CVE-2022-49087

/// Technical description

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

rxrpc: fix a race in rxrpc_exit_net()

Current code can lead to the following race:

CPU0 CPU1

rxrpc_exit_net()

rxrpc_peer_keepalive_worker()

if (rxnet->live)

rxnet->live = false;

del_timer_sync(&rxnet->peer_keepalive_timer);

timer_reduce(&rxnet->peer_keepalive_timer, jiffies + delay);

cancel_work_sync(&rxnet->peer_keepalive_work);

rxrpc_exit_net() exits while peer_keepalive_timer is still armed,

leading to use-after-free.

syzbot report was:

ODEBUG: free active (active state 0) object type: timer_list hint: rxrpc_peer_keepalive_timeout+0x0/0xb0

WARNING: CPU: 0 PID: 3660 at lib/debugobjects.c:505 debug_print_object+0x16e/0x250 lib/debugobjects.c:505

Modules linked in:

CPU: 0 PID: 3660 Comm: kw

/// Remediation

Check the references section for vendor advisories, patches, and mitigation guidance. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.

/// References