIGNED; } if (likely(sysctl_tcp_sack)) { opts->options |= OPTION_SACK_ADVERTISE; @@ -509,7 +510,8 @@ static unsigned tcp_synack_options(struct sock *sk, if (likely(ireq->wscale_ok)) { opts->ws = ireq->rcv_wscale; - size += TCPOLEN_WSCALE_ALIGNED; + if(likely(opts->ws)) + size += TCPOLEN_WSCALE_ALIGNED; } if (likely(doing_ts)) { opts->options |= OPTION_TS; -- 2.39.5