Affected: Linux, Siemens SIMATIC S7-1500 TM MFP - BIOS, Siemens SIMATIC S7-1500 TM MFP - GNU/Linux subsystem

In the Linux kernel, the following vulnerability has been resolved:

gtp: Destroy device along with udp socket's netns dismantle.

gtp_newlink() links the device to a list in dev_net(dev) instead of src_net, where a udp tunnel socket is created.

Even when src_net is removed, the device stays alive on dev_net(dev). Then, removing src_net triggers the splat below. [0]

In this example, gtp0 is created in ns2, and the udp socket is created in ns1.

ip netns add ns1 ip netns add ns2 ip -n ns1 link add netns ns2 name gtp0 type gtp role sgsn ip netns del ns1

Let's link the device to the socket's netns instead.

Now, gtp_net_exit_batch_rtnl() needs another netdev iteration to remove all gtp devices in the netns.

[0]: ref_tracker: net notrefcnt@000000003d6e7d05 has 1/2 users at sk_alloc (./include/net/net_namespace.h:345 net/core/sock.c:2236) inet_create (net/ipv4/af_inet.c:326 net/ipv4/af_inet.c:252) __sock_create (net/socket.c:1558) udp_sock_create4 (net/ipv4/udp_tunnel_core.c:18) gtp_create_sock (./include/net/udp_tunnel.h:59 drivers/net/gtp.c:1423) gtp_create_sockets (drivers/net/gtp.c:1447) gtp_newlink (drivers/net/gtp.c:1507) rtnl_newlink (net/core/rtnetlink.c:3786 net/core/rtnetlink.c:3897 net/core/rtnetlink.c:4012) rtnetlink_rcv_msg (net/core/rtnetlink.c:6922) netlink_rcv_skb (net/netlink/af_netlink.c:2542) netlink_unicast (net/netlink/af_netlink.c:1321 net/netlink/af_netlink.c:1347) netlink_sendmsg (net/…