CVE-2025-40139

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.