net: provide default_advmss() methods to blackhole dst_ops

Commit 0dbaee3b37e118a (net: Abstract default ADVMSS behind an
accessor.) introduced a possible crash in tcp_connect_init(), when
dst->default_advmss() is called from dst_metric_advmss()

Reported-by: George Spelvin <linux@horizon.com>
Signed-off-by: Eric Dumazet <eric.dumazet@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

2 files changed, 2 insertions, 0 deletions

diff --git a/net/ipv4/route.c b/net/ipv4/route.c
index 788a3e74834e..6ed6603c2f6d 100644
--- a/net/ipv4/route.c
+++ b/net/ipv4/route.c
@@ -2722,6 +2722,7 @@ static struct dst_ops ipv4_dst_blackhole_ops = {
         .destroy                =       ipv4_dst_destroy,
         .check                  =       ipv4_blackhole_dst_check,
         .default_mtu            =       ipv4_blackhole_default_mtu,
+        .default_advmss         =       ipv4_default_advmss,
         .update_pmtu            =       ipv4_rt_blackhole_update_pmtu,
 };
 
diff --git a/net/ipv6/route.c b/net/ipv6/route.c
index 1c29f95695de..a998db6e7895 100644
--- a/net/ipv6/route.c
+++ b/net/ipv6/route.c
@@ -128,6 +128,7 @@ static struct dst_ops ip6_dst_blackhole_ops = {
         .destroy                =       ip6_dst_destroy,
         .check                  =       ip6_dst_check,
         .default_mtu            =       ip6_blackhole_default_mtu,
+        .default_advmss         =       ip6_default_advmss,
         .update_pmtu            =       ip6_rt_blackhole_update_pmtu,
 };