Bug 2414482 (CVE-2025-40168)

Summary: CVE-2025-40168 kernel: smc: Use __sk_dst_get() and dst_dev_rcu() in smc_clc_prfx_match()
Product: [Other] Security Response Reporter: OSIDB Bzimport <bzimport>
Component: vulnerabilityAssignee: Product Security DevOps Team <prodsec-dev>
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Priority: medium    
Version: unspecifiedKeywords: Security
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OS: Linux   
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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.
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Description OSIDB Bzimport 2025-11-12 11:02:38 UTC 
In the Linux kernel, the following vulnerability has been resolved:

smc: Use __sk_dst_get() and dst_dev_rcu() in smc_clc_prfx_match().

smc_clc_prfx_match() is called from smc_listen_work() and
not under RCU nor RTNL.

Using sk_dst_get(sk)->dev could trigger UAF.

Let's use __sk_dst_get() and dst_dev_rcu().

Note that the returned value of smc_clc_prfx_match() is not
used in the caller.
Comment 1 Alexander B 2025-11-13 15:48:15 UTC 
Upstream advisory:
https://lore.kernel.org/linux-cve-announce/2025111256-CVE-2025-40168-bdd5@gregkh/T