Bug 2414464 (CVE-2025-40139)

Summary: CVE-2025-40139 kernel: smc: Use __sk_dst_get() and dst_dev_rcu() in in smc_clc_prfx_set()
Product: [Other] Security Response Reporter: OSIDB Bzimport <bzimport>
Component: vulnerabilityAssignee: Product Security DevOps Team <prodsec-dev>
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Version: unspecifiedKeywords: Security
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OS: Linux   
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Description OSIDB Bzimport 2025-11-12 11:01:22 UTC 
In the Linux kernel, the following vulnerability has been resolved:

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

smc_clc_prfx_set() is called during connect() and not under RCU
nor RTNL.

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

Let's use __sk_dst_get() and dev_dst_rcu() under rcu_read_lock()
after kernel_getsockname().

Note that the returned value of smc_clc_prfx_set() is not used
in the caller.

While at it, we change the 1st arg of smc_clc_prfx_set[46]_rcu()
not to touch dst there.
Comment 1 Alexander B 2025-11-13 17:08:48 UTC 
Upstream advisory:
https://lore.kernel.org/linux-cve-announce/2025111255-CVE-2025-40139-a030@gregkh/T