[ 14/40] usb: config->desc.bLength may not exceed amount of data returned by the device

Greg Kroah-Hartman
2013-09-25T01:32:30Z

From: Hans de Goede <hdegoede@redhat.com>

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@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
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);