CVE-2023-53517

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

tipc: do not update mtu if msg_max is too small in mtu negotiation

When doing link mtu negotiation, a malicious peer may send Activate msg with a very small mtu, e.g. 4 in Shuangs testing, without checking for the minimum mtu, l->mtu will be set to 4 in tipc_link_proto_rcv(), then n->links[bearer_id].mtu is set to 4294967228, which is a overflow of 4 - INT_H_SIZE - EMSG_OVERHEAD in tipc_link_mss().

With tipc_link.mtu = 4, tipc_link_xmit() kept printing the warning:

tipc: Too large msg, purging xmit list 1 5 0 40 4! tipc: Too large msg, purging xmit list 1 15 0 60 4!

And with tipc_link_entry.mtu 4294967228, a huge skb was allocated in named_distribute(), and when purging it in tipc_link_xmit(), a crash was even caused:

general protection fault, probably for non-canonical address 0x2100001011000dd: 0000 [#1] PREEMPT SMP PTI CPU: 0 PID: 0 Comm: swapper/0 Kdump: loaded Not tainted 6.3.0.neta #19 RIP: 0010:kfree_skb_list_reason+0x7e/0x1f0 Call Trace: skb_release_data+0xf9/0x1d0 kfree_skb_reason+0x40/0x100 tipc_link_xmit+0x57a/0x740 [tipc] tipc_node_xmit+0x16c/0x5c0 [tipc] tipc_named_node_up+0x27f/0x2c0 [tipc] tipc_node_write_unlock+0x149/0x170 [tipc] tipc_rcv+0x608/0x740 [tipc] tipc_udp_recv+0xdc/0x1f0 [tipc] udp_queue_rcv_one_skb+0x33e/0x620 udp_unicast_rcv_skb.isra.72+0x75/0x90 __udp4_lib_rcv+0x56d/0xc20 ip_protocol_deliver_rcu+0x100/0x2d0

This patch fixes it by checking the new mtu against tipc_bearer_min_mtu(), and not updating mtu if it is too small.

Affected Software

References

• https://git.kernel.org/stable/c/1dd7ae5e0cf5a56e513f7ab7ab9570b7496281d2
• https://git.kernel.org/stable/c/259683001d7e879fea4b42084fb6560dd9408a7e
• https://git.kernel.org/stable/c/2bd4ff4ffb92113f8acd04dbaed83269172c24b4
• https://git.kernel.org/stable/c/56077b56cd3fb78e1c8619e29581ba25a5c55e86
• https://git.kernel.org/stable/c/575e84d90a74c0b091b3417ba763ebb237aa0a8c