tcp: Increase TCP_MAXSEG socket option minimum. (7a1abd08) · Commits · 戴 / test

As noted by Steve Chen, since commit ("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>

net/ipv4/tcp.c

+1 −1

Original line number	Original line	Diff line number	Diff line
	@@ -2246,7 +2246,7 @@ static int do_tcp_setsockopt(struct sock *sk, int level,
	/* Values greater than interface MTU won't take effect. However		/* Values greater than interface MTU won't take effect. However
	* at the point when this call is done we typically don't yet		* at the point when this call is done we typically don't yet
	* know which interface is going to be used */		* know which interface is going to be used */
	if (val < 8 \|\| val > MAX_TCP_WINDOW) {		if (val < 64 \|\| val > MAX_TCP_WINDOW) {
	err = -EINVAL;		err = -EINVAL;
	break;		break;
	}		}

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