tree 4b16a46e185f001f530c0ba1315371d53d165044
parent 1b36810e27a9791878e4694357ab6d4c06acc22d
author Alan Stern <stern@rowland.harvard.edu> 1352387821 -0500
committer Greg Kroah-Hartman <gregkh@linuxfoundation.org> 1352686245 -0800

USB: EHCI: bugfix: urb->hcpriv should not be NULL

This patch (as1632b) fixes a bug in ehci-hcd.  The USB core uses
urb->hcpriv to determine whether or not an URB is active; host
controller drivers are supposed to set this pointer to a non-NULL
value when an URB is queued.  However ehci-hcd sets it to NULL for
isochronous URBs, which defeats the check in usbcore.

In itself this isn't a big deal.  But people have recently found that
certain sequences of actions will cause the snd-usb-audio driver to
reuse URBs without waiting for them to complete.  In the absence of
proper checking by usbcore, the URBs get added to their endpoint list
twice.  This leads to list corruption and a system freeze.

The patch makes ehci-hcd assign a meaningful value to urb->hcpriv for
isochronous URBs.  Improving robustness always helps.

Signed-off-by: Alan Stern <stern@rowland.harvard.edu>
Reported-by: Artem S. Tashkinov <t.artem@lycos.com>
Reported-by: Christof Meerwald <cmeerw@cmeerw.org>
CC: <stable@vger.kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>