CVE-2022-49664

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

tipc: move bc link creation back to tipc_node_create

Shuang Li reported a NULL pointer dereference crash:

[] BUG: kernel NULL pointer dereference, address: 0000000000000068 [] RIP: 0010:tipc_link_is_up+0x5/0x10 [tipc] [] Call Trace: [] <IRQ> [] tipc_bcast_rcv+0xa2/0x190 [tipc] [] tipc_node_bc_rcv+0x8b/0x200 [tipc] [] tipc_rcv+0x3af/0x5b0 [tipc] [] tipc_udp_recv+0xc7/0x1e0 [tipc]

It was caused by the 'l' passed into tipc_bcast_rcv() is NULL. When it creates a node in tipc_node_check_dest(), after inserting the new node into hashtable in tipc_node_create(), it creates the bc link. However, there is a gap between this insert and bc link creation, a bc packet may come in and get the node from the hashtable then try to dereference its bc link, which is NULL.

This patch is to fix it by moving the bc link creation before inserting into the hashtable.

Note that for a preliminary node becoming "real", the bc link creation should also be called before it's rehashed, as we don't create it for preliminary nodes.

This vulnerability is rated as Moderate because exploitation requires the TIPC networking module to be actively configured, and the race condition results in a kernel crash (denial of service) without compromising system confidentiality or integrity. In standard Red Hat Enterprise Linux environments, the TIPC module is not loaded by default, restricting exposure to systems explicitly configured for TIPC cluster communication. Exploitation requires the attacker to be able to send broadcast packets to the target system while nodes are being established.

The CVSS score(s) listed for this vulnerability do not reflect the associated product's status, and are included for informational purposes to better understand the severity of this vulnerability.