CVE-2025-38306 fs/fhandle.c: fix a race in call of has_locked_children()

In the Linux kernel, the following vulnerability has been resolved: fs/fhandle.c: fix a race in call of haslockedchildren maydecodefh is calling haslockedchildren while holding no locks. That's an oopsable race... The rest of the callers are safe since they are holding namespacesem and are...