3.16.69-rc1 review patch. If anyone has any objections, please let me know.
------------------ From: Eric Dumazet <[email protected]> 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 <[email protected]> Reported-by: Jonathan Lemon <[email protected]> Cc: Jonathan Looney <[email protected]> Acked-by: Neal Cardwell <[email protected]> Cc: Yuchung Cheng <[email protected]> Cc: Tyler Hicks <[email protected]> Cc: Bruce Curtis <[email protected]> Signed-off-by: David S. Miller <[email protected]> [Salvatore Bonaccorso: Backport for context changes in 4.9.168] [bwh: Backported to 3.16: The sysctl is global] Signed-off-by: Ben Hutchings <[email protected]> --- 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); }
