CVE-2024-56654: Undefined Security Weakness

In the Linux kernel, the following vulnerability has been resolved:

Bluetooth: hci_event: Fix using rcu_read_(un)lock while iterating

The usage of rcu_read_(un)lock while inside list_for_each_entry_rcu is not safe since for the most part entries fetched this way shall be treated as rcu_dereference:

Note that the value returned by rcu_dereference() is valid only within the enclosing RCU read-side critical section [1]_. For example, the following is **not** legal::

rcu_read_lock(); p = rcu_dereference(head.next); rcu_read_unlock(); x = p->address; /* BUG!!! */ rcu_read_lock(); y = p->data; /* BUG!!! */ rcu_read_unlock();