3.16.69-rc1 review patch. If anyone has any objections, please let me know.
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From: Eric Dumazet edumazet@google.com
commit 967c05aee439e6e5d7d805e195b3a20ef5c433d6 upstream.
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 Signed-off-by: David S. Miller davem@davemloft.net [Salvatore Bonaccorso: Backport for context changes in 4.9.168] [bwh: Backported to 3.16: The sysctl is global] Signed-off-by: Ben Hutchings ben@decadent.org.uk --- net/ipv4/tcp_timer.c | 1 + 1 file changed, 1 insertion(+)
--- a/net/ipv4/tcp_timer.c +++ b/net/ipv4/tcp_timer.c @@ -113,6 +113,7 @@ static void tcp_mtu_probing(struct inet_ mss = tcp_mtu_to_mss(sk, icsk->icsk_mtup.search_low) >> 1; mss = min(sysctl_tcp_base_mss, mss); mss = max(mss, 68 - tp->tcp_header_len); + mss = max(mss, sysctl_tcp_min_snd_mss); icsk->icsk_mtup.search_low = tcp_mss_to_mtu(sk, mss); tcp_sync_mss(sk, icsk->icsk_pmtu_cookie); }