@@ -59,7 +59,16 @@ int usb_choose_configuration(struct usb_device *udev)
int num_configs;
int insufficient_power = 0;
struct usb_host_config *c, *best;
- struct usb_device_driver *udriver = to_usb_device_driver(udev->dev.driver);
+ struct usb_device_driver *udriver;
+
+ /*
+ * If a USB device (not an interface) doesn't have a driver then the
+ * kernel has no business trying to select or install a configuration
+ * for it.
+ */
+ if (!udev->dev.driver)
+ return -1;
+ udriver = to_usb_device_driver(udev->dev.driver);
if (usb_device_is_owned(udev))
return 0;
It's possible that usb_choose_configuration() can get called when a USB device has no driver. In this case the recent commit a87b8e3be926 ("usb: core: Allow subclassed USB drivers to override usb_choose_configuration()") can cause a crash since it dereferenced the driver structure without checking for NULL. Let's add a check. A USB device with no driver is an anomaly, so make usb_choose_configuration() return immediately if there is no driver. This was seen in the real world when usbguard got ahold of a r8152 device at the wrong time. It can also be simulated via this on a computer with one r8152-based USB Ethernet adapter: cd /sys/bus/usb/drivers/r8152-cfgselector to_unbind="$(ls -d *-*)" real_dir="$(readlink -f "${to_unbind}")" echo "${to_unbind}" > unbind cd "${real_dir}" echo 0 > authorized echo 1 > authorized Fixes: a87b8e3be926 ("usb: core: Allow subclassed USB drivers to override usb_choose_configuration()") Reviewed-by: Alan Stern <stern@rowland.harvard.edu> Signed-off-by: Douglas Anderson <dianders@chromium.org> --- Changes in v3: - Add comment in code, as per Alan. Changes in v2: - Return immediately if no driver, as per Alan. drivers/usb/core/generic.c | 11 ++++++++++- 1 file changed, 10 insertions(+), 1 deletion(-)