net: Add default_mtu() methods to blackhole dst_ops
When an IPSEC SA is still being set up, __xfrm_lookup() will return
-EREMOTE and so ip_route_output_flow() will return a blackhole route.
This can happen in a sndmsg call, and after d33e455337ea ("net: Abstract
default MTU metric calculation behind an accessor.") this leads to a
crash in ip_append_data() because the blackhole dst_ops have no
default_mtu() method and so dst_mtu() calls a NULL pointer.
Fix this by adding default_mtu() methods (that simply return 0, matching
the old behavior) to the blackhole dst_ops.
The IPv4 part of this patch fixes a crash that I saw when using an IPSEC
VPN; the IPv6 part is untested because I don't have an IPv6 VPN, but it
looks to be needed as well.
Signed-off-by: Roland Dreier <roland@purestorage.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/net/ipv4/route.c b/net/ipv4/route.c
index 351dc4e..788a3e7 100644
--- a/net/ipv4/route.c
+++ b/net/ipv4/route.c
@@ -2707,6 +2707,11 @@
return NULL;
}
+static unsigned int ipv4_blackhole_default_mtu(const struct dst_entry *dst)
+{
+ return 0;
+}
+
static void ipv4_rt_blackhole_update_pmtu(struct dst_entry *dst, u32 mtu)
{
}
@@ -2716,6 +2721,7 @@
.protocol = cpu_to_be16(ETH_P_IP),
.destroy = ipv4_dst_destroy,
.check = ipv4_blackhole_dst_check,
+ .default_mtu = ipv4_blackhole_default_mtu,
.update_pmtu = ipv4_rt_blackhole_update_pmtu,
};
diff --git a/net/ipv6/route.c b/net/ipv6/route.c
index 28a85fc..1c29f95 100644
--- a/net/ipv6/route.c
+++ b/net/ipv6/route.c
@@ -113,6 +113,11 @@
.local_out = __ip6_local_out,
};
+static unsigned int ip6_blackhole_default_mtu(const struct dst_entry *dst)
+{
+ return 0;
+}
+
static void ip6_rt_blackhole_update_pmtu(struct dst_entry *dst, u32 mtu)
{
}
@@ -122,6 +127,7 @@
.protocol = cpu_to_be16(ETH_P_IPV6),
.destroy = ip6_dst_destroy,
.check = ip6_dst_check,
+ .default_mtu = ip6_blackhole_default_mtu,
.update_pmtu = ip6_rt_blackhole_update_pmtu,
};