Commit e50a322e authored Oct 09, 2014 by Josef Gajdusek Committed by Greg Kroah-Hartman Nov 03, 2014

usb: Do not re-read descriptors for wired devices in usb_authorize_device()



This patch modifies the usb_authorize_device() function such as that it does
not reload the device descriptor for wired devices. The reasons for this
are as follows:

* Some devices dislike the master requesting the descriptor from them twice,
  failing on the usb_get_device_descriptor() call with -ETIMEOUT. Observed this
  on my Pretec 16GB flash drive (4146:ba65).

* Malicious device could send two different descriptors - one before
  authorization, used by userspace to determine whether to authorize it and
  second to be actually used by the kernel when determining which drivers to
  bind.

Signed-off-by: Josef Gajdusek <atx@atx.name>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

parent dd3cf174

drivers/usb/core/hub.c

+8 −5

Original line number	Diff line number	Diff line
		@@ -2543,12 +2543,15 @@ int usb_authorize_device(struct usb_device *usb_dev)
		"can't autoresume for authorization: %d\n", result);
		goto error_autoresume;
		}

		if (usb_dev->wusb) {
		result = usb_get_device_descriptor(usb_dev, sizeof(usb_dev->descriptor));
		if (result < 0) {
		dev_err(&usb_dev->dev, "can't re-read device descriptor for "
		"authorization: %d\n", result);
		goto error_device_descriptor;
		}
		}

		usb_dev->authorized = 1;
		/* Choose and set the configuration. This registers the interfaces

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