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From: Greg KH <gregkh@linuxfoundation.org>
To: Andi Kleen <ak@linux.intel.com>
Cc: Andi Kleen <andi@firstfloor.org>,
	x86@kernel.org, keescook@chromium.org,
	linux-kernel@vger.kernel.org, sashal@kernel.org,
	stable@vger.kernel.org
Subject: Re: [PATCH v1] x86: Pin cr4 FSGSBASE
Date: Tue, 26 May 2020 18:32:35 +0200	[thread overview]
Message-ID: <20200526163235.GA42137@kroah.com> (raw)
In-Reply-To: <20200526154835.GW499505@tassilo.jf.intel.com>

On Tue, May 26, 2020 at 08:48:35AM -0700, Andi Kleen wrote:
> On Tue, May 26, 2020 at 08:56:18AM +0200, Greg KH wrote:
> > On Mon, May 25, 2020 at 10:28:48PM -0700, Andi Kleen wrote:
> > > From: Andi Kleen <ak@linux.intel.com>
> > > 
> > > Since there seem to be kernel modules floating around that set
> > > FSGSBASE incorrectly, prevent this in the CR4 pinning. Currently
> > > CR4 pinning just checks that bits are set, this also checks
> > > that the FSGSBASE bit is not set, and if it is clears it again.
> > 
> > So we are trying to "protect" ourselves from broken out-of-tree kernel
> > modules now?  
> 
> Well it's a specific case where we know they're opening a root hole
> unintentionally. This is just an pragmatic attempt to protect the users in the 
> short term.

Can't you just go and fix those out-of-tree kernel modules instead?
What's keeping you all from just doing that instead of trying to force
the kernel to play traffic cop?

thanks,

greg k-h

  parent reply	other threads:[~2020-05-26 16:32 UTC|newest]

Thread overview: 17+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-05-26  5:28 [PATCH v1] x86: Pin cr4 FSGSBASE Andi Kleen
2020-05-26  6:56 ` Greg KH
2020-05-26  7:57   ` Peter Zijlstra
2020-05-26  8:17     ` Greg KH
2020-05-26  9:17       ` Peter Zijlstra
2020-05-26 10:16         ` Greg KH
2020-05-26 15:48   ` Andi Kleen
2020-05-26 16:20     ` Kees Cook
2020-05-26 16:32     ` Greg KH [this message]
2020-05-26 17:24       ` Wojtek Porczyk
2020-05-27  7:07         ` Greg KH
2020-05-27 10:58           ` Wojtek Porczyk
2020-05-26 16:15   ` Kees Cook
2020-05-26 21:16     ` Greg KH
2020-05-26 16:38 ` Kees Cook
2020-05-26 23:14   ` Andi Kleen
2020-05-27 10:31     ` Peter Zijlstra

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