usb: gadget: udc: bdc: free IRQ and drain func_wake_notify before teardown

Summary

In the Linux kernel, the following vulnerability has been resolved: usb: gadget: udc: bdc: free IRQ and drain func_wake_notify before teardown The Broadcom BDC UDC driver registers its IRQ handler with devm_request_irq() in bdc_udc_init(), so the IRQ is released by devm only after bdc_remove() returns. devm releases resources in reverse LIFO order, but bdc_remove() runs bdc_udc_exit() and bdc_hw_exit() -> bdc_mem_free() manually before returning: bdc_udc_exit() tears down individual endpoint objects via bdc_free_ep(), while bdc_hw_exit() -> bdc_mem_free() frees and NULLs the DMA-coherent status-report ring (bdc->srr.sr_bds) and kfree()s bdc->bdc_ep_array. Both happen while the IRQ handler (bdc_udc_interrupt, requested with IRQF_SHARED) remains deliverable in the window up to the post-remove devm free_irq(). On receipt of a shared interrupt in that window, bdc_udc_interrupt() dereferences bdc->srr.sr_bds[bdc->srr.dqp_index] (NULL or freed DMA) and dispatches sr_handler callbacks that index into bdc_ep_array, causing a NULL-deref or use-after-free. The same window affects the delayed_work bdc->func_wake_notify, which is armed from the IRQ handler via bdc_sr_uspc() -> handle_link_state_change() -> schedule_delayed_work() and may self-rearm from its own callback bdc_func_wake_timer(). No cancel exists anywhere in the driver, so a queued work item that fires after bdc_remove() returns and the bdc structure is devm-freed dereferences freed memory. Replace devm_request_irq() with request_irq() and add an explicit free_irq(bdc->irq, bdc) in bdc_remove(). Clear BDC_GIE before free_irq() to stop the device from asserting interrupts, then free_irq() drains any in-flight handler, then cancel_delayed_work_sync() drains the func_wake_notify delayed work. This ordering ensures the IRQ handler and delayed work cannot interfere with the subsequent endpoint and DMA teardown in bdc_udc_exit() and bdc_hw_exit(). Wire the matching free_irq() into the bdc_udc_init() error path so the IRQ is released on probe failure, and route the bdc_init_ep() failure through err0 instead of returning directly. This issue was found by an in-house static analysis tool.