[ 3.8.y.z extended stable ] Patch "usb: config->desc.bLength may not exceed amount of data returned by" has been added to staging queue

Kamal Mostafa kamal at canonical.com
Thu Sep 19 00:03:22 UTC 2013

This is a note to let you know that I have just added a patch titled

    usb: config->desc.bLength may not exceed amount of data returned by

to the linux-3.8.y-queue branch of the 3.8.y.z extended stable tree 
which can be found at:


This patch is scheduled to be released in version

If you, or anyone else, feels it should not be added to this tree, please 
reply to this email.

For more information about the 3.8.y.z tree, see



>From 90f09828c107e1fe8b25273852f105b310ae4780 Mon Sep 17 00:00:00 2001
From: Hans de Goede <hdegoede at redhat.com>
Date: Sat, 3 Aug 2013 16:37:48 +0200
Subject: usb: config->desc.bLength may not exceed amount of data returned by
 the device

commit b4f17a488ae2e09bfcf95c0e0b4219c246f1116a upstream.

While reading the config parsing code I noticed this check is missing, without
this check config->desc.wTotalLength can end up with a value larger then the
dev->rawdescriptors length for the config, and when userspace then tries to
get the rawdescriptors bad things may happen.

Signed-off-by: Hans de Goede <hdegoede at redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh at linuxfoundation.org>
Signed-off-by: Kamal Mostafa <kamal at canonical.com>
 drivers/usb/core/config.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/drivers/usb/core/config.c b/drivers/usb/core/config.c
index 7199adc..a6b2cab 100644
--- a/drivers/usb/core/config.c
+++ b/drivers/usb/core/config.c
@@ -424,7 +424,8 @@ static int usb_parse_configuration(struct usb_device *dev, int cfgidx,

 	memcpy(&config->desc, buffer, USB_DT_CONFIG_SIZE);
 	if (config->desc.bDescriptorType != USB_DT_CONFIG ||
-	    config->desc.bLength < USB_DT_CONFIG_SIZE) {
+	    config->desc.bLength < USB_DT_CONFIG_SIZE ||
+	    config->desc.bLength > size) {
 		dev_err(ddev, "invalid descriptor for config index %d: "
 		    "type = 0x%X, length = %d\n", cfgidx,
 		    config->desc.bDescriptorType, config->desc.bLength);

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