CVE-2023-52638

In the Linux kernel, the following vulnerability has been resolved: can:
j1939: prevent deadlock by changing j1939_socks_lock to rwlock The
following 3 locks would race against each other, causing the deadlock
situation in the Syzbot bug report: - j1939_socks_lock -
active_session_list_lock - sk_session_queue_lock A reasonable fix is to
change j1939_socks_lock to an rwlock, since in the rare situations where a
write lock is required for the linked list that j1939_socks_lock is
protecting, the code does not attempt to acquire any more locks. This would
break the circular lock dependency, where, for example, the current thread
already locks j1939_socks_lock and attempts to acquire
sk_session_queue_lock, and at the same time, another thread attempts to
acquire j1939_socks_lock while holding sk_session_queue_lock. NOTE: This
patch along does not fix the unregister_netdevice bug reported by Syzbot;
instead, it solves a deadlock situation to prepare for one or more further
patches to actually fix the Syzbot bug, which appears to be a reference
counting problem within the j1939 codebase. [mkl: remove unrelated newline
change]