GIT: unionfs2-2.6.27.y: USB: fix usbfs regression

[Erez Zadok]

commit aaaa549b386fdd80b93b447541f42b313b103f95
Author: Alan Stern <stern at rowland.harvard.edu>
Date:   Sat Mar 6 15:04:03 2010 -0500

    USB: fix usbfs regression
    
    commit 7152b592593b9d48b33f8997b1dfd6df9143f7ec upstream.
    
    This patch (as1352) fixes a bug in the way isochronous input data is
    returned to userspace for usbfs transfers.  The entire buffer must be
    copied, not just the first actual_length bytes, because the individual
    packets will be discontiguous if any of them are short.
    
    Reported-by: Markus Rechberger <mrechberger at gmail.com>
    Signed-off-by: Alan Stern <stern at rowland.harvard.edu>
    Signed-off-by: Greg Kroah-Hartman <gregkh at suse.de>

diff --git a/drivers/usb/core/devio.c b/drivers/usb/core/devio.c
index 1902694..8657266 100644
--- a/drivers/usb/core/devio.c
+++ b/drivers/usb/core/devio.c
@@ -1123,6 +1123,13 @@ static int proc_do_submiturb(struct dev_state *ps, struct usbdevfs_urb *uurb,
 			free_async(as);
 			return -ENOMEM;
 		}
+		/* Isochronous input data may end up being discontiguous
+		 * if some of the packets are short.  Clear the buffer so
+		 * that the gaps don't leak kernel data to userspace.
+		 */
+		if (is_in && uurb->type == USBDEVFS_URB_TYPE_ISO)
+			memset(as->urb->transfer_buffer, 0,
+					uurb->buffer_length);
 	}
 	as->urb->dev = ps->dev;
 	as->urb->pipe = (uurb->type << 30) |
@@ -1224,10 +1231,14 @@ static int processcompl(struct async *as, void __user * __user *arg)
 	void __user *addr = as->userurb;
 	unsigned int i;
 
-	if (as->userbuffer && urb->actual_length)
-		if (copy_to_user(as->userbuffer, urb->transfer_buffer,
-				 urb->actual_length))
+	if (as->userbuffer && urb->actual_length) {
+		if (urb->number_of_packets > 0)		/* Isochronous */
+			i = urb->transfer_buffer_length;
+		else					/* Non-Isoc */
+			i = urb->actual_length;
+		if (copy_to_user(as->userbuffer, urb->transfer_buffer, i))
 			goto err_out;
+	}
 	if (put_user(as->status, &userurb->status))
 		goto err_out;
 	if (put_user(urb->actual_length, &userurb->actual_length))