CVE-2023-52638 Information

Description

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]

Reference

https://git.kernel.org/stable/c/03358aba991668d3bb2c65b3c82aa32c36851170 https://git.kernel.org/stable/c/aedda066d717a0b4335d7e0a00b2e3a61e40afcf https://git.kernel.org/stable/c/26dfe112ec2e95fe0099681f6aec33da13c2dd8e https://git.kernel.org/stable/c/559b6322f9480bff68cfa98d108991e945a4f284 https://git.kernel.org/stable/c/6cdedc18ba7b9dacc36466e27e3267d201948c8d