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From: Ondrej Mosnacek <>
To: Greg Kroah-Hartman <>
Cc:, David Howells <>,
	Matthew Garrett <>,
	Kees Cook <>,
	Jiri Slaby <>,
	SElinux list <>,
	Linux Security Module list 
	James Morris <>,
	Linux FS Devel <>,
	Linux kernel mailing list <>
Subject: Re: [PATCH] serial: core: fix suspicious security_locked_down() call
Date: Fri, 7 May 2021 14:58:23 +0200	[thread overview]
Message-ID: <> (raw)
In-Reply-To: <>

On Fri, May 7, 2021 at 2:27 PM Greg Kroah-Hartman
<> wrote:
> On Fri, May 07, 2021 at 01:57:19PM +0200, Ondrej Mosnacek wrote:
> > The commit that added this check did so in a very strange way - first
> > security_locked_down() is called, its value stored into retval, and if
> > it's nonzero, then an additional check is made for (change_irq ||
> > change_port), and if this is true, the function returns. However, if
> > the goto exit branch is not taken, the code keeps the retval value and
> > continues executing the function. Then, depending on whether
> > uport->ops->verify_port is set, the retval value may or may not be reset
> > to zero and eventually the error value from security_locked_down() may
> > abort the function a few lines below.
> >
> > I will go out on a limb and assume that this isn't the intended behavior
> > and that an error value from security_locked_down() was supposed to
> > abort the function only in case (change_irq || change_port) is true.
> Are you _sure_ about this?
> Verification from the authors and users of this odd feature might be
> good to have, as I am loath to change how this works without them
> weighing in here.

I'm not completely sure and I'm with you on not merging this without
feedback from people involved in the original patch and/or whoever
understands the logic in said function.

Ondrej Mosnacek
Software Engineer, Linux Security - SELinux kernel
Red Hat, Inc.

  reply	other threads:[~2021-05-07 12:58 UTC|newest]

Thread overview: 4+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-05-07 11:57 [PATCH] serial: core: fix suspicious security_locked_down() call Ondrej Mosnacek
2021-05-07 12:27 ` Greg Kroah-Hartman
2021-05-07 12:58   ` Ondrej Mosnacek [this message]
2021-05-10 19:36 ` Kees Cook

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