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Commit 67f5a4ba authored by Alan Stern's avatar Alan Stern Committed by Greg Kroah-Hartman
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USB: usb_get_string should check the descriptor type 



This patch (as1218) fixes a problem with a radio-control joystick used
in the "walkera 4#3" helicopter.  This device responds to the initial
Get-String-Descriptor request for string 0 (which is really the list
of supported languages) by sending its config descriptor!  The
usb_get_string() routine needs to check whether it got the right
type of descriptor.

Oddly enough, this sort of check is already present in
usb_get_descriptor().  The patch changes the error code from -EPROTO
to -ENODATA, because -EPROTO shows up in so many other contexts to
indicate a hardware failure rather than a firmware error.

Signed-off-by: default avatarAlan Stern <stern@rowland.harvard.edu>
Tested-by: default avatarGuillermo Jarabo <williamjap@gmail.com>
Cc: stable <stable@kernel.org>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@suse.de>

===================================================================
parent 54b9ed35

drivers/usb/core/message.c

+8 −3
Original line number Diff line number Diff line
@@ -653,7 +653,7 @@ int usb_get_descriptor(struct usb_device *dev, unsigned char type, 
		if (result <= 0 && result != -ETIMEDOUT)

			continue;

		if (result > 1 && ((u8 *)buf)[1] != type) {

			result = -EPROTO;

			result = -ENODATA;

			continue;

		}

		break;
@@ -696,7 +696,12 @@ static int usb_get_string(struct usb_device *dev, unsigned short langid, 
			USB_REQ_GET_DESCRIPTOR, USB_DIR_IN,

			(USB_DT_STRING << 8) + index, langid, buf, size,

			USB_CTRL_GET_TIMEOUT);

		if (!(result == 0 || result == -EPIPE))

		if (result == 0 || result == -EPIPE)

			continue;

		if (result > 1 && ((u8 *) buf)[1] != USB_DT_STRING) {

			result = -ENODATA;

			continue;

		}

		break;

	}

	return result;