From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753852AbdIIXHU (ORCPT ); Sat, 9 Sep 2017 19:07:20 -0400 Received: from shadbolt.e.decadent.org.uk ([88.96.1.126]:43076 "EHLO shadbolt.e.decadent.org.uk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751955AbdIIXEc (ORCPT ); Sat, 9 Sep 2017 19:04:32 -0400 Content-Type: text/plain; charset="UTF-8" Content-Disposition: inline Content-Transfer-Encoding: 8bit MIME-Version: 1.0 From: Ben Hutchings To: linux-kernel@vger.kernel.org, stable@vger.kernel.org CC: akpm@linux-foundation.org, "Dmitry Vyukov" , "Paul Moore" , "James Morris" , "Tetsuo Handa" Date: Sat, 09 Sep 2017 22:47:15 +0100 Message-ID: X-Mailer: LinuxStableQueue (scripts by bwh) Subject: [PATCH 3.16 189/233] selinux: fix double free in selinux_parse_opts_str() In-Reply-To: X-SA-Exim-Connect-IP: 2a02:8011:400e:2:6f00:88c8:c921:d332 X-SA-Exim-Mail-From: ben@decadent.org.uk X-SA-Exim-Scanned: No (on shadbolt.decadent.org.uk); SAEximRunCond expanded to false Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 3.16.48-rc1 review patch. If anyone has any objections, please let me know. ------------------ From: Paul Moore commit 023f108dcc187e34ef864bf10ed966cf25e14e2a upstream. This patch is based on a discussion generated by an earlier patch from Tetsuo Handa: * https://marc.info/?t=149035659300001&r=1&w=2 The double free problem involves the mnt_opts field of the security_mnt_opts struct, selinux_parse_opts_str() frees the memory on error, but doesn't set the field to NULL so if the caller later attempts to call security_free_mnt_opts() we trigger the problem. In order to play it safe we change selinux_parse_opts_str() to call security_free_mnt_opts() on error instead of free'ing the memory directly. This should ensure that everything is handled correctly, regardless of what the caller may do. Fixes: e0007529893c1c06 ("LSM/SELinux: Interfaces to allow FS to control mount options") Cc: Tetsuo Handa Reported-by: Dmitry Vyukov Signed-off-by: Paul Moore Signed-off-by: James Morris [bwh: Backported to 3.16: adjust context] Signed-off-by: Ben Hutchings --- security/selinux/hooks.c | 5 ++--- 1 file changed, 2 insertions(+), 3 deletions(-) --- a/security/selinux/hooks.c +++ b/security/selinux/hooks.c @@ -1000,10 +1000,8 @@ static int selinux_parse_opts_str(char * goto out_err; opts->mnt_opts_flags = kcalloc(NUM_SEL_MNT_OPTS, sizeof(int), GFP_ATOMIC); - if (!opts->mnt_opts_flags) { - kfree(opts->mnt_opts); + if (!opts->mnt_opts_flags) goto out_err; - } if (fscontext) { opts->mnt_opts[num_mnt_opts] = fscontext; @@ -1026,6 +1024,7 @@ static int selinux_parse_opts_str(char * return 0; out_err: + security_free_mnt_opts(opts); kfree(context); kfree(defcontext); kfree(fscontext);