diff mbox series

[09/11] tcp: Check for filled TCP option space before SACK

Message ID 20191213204824.2464461-10-matthieu.baerts@tessares.net
State Deferred, archived
Headers show
Series Multipath TCP part 1: Prerequisites | expand

Commit Message

Matthieu Baerts Dec. 13, 2019, 8:48 p.m. UTC 
From: Mat Martineau <mathew.j.martineau@linux.intel.com>

The SACK code would potentially add four bytes to the expected
TCP option size even if all option space was already used.

Signed-off-by: Mat Martineau <mathew.j.martineau@linux.intel.com>
Signed-off-by: Matthieu Baerts <matthieu.baerts@tessares.net>
---
 net/ipv4/tcp_output.c | 3 +++
 1 file changed, 3 insertions(+)
diff mbox series

Patch

diff --git a/net/ipv4/tcp_output.c b/net/ipv4/tcp_output.c
index 9e04d45bc0e4..710ab45badfa 100644
--- a/net/ipv4/tcp_output.c
+++ b/net/ipv4/tcp_output.c
@@ -748,6 +748,9 @@  static unsigned int tcp_established_options(struct sock *sk, struct sk_buff *skb
 		size += TCPOLEN_TSTAMP_ALIGNED;
 	}
 
+	if (size + TCPOLEN_SACK_BASE_ALIGNED >= MAX_TCP_OPTION_SPACE)
+		return size;
+
 	eff_sacks = tp->rx_opt.num_sacks + tp->rx_opt.dsack;
 	if (unlikely(eff_sacks)) {
 		const unsigned int remaining = MAX_TCP_OPTION_SPACE - size;