From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1161680AbdAJNiZ (ORCPT ); Tue, 10 Jan 2017 08:38:25 -0500 Received: from mail.linuxfoundation.org ([140.211.169.12]:59502 "EHLO mail.linuxfoundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1161578AbdAJNiR (ORCPT ); Tue, 10 Jan 2017 08:38:17 -0500 From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Alan Stern , Andrey Konovalov , Felipe Balbi Subject: [PATCH 4.4 014/101] USB: gadgetfs: fix checks of wTotalLength in config descriptors Date: Tue, 10 Jan 2017 14:36:27 +0100 Message-Id: <20170110131523.124030262@linuxfoundation.org> X-Mailer: git-send-email 2.11.0 In-Reply-To: <20170110131522.493717794@linuxfoundation.org> References: <20170110131522.493717794@linuxfoundation.org> User-Agent: quilt/0.65 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 4.4-stable review patch. If anyone has any objections, please let me know. ------------------ From: Alan Stern commit 1c069b057dcf64fada952eaa868d35f02bb0cfc2 upstream. Andrey Konovalov's fuzz testing of gadgetfs showed that we should improve the driver's checks for valid configuration descriptors passed in by the user. In particular, the driver needs to verify that the wTotalLength value in the descriptor is not too short (smaller than USB_DT_CONFIG_SIZE). And the check for whether wTotalLength is too large has to be changed, because the driver assumes there is always enough room remaining in the buffer to hold a device descriptor (at least USB_DT_DEVICE_SIZE bytes). This patch adds the additional check and fixes the existing check. It may do a little more than strictly necessary, but one extra check won't hurt. Signed-off-by: Alan Stern CC: Andrey Konovalov Signed-off-by: Felipe Balbi Signed-off-by: Greg Kroah-Hartman --- drivers/usb/gadget/legacy/inode.c | 10 +++++++--- 1 file changed, 7 insertions(+), 3 deletions(-) --- a/drivers/usb/gadget/legacy/inode.c +++ b/drivers/usb/gadget/legacy/inode.c @@ -1755,10 +1755,12 @@ static struct usb_gadget_driver probe_dr * such as configuration notifications. */ -static int is_valid_config (struct usb_config_descriptor *config) +static int is_valid_config(struct usb_config_descriptor *config, + unsigned int total) { return config->bDescriptorType == USB_DT_CONFIG && config->bLength == USB_DT_CONFIG_SIZE + && total >= USB_DT_CONFIG_SIZE && config->bConfigurationValue != 0 && (config->bmAttributes & USB_CONFIG_ATT_ONE) != 0 && (config->bmAttributes & USB_CONFIG_ATT_WAKEUP) == 0; @@ -1808,7 +1810,8 @@ dev_config (struct file *fd, const char /* full or low speed config */ dev->config = (void *) kbuf; total = le16_to_cpu(dev->config->wTotalLength); - if (!is_valid_config (dev->config) || total >= length) + if (!is_valid_config(dev->config, total) || + total > length - USB_DT_DEVICE_SIZE) goto fail; kbuf += total; length -= total; @@ -1817,7 +1820,8 @@ dev_config (struct file *fd, const char if (kbuf [1] == USB_DT_CONFIG) { dev->hs_config = (void *) kbuf; total = le16_to_cpu(dev->hs_config->wTotalLength); - if (!is_valid_config (dev->hs_config) || total >= length) + if (!is_valid_config(dev->hs_config, total) || + total > length - USB_DT_DEVICE_SIZE) goto fail; kbuf += total; length -= total;