Commit 44a182b9 authored May 03, 2018 by Mathias Nyman Committed by Greg Kroah-Hartman May 03, 2018

xhci: Fix use-after-free in xhci_free_virt_device



KASAN found a use-after-free in xhci_free_virt_device+0x33b/0x38e
where xhci_free_virt_device() sets slot id to 0 if udev exists:
if (dev->udev && dev->udev->slot_id)
	dev->udev->slot_id = 0;

dev->udev will be true even if udev is freed because dev->udev is
not set to NULL.

set dev->udev pointer to NULL in xhci_free_dev()

The original patch went to stable so this fix needs to be applied
there as well.

Fixes: a400efe4 ("xhci: zero usb device slot_id member when disabling and freeing a xhci slot")
Cc: <stable@vger.kernel.org>
Reported-by: Guenter Roeck <linux@roeck-us.net>
Reviewed-by: Guenter Roeck <linux@roeck-us.net>
Tested-by: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Mathias Nyman <mathias.nyman@linux.intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

parent 9aea9b6c

drivers/usb/host/xhci.c

+1 −0

Original line number	Diff line number	Diff line
		@@ -3621,6 +3621,7 @@ static void xhci_free_dev(struct usb_hcd hcd, struct usb_device udev)
		del_timer_sync(&virt_dev->eps[i].stop_cmd_timer);
		}
		xhci_debugfs_remove_slot(xhci, udev->slot_id);
		virt_dev->udev = NULL;
		ret = xhci_disable_slot(xhci, udev->slot_id);
		if (ret)
		xhci_free_virt_device(xhci, udev->slot_id);

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