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From: Greg KH on 30 Mar 2010 19:20
2.6.31-stable review patch. If anyone has any objections, please let us know.

------------------

From: Alan Stern <stern(a)rowland.harvard.edu>

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(a)gmail.com>
Signed-off-by: Alan Stern <stern(a)rowland.harvard.edu>
Signed-off-by: Greg Kroah-Hartman <gregkh(a)suse.de>

---
drivers/usb/core/devio.c | 17 ++++++++++++++---
1 file changed, 14 insertions(+), 3 deletions(-)

--- a/drivers/usb/core/devio.c
+++ b/drivers/usb/core/devio.c
@@ -1139,6 +1139,13 @@ static int proc_do_submiturb(struct dev_
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) |
@@ -1240,10 +1247,14 @@ static int processcompl(struct async *as
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))


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