media: cx23885: cancel NetUP CI work before teardown

netup_ci_exit() frees a netup_ci_state while its work item,
netup_read_ci_status(), may still be pending or running on the system
workqueue. The worker obtains the state with container_of() and
dereferences it, so it must not outlive the state.

netup_ci_init() queues the initial status read, and CI GPIO interrupts
subsequently queue the same work from netup_ci_slot_status(). During
remove, cx23885_finidev() calls free_irq() before the CI device is
unregistered. free_irq() prevents further IRQ handlers from running,
but does not drain work queued previously, so the worker can run after
netup_ci_exit() frees the state.

Call cancel_work_sync() before dvb_ca_en50221_release() and kfree().

This issue was found by an in-house static analysis tool.

Fixes: c184dcd282 ("V4L/DVB (10798): Add CIMax(R) SP2 Common Interface code for NetUP Dual DVB-S2 CI card")
Cc: stable@vger.kernel.org
Assisted-by: Codex:gpt-5.6
Signed-off-by: Fan Wu <fanwu01@zju.edu.cn>
Signed-off-by: Hans Verkuil <hverkuil+cisco@kernel.org>

drivers/media/pci/cx23885/cimax2.c

@@ -528,6 +528,7 @@ void netup_ci_exit(struct cx23885_tsport *port)
 	if (NULL == state->ca.data)
 		return;
 
+	cancel_work_sync(&state->work);
 	dvb_ca_en50221_release(&state->ca);
 	kfree(state);
 }