From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1758147AbaHHUsM (ORCPT ); Fri, 8 Aug 2014 16:48:12 -0400 Received: from youngberry.canonical.com ([91.189.89.112]:40647 "EHLO youngberry.canonical.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751487AbaHHUsG (ORCPT ); Fri, 8 Aug 2014 16:48:06 -0400 From: Kamal Mostafa To: linux-kernel@vger.kernel.org, stable@vger.kernel.org, kernel-team@lists.ubuntu.com Cc: Michal Nazarewicz , Felipe Balbi , Kamal Mostafa Subject: [PATCH 3.13 021/259] usb: gadget: f_fs: fix NULL pointer dereference when there are no strings Date: Fri, 8 Aug 2014 13:37:24 -0700 Message-Id: <1407530482-4483-22-git-send-email-kamal@canonical.com> X-Mailer: git-send-email 1.9.1 In-Reply-To: <1407530482-4483-1-git-send-email-kamal@canonical.com> References: <1407530482-4483-1-git-send-email-kamal@canonical.com> MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit X-Extended-Stable: 3.13 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 3.13.11.6 -stable review patch. If anyone has any objections, please let me know. ------------------ From: Michal Nazarewicz commit f0688c8b81d2ea239c3fb0b848f623b579238d99 upstream. If the descriptors do not need any strings and user space sends empty set of strings, the ffs->stringtabs field remains NULL. Thus *ffs->stringtabs in functionfs_bind leads to a NULL pointer dereferenece. The bug was introduced by commit [fd7c9a007f: “use usb_string_ids_n()”]. While at it, remove double initialisation of lang local variable in that function. ffs->strings_count does not need to be checked in any way since in the above scenario it will remain zero and usb_string_ids_n() is a no-operation when colled with 0 argument. Signed-off-by: Michal Nazarewicz Signed-off-by: Felipe Balbi Signed-off-by: Kamal Mostafa --- drivers/usb/gadget/f_fs.c | 12 +++++++----- 1 file changed, 7 insertions(+), 5 deletions(-) diff --git a/drivers/usb/gadget/f_fs.c b/drivers/usb/gadget/f_fs.c index 241fc87..dfa83df 100644 --- a/drivers/usb/gadget/f_fs.c +++ b/drivers/usb/gadget/f_fs.c @@ -1389,11 +1389,13 @@ static int functionfs_bind(struct ffs_data *ffs, struct usb_composite_dev *cdev) ffs->ep0req->context = ffs; lang = ffs->stringtabs; - for (lang = ffs->stringtabs; *lang; ++lang) { - struct usb_string *str = (*lang)->strings; - int id = first_id; - for (; str->s; ++id, ++str) - str->id = id; + if (lang) { + for (; *lang; ++lang) { + struct usb_string *str = (*lang)->strings; + int id = first_id; + for (; str->s; ++id, ++str) + str->id = id; + } } ffs->gadget = cdev->gadget; -- 1.9.1