From: Mathias Nyman mathias.nyman@linux.intel.com

commit 44a182b9d17765514fa2b1cc911e4e65134eef93 upstream.

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: a400efe455f7 ("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 Signed-off-by: Matthias Kaehlcke mka@chromium.org --- The original fix has been integrated into some recent -stable versions, but wasn't backported to older LTS kernel like v4.9 or v4.4. The context in xhci_free_dev() changed a bit because upstream added xhci_disable_slot().

drivers/usb/host/xhci.c | 3 +++ 1 file changed, 3 insertions(+)

diff --git a/drivers/usb/host/xhci.c b/drivers/usb/host/xhci.c index c190fabd1875..e9f5f9c32b49 100644 --- a/drivers/usb/host/xhci.c +++ b/drivers/usb/host/xhci.c @@ -3656,6 +3656,9 @@ void xhci_free_dev(struct usb_hcd *hcd, struct usb_device *udev) }

spin_lock_irqsave(&xhci->lock, flags); + + virt_dev->udev = NULL; + /* Don't disable the slot if the host controller is dead. */ state = readl(&xhci->op_regs->status); if (state == 0xffffffff || (xhci->xhc_state & XHCI_STATE_DYING) ||