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ipv4/route: fail early when inet dev is missing

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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: e58e415968 ("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>
This commit is contained in:
Paolo Abeni 2019-03-06 10:42:53 +01:00 committed by David S. Miller
parent f4772dee10
commit 22c74764aa
1 changed files with 5 additions and 4 deletions
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9
net/ipv4/route.c
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@ -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)
our = ip_check_mc_rcu(in_dev, daddr, saddr,
ip_hdr(skb)->protocol);
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);