usb: dwc3: gadget: Move null pinter check to proper place
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: 26288448120b ("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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@ -3384,14 +3384,14 @@ static bool dwc3_gadget_endpoint_trbs_complete(struct dwc3_ep *dep,
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struct dwc3 *dwc = dep->dwc;
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bool no_started_trb = true;
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if (!dep->endpoint.desc)
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return no_started_trb;
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dwc3_gadget_ep_cleanup_completed_requests(dep, event, status);
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if (dep->flags & DWC3_EP_END_TRANSFER_PENDING)
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goto out;
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if (!dep->endpoint.desc)
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return no_started_trb;
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if (usb_endpoint_xfer_isoc(dep->endpoint.desc) &&
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list_empty(&dep->started_list) &&
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(list_empty(&dep->pending_list) || status == -EXDEV))
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