USB: fix usbfs regression

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@gmail.com>
Signed-off-by: Alan Stern <stern@rowland.harvard.edu>
CC: stable <stable@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

1 files changed, 14 insertions, 3 deletions

diff --git a/drivers/usb/core/devio.c b/drivers/usb/core/devio.c
index e909ff7b909..3466fdc5bb1 100644
--- a/drivers/usb/core/devio.c
+++ b/drivers/usb/core/devio.c
@@ -1207,6 +1207,13 @@ 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) |
@@ -1345,10 +1352,14 @@ 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))