Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S965251AbdLRRgb (ORCPT ); Mon, 18 Dec 2017 12:36:31 -0500 Received: from mail.linuxfoundation.org ([140.211.169.12]:37326 "EHLO mail.linuxfoundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S934802AbdLRP7W (ORCPT ); Mon, 18 Dec 2017 10:59:22 -0500 From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Alan Stern , Andrey Konovalov Subject: [PATCH 4.9 008/177] USB: core: prevent malicious bNumInterfaces overflow Date: Mon, 18 Dec 2017 16:47:11 +0100 Message-Id: <20171218152910.269130546@linuxfoundation.org> X-Mailer: git-send-email 2.15.1 In-Reply-To: <20171218152909.823644066@linuxfoundation.org> References: <20171218152909.823644066@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 Content-Length: 1676 Lines: 47 4.9-stable review patch. If anyone has any objections, please let me know. ------------------ From: Alan Stern commit 48a4ff1c7bb5a32d2e396b03132d20d552c0eca7 upstream. A malicious USB device with crafted descriptors can cause the kernel to access unallocated memory by setting the bNumInterfaces value too high in a configuration descriptor. Although the value is adjusted during parsing, this adjustment is skipped in one of the error return paths. This patch prevents the problem by setting bNumInterfaces to 0 initially. The existing code already sets it to the proper value after parsing is complete. Signed-off-by: Alan Stern Reported-by: Andrey Konovalov Signed-off-by: Greg Kroah-Hartman --- drivers/usb/core/config.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-) --- a/drivers/usb/core/config.c +++ b/drivers/usb/core/config.c @@ -550,6 +550,9 @@ static int usb_parse_configuration(struc unsigned iad_num = 0; memcpy(&config->desc, buffer, USB_DT_CONFIG_SIZE); + nintf = nintf_orig = config->desc.bNumInterfaces; + config->desc.bNumInterfaces = 0; // Adjusted later + if (config->desc.bDescriptorType != USB_DT_CONFIG || config->desc.bLength < USB_DT_CONFIG_SIZE || config->desc.bLength > size) { @@ -563,7 +566,6 @@ static int usb_parse_configuration(struc buffer += config->desc.bLength; size -= config->desc.bLength; - nintf = nintf_orig = config->desc.bNumInterfaces; if (nintf > USB_MAXINTERFACES) { dev_warn(ddev, "config %d has too many interfaces: %d, " "using maximum allowed: %d\n",