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

Luis Henriques luis.henriques at canonical.com
Fri Sep 20 19:32:32 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

to the linux-3.5.y-queue branch of the 3.5.y.z extended stable tree 
which can be found at:


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

For more information about the 3.5.y.z tree, see



>From 49bc728e944337a4e2c733270f9de1953a74b957 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: [PATCH] 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: Luis Henriques <luis.henriques 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 f4bdd0c..78609d3 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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