linux-kernel - Re: [PATCH 4.4 133/146] ovl: Copy up underlying inodes ->i

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <20160803080455.GJ27776@eguan.usersys.redhat.com>
Date:	Wed, 3 Aug 2016 16:04:55 +0800
From:	Eryu Guan <eguan@...hat.com>
To:	Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Cc:	linux-kernel@...r.kernel.org, stable@...r.kernel.org,
	Vivek Goyal <vgoyal@...hat.com>,
	Miklos Szeredi <mszeredi@...hat.com>
Subject: Re: [PATCH 4.4 133/146] ovl: Copy up underlying inodes ->i_mode to
 overlay inode

On Wed, Aug 03, 2016 at 09:45:06AM +0200, Greg Kroah-Hartman wrote:
> On Wed, Aug 03, 2016 at 03:36:44PM +0800, Eryu Guan wrote:
> > On Mon, Jul 25, 2016 at 01:56:28PM -0700, Greg Kroah-Hartman wrote:
> > > 4.4-stable review patch.  If anyone has any objections, please let me know.
> > > 
> > > ------------------
> > > 
> > > From: Vivek Goyal <vgoyal@...hat.com>
> > > 
> > > commit 07a2daab49c549a37b5b744cbebb6e3f445f12bc upstream.
> > > 
> > > Right now when a new overlay inode is created, we initialize overlay
> > > inode's ->i_mode from underlying inode ->i_mode but we retain only
> > > file type bits (S_IFMT) and discard permission bits.
> > > 
> > > This patch changes it and retains permission bits too. This should allow
> > > overlay to do permission checks on overlay inode itself in task context.
> > > 
> > > [SzM] It also fixes clearing suid/sgid bits on write.
> > 
> > This patch introduced a hang when writing to suid file, fstests
> > generic/355 could reproduce the hang easily, it only failed the test
> > without this patch and didn't hang the kernel.
> > 
> > Should we skip it for now and wait for a further fix?
> 
> Does Linus's tree have the same problem?

Yes, 4.7 kernel hangs as well.

> 
> > (The 4.6-stable tree faces the same question)
> 
> Are we just missing a patch to be applied here?

AFAICT, no patch is available to fix it yet. But I've reported the bug
to Miklos (in RH bugzilla).

> 
> And this is already in the released stable kernels...

This patch is not in 4.7-rc7, it first appears in 4.7 kernel, seems like
the soak time is not long enough to let testings finish :) I finished my
4.7 kernel testing and identified the culprit this Monday.

Thanks,
Eryu