CVE-2025-40168

A flaw was found in the Linux kernel’s SMC (Shared Memory Communication) module: in smc_clc_prfx_match(), the function is called from smc_listen_work() without proper RCU or RTNL protection. The code previously used sk_dst_get(sk)->dev, which can lead to a use-after-free (UAF) condition if the sk’s destination is freed concurrently.

This vulnerability is rated as Moderate severity because successful exploitation requires precise timing to exploit a race condition during Shared Memory Communication (SMC) socket operations, limiting its practical impact. SMC protocol support is intended for specialized environments using RDMA or ISM devices and is not enabled or utilized by default in standard Red Hat Enterprise Linux networking configurations. Consequently, systems that do not use SMC connections are unaffected in practice.

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.

Mitigation for this issue is either not available or the currently available options don't meet the Red Hat Product Security criteria comprising ease of use and deployment, applicability to widespread installation base or stability.