| From 7a1abd08d52fdeddb3e9a5a33f2f15cc6a5674d2 Mon Sep 17 00:00:00 2001 |
| From: David S. Miller <davem@davemloft.net> |
| Date: Wed, 10 Nov 2010 21:35:37 -0800 |
| Subject: tcp: Increase TCP_MAXSEG socket option minimum. |
| |
| From: David S. Miller <davem@davemloft.net> |
| |
| 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 <schen@mvista.com> |
| Signed-off-by: David S. Miller <davem@davemloft.net> |
| Cc: Moritz Muehlenhoff <jmm@debian.org> |
| Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de> |
| |
| --- |
| net/ipv4/tcp.c | 2 +- |
| 1 file changed, 1 insertion(+), 1 deletion(-) |
| |
| --- a/net/ipv4/tcp.c |
| +++ b/net/ipv4/tcp.c |
| @@ -2117,7 +2117,7 @@ static int do_tcp_setsockopt(struct sock |
| /* 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; |
| } |
