37 lines
1.3 KiB
Diff
37 lines
1.3 KiB
Diff
From: Eric Dumazet <edumazet@google.com>
|
|
Date: Mon, 17 Jun 2019 10:03:54 -0700
|
|
Subject: [PATCH net 4/4] tcp: enforce tcp_min_snd_mss in tcp_mtu_probing()
|
|
Origin: https://patchwork.ozlabs.org/patch/1117158/
|
|
|
|
If mtu probing is enabled tcp_mtu_probing() could very well end up
|
|
with a too small MSS.
|
|
|
|
Use the new sysctl tcp_min_snd_mss to make sure MSS search
|
|
is performed in an acceptable range.
|
|
|
|
CVE-2019-11479 -- tcp mss hardcoded to 48
|
|
|
|
Signed-off-by: Eric Dumazet <edumazet@google.com>
|
|
Reported-by: Jonathan Lemon <jonathan.lemon@gmail.com>
|
|
Cc: Jonathan Looney <jtl@netflix.com>
|
|
Acked-by: Neal Cardwell <ncardwell@google.com>
|
|
Cc: Yuchung Cheng <ycheng@google.com>
|
|
Cc: Tyler Hicks <tyhicks@canonical.com>
|
|
Cc: Bruce Curtis <brucec@netflix.com>
|
|
Acked-by: Jonathan Lemon <jonathan.lemon@gmail.com>
|
|
Acked-by: Tyler Hicks <tyhicks@canonical.com>
|
|
---
|
|
net/ipv4/tcp_timer.c | 1 +
|
|
1 file changed, 1 insertion(+)
|
|
|
|
--- a/net/ipv4/tcp_timer.c
|
|
+++ b/net/ipv4/tcp_timer.c
|
|
@@ -166,6 +166,7 @@ static void tcp_mtu_probing(struct inet_
|
|
mss = tcp_mtu_to_mss(sk, icsk->icsk_mtup.search_low) >> 1;
|
|
mss = min(net->ipv4.sysctl_tcp_base_mss, mss);
|
|
mss = max(mss, 68 - tcp_sk(sk)->tcp_header_len);
|
|
+ mss = max(mss, net->ipv4.sysctl_tcp_min_snd_mss);
|
|
icsk->icsk_mtup.search_low = tcp_mss_to_mtu(sk, mss);
|
|
}
|
|
tcp_sync_mss(sk, icsk->icsk_pmtu_cookie);
|