Commit 5b24c28c authored by Bryan O'Donoghue's avatar Bryan O'Donoghue Committed by Greg Kroah-Hartman
Browse files

usb: gadget: f_ncm: Use atomic_t to track in-flight request 



Currently ncm->notify_req is used to flag when a request is in-flight.
ncm->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 NCM driver will
unconditionally free ncm->notify_req leading to a NULL pointer dereference.

Fixes: 40d133d7 ("usb: gadget: f_ncm: convert to new function interface with backward compatibility")
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 cf2f8b63

drivers/usb/gadget/function/f_ncm.c

+13 −4
Original line number Diff line number Diff line
@@ -53,6 +53,7 @@ struct f_ncm { 
	struct usb_ep			*notify;

	struct usb_request		*notify_req;

	u8				notify_state;

	atomic_t			notify_count;

	bool				is_open;



	const struct ndp_parser_opts	*parser_opts;
@@ -547,7 +548,7 @@ static void ncm_do_notify(struct f_ncm *ncm) 
	int				status;



	/* notification already in flight? */

	if (!req)

	if (atomic_read(&ncm->notify_count))

		return;



	event = req->buf;
@@ -587,7 +588,8 @@ static void ncm_do_notify(struct f_ncm *ncm) 
	event->bmRequestType = 0xA1;

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



	ncm->notify_req = NULL;

	atomic_inc(&ncm->notify_count);



	/*

	 * In double buffering if there is a space in FIFO,

	 * completion callback can be called right after the call,
@@ -597,7 +599,7 @@ static void ncm_do_notify(struct f_ncm *ncm) 
	status = usb_ep_queue(ncm->notify, req, GFP_ATOMIC);

	spin_lock(&ncm->lock);

	if (status < 0) {

		ncm->notify_req = req;

		atomic_dec(&ncm->notify_count);

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

	}

}
@@ -632,17 +634,19 @@ static void ncm_notify_complete(struct usb_ep *ep, struct usb_request *req) 
	case 0:

		VDBG(cdev, "Notification %02x sent\n",

		     event->bNotificationType);

		atomic_dec(&ncm->notify_count);

		break;

	case -ECONNRESET:

	case -ESHUTDOWN:

		atomic_set(&ncm->notify_count, 0);

		ncm->notify_state = NCM_NOTIFY_NONE;

		break;

	default:

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

			event->bNotificationType, req->status);

		atomic_dec(&ncm->notify_count);

		break;

	}

	ncm->notify_req = req;

	ncm_do_notify(ncm);

	spin_unlock(&ncm->lock);

}
@@ -1649,6 +1653,11 @@ static void ncm_unbind(struct usb_configuration *c, struct usb_function *f) 
	ncm_string_defs[0].id = 0;

	usb_free_all_descriptors(f);



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

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

		atomic_set(&ncm->notify_count, 0);

	}



	kfree(ncm->notify_req->buf);

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

}