From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail.linuxfoundation.org ([140.211.169.12]:36434 "EHLO mail.linuxfoundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752212AbeA3WqS (ORCPT ); Tue, 30 Jan 2018 17:46:18 -0500 Date: Tue, 30 Jan 2018 23:46:14 +0100 From: Greg KH To: Mark Salyzyn Cc: Stephen Smalley , linux-kernel@vger.kernel.org, Paul Moore , Eric Paris , James Morris , "Serge E. Hallyn" , selinux@tycho.nsa.gov, linux-security-module@vger.kernel.org, stable@vger.kernel.org Subject: Re: [PATCH] general protection fault in sock_has_perm Message-ID: <20180130224614.GA13647@kroah.com> References: <20180118215853.228182-1-salyzyn@android.com> <1516382386.2560.11.camel@tycho.nsa.gov> <1516383672.2560.23.camel@tycho.nsa.gov> <99c11fa6-ad9a-830c-467e-6a56e78aecf8@android.com> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <99c11fa6-ad9a-830c-467e-6a56e78aecf8@android.com> Sender: stable-owner@vger.kernel.org List-ID: On Tue, Jan 30, 2018 at 11:00:04AM -0800, Mark Salyzyn wrote: > On 01/19/2018 09:41 AM, Stephen Smalley wrote: > > If we can't safely dereference the sock in these hooks, then that seems > > to point back to the approach used in my original code, where in > > ancient history I had sock_has_perm() take the socket and use its inode > > i_security field instead of the sock. commit > > 253bfae6e0ad97554799affa0266052968a45808 switched them to use the sock > > instead. > > Because of the nature of this problem (hard to duplicate, no clear path), I > am understandably not comfortable reverting and submitting for testing in > order to prove this point. It is disruptive because it changes several > subroutine call signatures. > > AFAIK this looks like a user request racing in without reference counting or > RCU grace period in the callers (could be viewed as not an issue with > security code). Effectively fixed in 4.9-stable, but broken in 4.4-stable. > > hygiene, KISS and small, is all I do feel comfortable to submit to > 4.4-stable without pulling in all the infrastructure improvements. > > -- Mark > > --- > �security/selinux/hooks.c | 2 ++ > �1 file changed, 2 insertions(+) > > diff --git a/security/selinux/hooks.c b/security/selinux/hooks.c > index 34427384605d..be68992a28cb 100644 > --- a/security/selinux/hooks.c > +++ b/security/selinux/hooks.c > @@ -4066,6 +4066,8 @@ static int sock_has_perm(struct task_struct *task, > struct sock *sk, u32 perms) > ���� struct lsm_network_audit net = {0,}; > ���� u32 tsid = task_sid(task); > > +��� if (!sksec) > +��� ��� return -EFAULT; > ���� if (sksec->sid == SECINITSID_KERNEL) > ���� ��� return 0; > This looks sane to me as a simple 4.4-only fix. If the SELinux maintainer acks it, I can easily queue this up. thanks, greg k-h