| From | Paul Gortmaker <> | Subject | [34-longterm 138/209] tcp: Increase TCP_MAXSEG socket option minimum. | Date | Thu, 14 Apr 2011 13:54:56 -0400 |
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From: David S. Miller <davem@davemloft.net>
===================================================================== | This is a commit scheduled for the next v2.6.34 longterm release. | | If you see a problem with using this for longterm, please comment.| =====================================================================
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> Signed-off-by: Paul Gortmaker <paul.gortmaker@windriver.com> --- net/ipv4/tcp.c | 2 +- 1 files changed, 1 insertions(+), 1 deletions(-)
diff --git a/net/ipv4/tcp.c b/net/ipv4/tcp.c index 68cd299..5ad716b 100644 --- a/net/ipv4/tcp.c +++ b/net/ipv4/tcp.c @@ -2234,7 +2234,7 @@ 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; } -- 1.7.4.4
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