Commit e2e2aacf authored by Mathias Nyman's avatar Mathias Nyman Committed by Greg Kroah-Hartman
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xhci: fix possible null pointer deref during xhci urb enqueue 



There is a short gap between urb being submitted and actually added to the
endpoint queue (linked). If the device is disconnected during this time
then usb core is not yet aware of the pending urb, and device may be freed
just before xhci_urq_enqueue() continues, dereferencing the freed device.

Freeing the device is protected by the xhci spinlock, so make sure we take
and keep the lock while checking that device exists, dereference it, and
add the urb to the queue.

Remove the unnecessary URB check, usb core checks it before calling
xhci_urb_enqueue()

Suggested-by: default avatarKuen-Han Tsai <khtsai@google.com>
Signed-off-by: default avatarMathias Nyman <mathias.nyman@linux.intel.com>
Link: https://lore.kernel.org/r/20231201150647.1307406-20-mathias.nyman@linux.intel.com


Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent e34900f4

drivers/usb/host/xhci.c

+23 −17
Original line number Diff line number Diff line
@@ -1521,24 +1521,7 @@ static int xhci_urb_enqueue(struct usb_hcd *hcd, struct urb *urb, gfp_t mem_flag 
	struct urb_priv	*urb_priv;

	int num_tds;



	if (!urb)

		return -EINVAL;

	ret = xhci_check_args(hcd, urb->dev, urb->ep,

					true, true, __func__);

	if (ret <= 0)

		return ret ? ret : -EINVAL;



	slot_id = urb->dev->slot_id;

	ep_index = xhci_get_endpoint_index(&urb->ep->desc);

	ep_state = &xhci->devs[slot_id]->eps[ep_index].ep_state;



	if (!HCD_HW_ACCESSIBLE(hcd))

		return -ESHUTDOWN;



	if (xhci->devs[slot_id]->flags & VDEV_PORT_ERROR) {

		xhci_dbg(xhci, "Can't queue urb, port error, link inactive\n");

		return -ENODEV;

	}



	if (usb_endpoint_xfer_isoc(&urb->ep->desc))

		num_tds = urb->number_of_packets;
@@ -1562,12 +1545,35 @@ static int xhci_urb_enqueue(struct usb_hcd *hcd, struct urb *urb, gfp_t mem_flag 


	spin_lock_irqsave(&xhci->lock, flags);



	ret = xhci_check_args(hcd, urb->dev, urb->ep,

			      true, true, __func__);

	if (ret <= 0) {

		ret = ret ? ret : -EINVAL;

		goto free_priv;

	}



	slot_id = urb->dev->slot_id;



	if (!HCD_HW_ACCESSIBLE(hcd)) {

		ret = -ESHUTDOWN;

		goto free_priv;

	}



	if (xhci->devs[slot_id]->flags & VDEV_PORT_ERROR) {

		xhci_dbg(xhci, "Can't queue urb, port error, link inactive\n");

		ret = -ENODEV;

		goto free_priv;

	}



	if (xhci->xhc_state & XHCI_STATE_DYING) {

		xhci_dbg(xhci, "Ep 0x%x: URB %p submitted for non-responsive xHCI host.\n",

			 urb->ep->desc.bEndpointAddress, urb);

		ret = -ESHUTDOWN;

		goto free_priv;

	}



	ep_state = &xhci->devs[slot_id]->eps[ep_index].ep_state;



	if (*ep_state & (EP_GETTING_STREAMS | EP_GETTING_NO_STREAMS)) {

		xhci_warn(xhci, "WARN: Can't enqueue URB, ep in streams transition state %x\n",

			  *ep_state);