[PATCH 3.2 022/149] usb: config->desc.bLength may not exceedamount of data returned by the device

[Ben Hutchings]

3.2.52-rc1 review patch.  If anyone has any objections, please let me know.

------------------

From: Hans de Goede <hdegoede@xxxxxxxxxx>

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@xxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
Signed-off-by: Ben Hutchings <ben@xxxxxxxxxxxxxxx>
---
 drivers/usb/core/config.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

--- a/drivers/usb/core/config.c
+++ b/drivers/usb/core/config.c
@@ -424,7 +424,8 @@ static int usb_parse_configuration(struc
 
 	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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