On 14.01.2026 00:28:47, Tetsuo Handa wrote:

Since j1939_session_deactivate_activate_next() in j1939_tp_rxtimer() is
called only when the timer is enabled, we need to call
j1939_session_deactivate_activate_next() if we cancelled the timer.
Otherwise, refcount for j1939_session leaks, which will later appear as

  unregister_netdevice: waiting for vcan0 to become free. Usage count = 2.

problem.

Reported-by: syzbot <redacted>
Closes: https://syzkaller.appspot.com/bug?extid=881d65229ca4f9ae8c84
Signed-off-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>

Applied to linux-can.

Thanks,
Marc

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