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

commit 2656a9abcf1ec8dd5fee6a75d6997a0f2fa0094e upstream.

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>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/usb/host/ehci-q.c b/drivers/usb/host/ehci-q.c
index 4b66374bdc8e33f74e20ff7bc30b7894ab24698e..3d989028c8365e6644b86428fea2f24cfba9be6e 100644 (file)
--- a/drivers/usb/host/ehci-q.c
+++ b/drivers/usb/host/ehci-q.c
@@ -264,15 +264,9 @@ ehci_urb_done(struct ehci_hcd *ehci, struct urb *urb, int status)
 __releases(ehci->lock)
 __acquires(ehci->lock)
 {
-       if (likely (urb->hcpriv != NULL)) {
-               struct ehci_qh  *qh = (struct ehci_qh *) urb->hcpriv;
-
-               /* S-mask in a QH means it's an interrupt urb */
-               if ((qh->hw->hw_info2 & cpu_to_hc32(ehci, QH_SMASK)) != 0) {
-
-                       /* ... update hc-wide periodic stats (for usbfs) */
-                       ehci_to_hcd(ehci)->self.bandwidth_int_reqs--;
-               }
+       if (usb_pipetype(urb->pipe) == PIPE_INTERRUPT) {
+               /* ... update hc-wide periodic stats */
+               ehci_to_hcd(ehci)->self.bandwidth_int_reqs--;
        }
 
        if (unlikely(urb->unlinked)) {

diff --git a/drivers/usb/host/ehci-sched.c b/drivers/usb/host/ehci-sched.c
index 7cf3da7babf0009b6732302ecef280cc01429ff6..528a54068a460fb36b777e3f93c3e97937036562 100644 (file)
--- a/drivers/usb/host/ehci-sched.c
+++ b/drivers/usb/host/ehci-sched.c
@@ -1646,7 +1646,7 @@ static void itd_link_urb(
 
        /* don't need that schedule data any more */
        iso_sched_free (stream, iso_sched);
-       urb->hcpriv = NULL;
+       urb->hcpriv = stream;
 
        ++ehci->isoc_count;
        enable_periodic(ehci);
@@ -2045,7 +2045,7 @@ static void sitd_link_urb(
 
        /* don't need that schedule data any more */
        iso_sched_free (stream, sched);
-       urb->hcpriv = NULL;
+       urb->hcpriv = stream;
 
        ++ehci->isoc_count;
        enable_periodic(ehci);