CVE-2026-74493

Description

In the Linux kernel, the following vulnerability has been resolved: net/smc: fix socket use-after-free during link group termination __smc_lgr_terminate() drops conns_lock after finding a connection in lgr->conns_all, but before taking a reference on its socket. The connection is embedded in the socket, and its registration reference protects it only while the connection remains in the tree. A concurrent close can unregister the connection and drop that reference, freeing the socket before the termination worker reaches sock_hold(). The race is reachable when close overlaps link group termination. Local stress testing reproduced the use-after-free and KASAN reported: BUG: KASAN: slab-use-after-free in __smc_lgr_terminate.part.0 [smc] Write of size 4 by task kworker/3:3 Workqueue: events smc_lgr_terminate_work [smc] __smc_lgr_terminate.part.0 [smc] The socket was allocated by smc_create(), freed through slab_free_after_rcu_debug(), and was followed by: refcount_t: addition on 0; use-after-free. __smc_lgr_terminate.part.0 [smc] Take the socket reference while conns_lock still protects the tree entry. The unregister path then cannot drop the last reference until termination has finished using the socket.

CVSS 3.1 breakdown

Remediation

No fixed version is recorded in the NVD data. Check the vendor advisory for the latest guidance.

References

• https://git.kernel.org/stable/c/281c103a8eaed59001ce952f231df1b07674215a
• https://git.kernel.org/stable/c/5a42f162b857019a4c10ff687dc3bcdf51831865
• https://git.kernel.org/stable/c/9fb17c95b8f0683570fca1fb2792264147af937a
• https://git.kernel.org/stable/c/bea8dc14de2d56aca749d368563e6888217710a5
• https://git.kernel.org/stable/c/f0541a775d04c88e90ba448e35ce0d743512822a
• https://git.kernel.org/stable/c/f621d6ebeebb6374342571e4ddf45fdbc420f6cd
• https://git.kernel.org/stable/c/f807a63d0d95680c34f677700da9148a07d7c78f
• https://git.kernel.org/stable/c/ff44f2df57fb5560bdc75eb977867643e764a262

Frequently asked