linux-kernel - Re: [RFC PATCH] arm64: fix the missing ktpi= cmdline check in arm64_kernel_unmapped_at

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: <20200318113217.GA4553@sirena.org.uk>
Date:   Wed, 18 Mar 2020 11:32:17 +0000
From:   Mark Brown <broonie@...nel.org>
To:     Will Deacon <will@...nel.org>
Cc:     Mark Rutland <mark.rutland@....com>,
        Hongbo Yao <yaohongbo@...wei.com>,
        linux-kernel@...r.kernel.org, catalin.marinas@....com,
        linux-arm-kernel@...ts.infradead.org
Subject: Re: [RFC PATCH] arm64: fix the missing ktpi= cmdline check in
 arm64_kernel_unmapped_at_el0()

On Tue, Mar 17, 2020 at 09:01:54PM +0000, Will Deacon wrote:
> On Tue, Mar 17, 2020 at 04:36:38PM +0000, Mark Brown wrote:

> > I'd need to go back and retest to confirm but it looks like always had
> > the issue that we'd install some nG mappings early even with KPTI
> > disabled on the command line so your change is just restoring the
> > previous behaviour and we're no worse than we were before.

> Urgh, this code brings back really bad memories :( :( :(

Tell me about it.

> So I've hacked the following, which appears to work but damn I'd like
> somebody else to look at this. I also have a nagging feeling that you
> implemented it like this at some point, but we tried to consolidate things
> during review.

> Thoughts?

I don't think I did *exactly* this but it's familiar yeah.  It looks
sensible and I can't think of any problems but that doesn't mean there
aren't any.

Download attachment "signature.asc" of type "application/pgp-signature" (489 bytes)