AZL-88629

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

media: mtk-jpeg: fix use-after-free in release path due to uncancelled work

The mtk_jpeg_release() function frees the context structure (ctx) without first cancelling any pending or running work in ctx->jpeg_work. This creates a race window where the workqueue callback may still be accessing the context memory after it has been freed.

Race condition:

CPU 0 (release)                    CPU 1 (workqueue)
----------------                   ------------------
close()
  mtk_jpeg_release()
                                   mtk_jpegenc_worker()
                                     ctx = work->data
                                     // accessing ctx

    kfree(ctx)  // freed!
                                     access ctx  // UAF!

The work is queued via queue_work() during JPEG encode/decode operations (via mtk_jpeg_device_run). If the device is closed while work is pending or running, the work handler will access freed memory.

Fix this by calling cancel_work_sync() BEFORE acquiring the mutex. This ordering is critical: if cancel_work_sync() is called after mutex_lock(), and the work handler also tries to acquire the same mutex, it would cause a deadlock.

Note: The open error path does NOT need cancel_work_sync() because INIT_WORK() only initializes the work structure - it does not schedule it. Work is only scheduled later during ioctl operations.