From a0d7e098d148e648f72b2dff5173170b59a41aa0 Mon Sep 17 00:00:00 2001 From: "David S. Miller" Date: Wed, 10 Nov 2010 21:35:37 -0800 Subject: [PATCH] tcp: Increase TCP_MAXSEG socket option minimum. commit 7a1abd08d52fdeddb3e9a5a33f2f15cc6a5674d2 upstream. As noted by Steve Chen, since commit f5fff5dc8a7a3f395b0525c02ba92c95d42b7390 ("tcp: advertise MSS requested by user") we can end up with a situation where tcp_select_initial_window() does a divide by a zero (or even negative) mss value. The problem is that sometimes we effectively subtract TCPOLEN_TSTAMP_ALIGNED and/or TCPOLEN_MD5SIG_ALIGNED from the mss. Fix this by increasing the minimum from 8 to 64. Reported-by: Steve Chen Signed-off-by: David S. Miller Cc: Moritz Muehlenhoff Signed-off-by: Greg Kroah-Hartman --- net/ipv4/tcp.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/net/ipv4/tcp.c b/net/ipv4/tcp.c index dc2caaf5e162..87538ed935b3 100644 --- a/net/ipv4/tcp.c +++ b/net/ipv4/tcp.c @@ -2033,7 +2033,7 @@ static int do_tcp_setsockopt(struct sock *sk, int level, /* Values greater than interface MTU won't take effect. However * at the point when this call is done we typically don't yet * know which interface is going to be used */ - if (val < 8 || val > MAX_TCP_WINDOW) { + if (val < 64 || val > MAX_TCP_WINDOW) { err = -EINVAL; break; } -- 2.11.4.GIT