Commit 22c74764 authored Mar 06, 2019 by Paolo Abeni Committed by David S. Miller Mar 06, 2019

ipv4/route: fail early when inet dev is missing



If a non local multicast packet reaches ip_route_input_rcu() while
the ingress device IPv4 private data (in_dev) is NULL, we end up
doing a NULL pointer dereference in IN_DEV_MFORWARD().

Since the later call to ip_route_input_mc() is going to fail if
!in_dev, we can fail early in such scenario and avoid the dangerous
code path.

v1 -> v2:
 - clarified the commit message, no code changes

Reported-by: Tianhao Zhao <tizhao@redhat.com>
Fixes: e58e4159 ("net: Enable support for VRF with ipv4 multicast")
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
Reviewed-by: David Ahern <dsahern@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

parent f4772dee

net/ipv4/route.c

+5 −4

Original line number	Diff line number	Diff line
		@@ -2149,12 +2149,13 @@ int ip_route_input_rcu(struct sk_buff *skb, __be32 daddr, __be32 saddr,
		int our = 0;
		int err = -EINVAL;

		if (in_dev)
		if (!in_dev)
		return err;
		our = ip_check_mc_rcu(in_dev, daddr, saddr,
		ip_hdr(skb)->protocol);

		/* check l3 master if no match yet */
		if ((!in_dev \|\| !our) && netif_is_l3_slave(dev)) {
		if (!our && netif_is_l3_slave(dev)) {
		struct in_device *l3_in_dev;

		l3_in_dev = __in_dev_get_rcu(skb->dev);

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