Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752053AbdFMIFI (ORCPT ); Tue, 13 Jun 2017 04:05:08 -0400 Received: from namei.org ([65.99.196.166]:37687 "EHLO namei.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751831AbdFMIFG (ORCPT ); Tue, 13 Jun 2017 04:05:06 -0400 Date: Tue, 13 Jun 2017 18:05:00 +1000 (AEST) From: James Morris To: Linus Torvalds cc: linux-kernel@vger.kernel.org, linux-security-module@vger.kernel.org, Paul Moore Subject: [GIT PULL] selinux: fix double free bug Message-ID: User-Agent: Alpine 2.20 (LRH 67 2015-01-07) MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2445 Lines: 71 Please pull this fix for a double free bug in SELinux. The following changes since commit 63f700aab4c11d46626de3cd051dae56cf7e9056: Merge tag 'xtensa-20170612' of git://github.com/jcmvbkbc/linux-xtensa (2017-06-13 15:09:10 +0900) are available in the git repository at: git://git.kernel.org/pub/scm/linux/kernel/git/jmorris/linux-security.git for-linus Paul Moore (1): selinux: fix double free in selinux_parse_opts_str() security/selinux/hooks.c | 5 ++--- 1 files changed, 2 insertions(+), 3 deletions(-) --- commit 023f108dcc187e34ef864bf10ed966cf25e14e2a Author: Paul Moore Date: Wed Jun 7 16:48:19 2017 -0400 selinux: fix double free in selinux_parse_opts_str() 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: stable@vger.kernel.org Cc: Tetsuo Handa Reported-by: Dmitry Vyukov Signed-off-by: Paul Moore Signed-off-by: James Morris diff --git a/security/selinux/hooks.c b/security/selinux/hooks.c index e67a526..819fd68 100644 --- a/security/selinux/hooks.c +++ b/security/selinux/hooks.c @@ -1106,10 +1106,8 @@ static int selinux_parse_opts_str(char *options, opts->mnt_opts_flags = kcalloc(NUM_SEL_MNT_OPTS, sizeof(int), GFP_KERNEL); - 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; @@ -1132,6 +1130,7 @@ static int selinux_parse_opts_str(char *options, return 0; out_err: + security_free_mnt_opts(opts); kfree(context); kfree(defcontext); kfree(fscontext);