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 [ … ]

Affected Software

References

• https://git.kernel.org/stable/c/2179d96ec702cc33ead02a9ce40ece599b8538c5
• https://git.kernel.org/stable/c/67a9c94317402b826fc3db32afc8f39336803d97
• https://git.kernel.org/stable/c/83bdcfbd968bcc91a0632b7b625e4a9b0cba5e0d
• https://git.kernel.org/stable/c/8aa13a86964cdec4fd969ef677c6614ff068641a
• https://git.kernel.org/stable/c/8bb1589c89e61e3b182dd546f1021928ebb5c2a6
• https://git.kernel.org/stable/c/a915379594f1e045421635c6316d8f3ffa018c58
• https://git.kernel.org/stable/c/b61d327cd3cc5ea591f3bf751dd11e034f388bb5
• https://git.kernel.org/stable/c/e7f3c9df40515a6c6b46f36c4c94cf48a043f887