CVE-2022-50405

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

net/tunnel: wait until all sk_user_data reader finish before releasing the sock

There is a race condition in vxlan that when deleting a vxlan device

during receiving packets, there is a possibility that the sock is

released after getting vxlan_sock vs from sk_user_data. Then in

later vxlan_ecn_decapsulate(), vxlan_get_sk_family() we will got

NULL pointer dereference. e.g.

#0 [ffffa25ec6978a38] machine_kexec at ffffffff8c669757

#1 [ffffa25ec6978a90] __crash_kexec at ffffffff8c7c0a4d

#2 [ffffa25ec6978b58] crash_kexec at ffffffff8c7c1c48

#3 [ffffa25ec6978b60] oops_end at ffffffff8c627f2b

#4 [ffffa25ec6978b80] page_fault_oops at ffffffff8c678fcb

#5 [ffffa25ec6978bd8] exc_page_fault at ffffffff8d109542

#6 [ffffa25ec6978c00] asm_exc_page_fault at ffffffff8d200b62

[exception RIP: vxlan_ecn_decapsulate+0x3b]

RIP: ffffffffc1014e7b RSP: ffffa25ec6978cb0 RFLAGS: 00010246

RAX: 0000000000000008 RBX: ffff8aa000888000 RCX: 0000000000000000

RDX: 000000000000000e RSI: ffff8a9fc7ab803e RDI: ffff8a9fd1168700

RBP: ffff8a9fc7ab803e R8: 0000000000700000 R9: 00000000000010ae

R10: ffff8a9fcb748980 R11: 0000000000000000 R12: ffff8a9fd1168700

R13: ffff8aa000888000 R14: 00000000002a0000 R15: 00000000000010ae

ORIG_RAX: ffffffffffffffff CS: 0010 SS: 0018

#7 [ffffa25ec6978ce8] vxlan_rcv at ffffffffc10189cd [vxlan]

#8 [ffffa25ec6978d90] udp_queue_rcv_one_skb at ffffffff8cfb6507

#9 [ffffa25ec6978dc0] udp_unicast_rcv_skb at ffffffff8cfb6e45

#10 [ffffa25ec6978dc8] __udp4_lib_rcv at ffffffff8cfb8807

#11 [ffffa25ec6978e20] ip_protocol_deliver_rcu at ffffffff8cf76951

#12 [ffffa25ec6978e48] ip_local_deliver at ffffffff8cf76bde

#13 [ffffa25ec6978ea0] __netif_receive_skb_one_core at ffffffff8cecde9b

#14 [ffffa25ec6978ec8] process_backlog at ffffffff8cece139

#15 [ffffa25ec6978f00] __napi_poll at ffffffff8ceced1a

#16 [ffffa25ec6978f28] net_rx_action at ffffffff8cecf1f3

#17 [ffffa25ec6978fa0] __softirqentry_text_start at ffffffff8d4000ca

#18 [ffffa25ec6978ff0] do_softirq at ffffffff8c6fbdc3

Reproducer: https://github.com/Mellanox/ovs-tests/blob/master/test-ovs-vxlan-remove-tunnel-during-traffic.sh

Fix this by waiting for all sk_user_data reader to finish before

releasing the sock.