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

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Date:	Wed, 3 Aug 2016 09:45:06 +0200
From:	Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:	Eryu Guan <eguan@...hat.com>
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 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?

> (The 4.6-stable tree faces the same question)

Are we just missing a patch to be applied here?

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

thanks,

greg k-h