net: Add default_mtu() methods to blackhole dst_ops (ec831ea7) · Commits · 戴 / test

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 ("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>

net/ipv4/route.c

+6 −0

Original line number	Diff line number	Diff line
		@@ -2707,6 +2707,11 @@ static struct dst_entry ipv4_blackhole_dst_check(struct dst_entry dst, u32 coo
		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 @@ static struct dst_ops ipv4_dst_blackhole_ops = {
		.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,
		};

net/ipv6/route.c

+6 −0

Original line number	Diff line number	Diff line
		@@ -113,6 +113,11 @@ static struct dst_ops ip6_dst_ops_template = {
		.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 @@ static struct dst_ops ip6_dst_blackhole_ops = {
		.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,
		};

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