Affected: Linux

In the Linux kernel, the following vulnerability has been resolved:

media: chips-media: wave5: Fix device cleanup order to prevent kernel panic

Move video device unregistration to the beginning of the remove function to ensure all video operations are stopped before cleaning up the worker thread and disabling PM runtime. This prevents hardware register access after the device has been powered down.

In polling mode, the hrtimer periodically triggers wave5_vpu_timer_callback() which queues work to the kthread worker. The worker executes wave5_vpu_irq_work_fn() which reads hardware registers via wave5_vdi_read_register().

The original cleanup order disabled PM runtime and powered down hardware before unregistering video devices. When autosuspend triggers and powers off the hardware, the video devices are still registered and the worker thread can still be triggered by the hrtimer, causing it to attempt reading registers from powered-off hardware. This results in a bus error (synchronous external abort) and kernel panic.

This causes random kernel panics during encoding operations:

Internal error: synchronous external abort: 0000000096000010 [#1] PREEMPT SMP Modules linked in: wave5 rpmsg_ctrl rpmsg_char ... CPU: 0 UID: 0 PID: 1520 Comm: vpu_irq_thread Tainted: G M W pc : wave5_vdi_read_register+0x10/0x38 [wave5] lr : wave5_vpu_irq_work_fn+0x28/0x60 [wave5] Call trace: wave5_vdi_read_register+0x10/0x38 [wave5] kthread_worker_fn+0xd8/0x238 k…