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usb: dwc3: gadget: Move null pinter check to proper place
commit 3c58807 upstream. When dwc3_gadget_ep_cleanup_completed_requests() called to dwc3_gadget_giveback() where the dwc3 lock is released, other thread is able to execute. In this situation, usb_ep_disable() gets the chance to clear endpoint descriptor pointer which leds to the null pointer dereference problem. So needs to move the null pointer check to a proper place. Example call stack: Thread#1: dwc3_thread_interrupt() spin_lock -> dwc3_process_event_buf() -> dwc3_process_event_entry() -> dwc3_endpoint_interrupt() -> dwc3_gadget_endpoint_trbs_complete() -> dwc3_gadget_ep_cleanup_completed_requests() ... -> dwc3_giveback() spin_unlock Thread#2 executes Thread#2: configfs_composite_disconnect() -> __composite_disconnect() -> ffs_func_disable() -> ffs_func_set_alt() -> ffs_func_eps_disable() -> usb_ep_disable() wait for dwc3 spin_lock Thread#1 released lock clear endpoint.desc Fixes: 2628844 ("usb: dwc3: gadget: Fix null pointer exception") Cc: stable <stable@kernel.org> Signed-off-by: Albert Wang <albertccwang@google.com> Link: https://lore.kernel.org/r/20220518061315.3359198-1-albertccwang@google.com Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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