On 2019-06-17 10:03:54, Eric Dumazet wrote: > 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 <eduma...@google.com> > Reported-by: Jonathan Lemon <jonathan.le...@gmail.com> > Cc: Jonathan Looney <j...@netflix.com> > Acked-by: Neal Cardwell <ncardw...@google.com> > Cc: Yuchung Cheng <ych...@google.com> > Cc: Tyler Hicks <tyhi...@canonical.com>
As mentioned for the other sysctl patch, I've given the two sysctl patches a close review and some testing. Acked-by: Tyler Hicks <tyhi...@canonical.com> Tyler > Cc: Bruce Curtis <bru...@netflix.com> > --- > net/ipv4/tcp_timer.c | 1 + > 1 file changed, 1 insertion(+) > > diff --git a/net/ipv4/tcp_timer.c b/net/ipv4/tcp_timer.c > index > 5bad937ce779ef8dca42a26dcbb5f1d60a571c73..c801cd37cc2a9c11f2dd4b9681137755e501a538 > 100644 > --- a/net/ipv4/tcp_timer.c > +++ b/net/ipv4/tcp_timer.c > @@ -155,6 +155,7 @@ static void tcp_mtu_probing(struct inet_connection_sock > *icsk, struct sock *sk) > 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); > -- > 2.22.0.410.gd8fdbe21b5-goog >
