Commit 2ef47001 authored Nov 08, 2017 by Alan Stern Committed by Greg Kroah-Hartman Nov 09, 2017

USB: usbfs: compute urb->actual_length for isochronous



The USB kerneldoc says that the actual_length field "is read in
non-iso completion functions", but the usbfs driver uses it for all
URB types in processcompl().  Since not all of the host controller
drivers set actual_length for isochronous URBs, programs using usbfs
with some host controllers don't work properly.  For example, Minas
reports that a USB camera controlled by libusb doesn't work properly
with a dwc2 controller.

It doesn't seem worthwhile to change the HCDs and the documentation,
since the in-kernel USB class drivers evidently don't rely on
actual_length for isochronous transfers.  The easiest solution is for
usbfs to calculate the actual_length value for itself, by adding up
the lengths of the individual packets in an isochronous transfer.

Signed-off-by: Alan Stern <stern@rowland.harvard.edu>
CC: Minas Harutyunyan <Minas.Harutyunyan@synopsys.com>
Reported-and-tested-by: wlf <wulf@rock-chips.com>
CC: <stable@vger.kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

parent d656fa32

drivers/usb/core/devio.c

+14 −0

Original line number	Diff line number	Diff line
		@@ -1820,6 +1820,18 @@ static int proc_unlinkurb(struct usb_dev_state ps, void __user arg)
		return 0;
		}

		static void compute_isochronous_actual_length(struct urb *urb)
		{
		unsigned int i;

		if (urb->number_of_packets > 0) {
		urb->actual_length = 0;
		for (i = 0; i < urb->number_of_packets; i++)
		urb->actual_length +=
		urb->iso_frame_desc[i].actual_length;
		}
		}

		static int processcompl(struct async as, void __user __user *arg)
		{
		struct urb *urb = as->urb;
		@@ -1827,6 +1839,7 @@ static int processcompl(struct async as, void __user __user *arg)
		void __user *addr = as->userurb;
		unsigned int i;

		compute_isochronous_actual_length(urb);
		if (as->userbuffer && urb->actual_length) {
		if (copy_urb_data_to_user(as->userbuffer, urb))
		goto err_out;
		@@ -1995,6 +2008,7 @@ static int processcompl_compat(struct async as, void __user __user *arg)
		void __user *addr = as->userurb;
		unsigned int i;

		compute_isochronous_actual_length(urb);
		if (as->userbuffer && urb->actual_length) {
		if (copy_urb_data_to_user(as->userbuffer, urb))
		return -EFAULT;

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