[PATCH 5.11 086/122] net: sit: Unregister catch-all devices

Greg Kroah-Hartman
2021-04-19T13:13:59Z

From: Hristo Venev <hristo@venev.name>

commit 610f8c0fc8d46e0933955ce13af3d64484a4630a upstream.

A sit interface created without a local or a remote address is linked
into the `sit_net::tunnels_wc` list of its original namespace. When
deleting a network namespace, delete the devices that have been moved.

The following script triggers a null pointer dereference if devices
linked in a deleted `sit_net` remain:

for i in `seq 1 30`; do
ip netns add ns-test
ip netns exec ns-test ip link add dev veth0 type veth peer veth1
ip netns exec ns-test ip link add dev sit$i type sit dev veth0
ip netns exec ns-test ip link set dev sit$i netns $$
ip netns del ns-test
done
for i in `seq 1 30`; do
ip link del dev sit$i
done

Fixes: 5e6700b3bf98f ("sit: add support of x-netns")
Signed-off-by: Hristo Venev <hristo@venev.name>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
net/ipv6/sit.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)

--- a/net/ipv6/sit.c
+++ b/net/ipv6/sit.c
@@ -1867,9 +1867,9 @@ static void __net_exit sit_destroy_tunne
if (dev->rtnl_link_ops == &sit_link_ops)
unregister_netdevice_queue(dev, head);

- for (prio = 1; prio < 4; prio++) {
+ for (prio = 0; prio < 4; prio++) {
int h;
- for (h = 0; h < IP6_SIT_HASH_SIZE; h++) {
+ for (h = 0; h < (prio ? IP6_SIT_HASH_SIZE : 1); h++) {
struct ip_tunnel *t;

t = rtnl_dereference(sitn->tunnels[prio][h]);