CVE-2021-47309

In the Linux kernel, the following vulnerability has been resolved: net:
validate lwtstate->data before returning from skb_tunnel_info()
skb_tunnel_info() returns pointer of lwtstate->data as ip_tunnel_info type
without validation. lwtstate->data can have various types such as
mpls_iptunnel_encap, etc and these are not compatible. So skb_tunnel_info()
should validate before returning that pointer. Splat looks like: BUG:
KASAN: slab-out-of-bounds in vxlan_get_route+0x418/0x4b0 [vxlan] Read of
size 2 at addr ffff888106ec2698 by task ping/811 CPU: 1 PID: 811 Comm: ping
Not tainted 5.13.0+ #1195 Call Trace: dump_stack_lvl+0x56/0x7b
print_address_description.constprop.8.cold.13+0x13/0x2ee ?
vxlan_get_route+0x418/0x4b0 [vxlan] ? vxlan_get_route+0x418/0x4b0 [vxlan]
kasan_report.cold.14+0x83/0xdf ? vxlan_get_route+0x418/0x4b0 [vxlan]
vxlan_get_route+0x418/0x4b0 [vxlan] [ … ] vxlan_xmit_one+0x148b/0x32b0
[vxlan] [ … ] vxlan_xmit+0x25c5/0x4780 [vxlan] [ … ]
dev_hard_start_xmit+0x1ae/0x6e0 __dev_queue_xmit+0x1f39/0x31a0 [ … ]
neigh_xmit+0x2f9/0x940 mpls_xmit+0x911/0x1600 [mpls_iptunnel]
lwtunnel_xmit+0x18f/0x450 ip_finish_output2+0x867/0x2040 [ … ]