linux-kernel - Re: [PATCH] secretmem: use SB_I

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Message-ID: <20250708-wegrand-jungpflanze-a5940464908f@brauner>
Date: Tue, 8 Jul 2025 09:38:08 +0200
From: Christian Brauner <brauner@...nel.org>
To: Al Viro <viro@...iv.linux.org.uk>
Cc: Jens Axboe <axboe@...nel.dk>, 
	syzbot <syzbot+3de83a9efcca3f0412ee@...kaller.appspotmail.com>, jack@...e.cz, kees@...nel.org, linux-fsdevel@...r.kernel.org, 
	linux-kernel@...r.kernel.org, linux-mm@...ck.org, syzkaller-bugs@...glegroups.com, 
	Mike Rapoport <rppt@...nel.org>
Subject: Re: [PATCH] secretmem: use SB_I_NOEXEC

On Mon, Jul 07, 2025 at 06:17:35PM +0100, Al Viro wrote:
> On Mon, Jul 07, 2025 at 02:10:36PM +0200, Christian Brauner wrote:
> 
> >  static int secretmem_init_fs_context(struct fs_context *fc)
> >  {
> > -	return init_pseudo(fc, SECRETMEM_MAGIC) ? 0 : -ENOMEM;
> > +	struct pseudo_fs_context *ctx;
> > +
> > +	ctx = init_pseudo(fc, SECRETMEM_MAGIC);
> > +	if (!ctx)
> > +		return -ENOMEM;
> > +
> > +	fc->s_iflags |= SB_I_NOEXEC;
> > +	fc->s_iflags |= SB_I_NODEV;
> > +	return 0;
> >  }
> 
> What's the point of doing that *after* init_pseudo()?  IOW, why not simply
> 
> static int secretmem_init_fs_context(struct fs_context *fc)
> {
> 	fc->s_iflags |= SB_I_NOEXEC;
> 	fc->s_iflags |= SB_I_NODEV;
> 	return init_pseudo(fc, SECRETMEM_MAGIC) ? 0 : -ENOMEM;
> }
> 
> seeing that init_pseudo() won't undo those?

Seemed cleaner to do it the other way around and get rid of the ? while
at it. I don't think it matters either way.