CVE-2021-4454 can: j1939: fix errant WARN_ON_ONCE in j1939_session_deactivate

In the Linux kernel, the following vulnerability has been resolved: can: j1939: fix errant WARNONONCE in j1939sessiondeactivate The conclusion "j1939sessiondeactivate should be called with a session ref-count of at least 2" is incorrect. In some concurrent scenarios, j1939sessiondeactivate can be...