Commit d710562e authored by Bryan O'Donoghue's avatar Bryan O'Donoghue Committed by Greg Kroah-Hartman
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usb: gadget: f_ecm: Use atomic_t to track in-flight request 



Currently ecm->notify_req is used to flag when a request is in-flight.
ecm->notify_req is set to NULL and when a request completes it is
subsequently reset.

This is fundamentally buggy in that the unbind logic of the ECM driver will
unconditionally free ecm->notify_req leading to a NULL pointer dereference.

Fixes: da741b8c ("usb ethernet gadget: split CDC Ethernet function")
Cc: stable <stable@vger.kernel.org>
Signed-off-by: default avatarBryan O'Donoghue <bryan.odonoghue@linaro.org>
Signed-off-by: default avatarFelipe Balbi <balbi@kernel.org>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent 5b24c28c

drivers/usb/gadget/function/f_ecm.c

+12 −4
Original line number Diff line number Diff line
@@ -52,6 +52,7 @@ struct f_ecm { 
	struct usb_ep			*notify;

	struct usb_request		*notify_req;

	u8				notify_state;

	atomic_t			notify_count;

	bool				is_open;



	/* FIXME is_open needs some irq-ish locking
@@ -380,7 +381,7 @@ static void ecm_do_notify(struct f_ecm *ecm) 
	int				status;



	/* notification already in flight? */

	if (!req)

	if (atomic_read(&ecm->notify_count))

		return;



	event = req->buf;
@@ -420,10 +421,10 @@ static void ecm_do_notify(struct f_ecm *ecm) 
	event->bmRequestType = 0xA1;

	event->wIndex = cpu_to_le16(ecm->ctrl_id);



	ecm->notify_req = NULL;

	atomic_inc(&ecm->notify_count);

	status = usb_ep_queue(ecm->notify, req, GFP_ATOMIC);

	if (status < 0) {

		ecm->notify_req = req;

		atomic_dec(&ecm->notify_count);

		DBG(cdev, "notify --> %d\n", status);

	}

}
@@ -448,17 +449,19 @@ static void ecm_notify_complete(struct usb_ep *ep, struct usb_request *req) 
	switch (req->status) {

	case 0:

		/* no fault */

		atomic_dec(&ecm->notify_count);

		break;

	case -ECONNRESET:

	case -ESHUTDOWN:

		atomic_set(&ecm->notify_count, 0);

		ecm->notify_state = ECM_NOTIFY_NONE;

		break;

	default:

		DBG(cdev, "event %02x --> %d\n",

			event->bNotificationType, req->status);

		atomic_dec(&ecm->notify_count);

		break;

	}

	ecm->notify_req = req;

	ecm_do_notify(ecm);

}
@@ -907,6 +910,11 @@ static void ecm_unbind(struct usb_configuration *c, struct usb_function *f) 


	usb_free_all_descriptors(f);



	if (atomic_read(&ecm->notify_count)) {

		usb_ep_dequeue(ecm->notify, ecm->notify_req);

		atomic_set(&ecm->notify_count, 0);

	}



	kfree(ecm->notify_req->buf);

	usb_ep_free_request(ecm->notify, ecm->notify_req);

}