linux-kernel - Re: [PATCH v2 1/2] efi+tpm: Don't access event->count when it isn't mapped.

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Message-ID: <20190925145011.GC23867@linux.intel.com>
Date:   Wed, 25 Sep 2019 17:50:11 +0300
From:   Jarkko Sakkinen <jarkko.sakkinen@...ux.intel.com>
To:     Ard Biesheuvel <ard.biesheuvel@...aro.org>
Cc:     linux-integrity <linux-integrity@...r.kernel.org>,
        Peter Jones <pjones@...hat.com>,
        linux-efi <linux-efi@...r.kernel.org>,
        stable <stable@...r.kernel.org>, Lyude Paul <lyude@...hat.com>,
        Matthew Garrett <mjg59@...gle.com>,
        Roberto Sassu <roberto.sassu@...wei.com>,
        Bartosz Szczepanek <bsz@...ihalf.com>,
        open list <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v2 1/2] efi+tpm: Don't access event->count when it isn't
 mapped.

On Wed, Sep 25, 2019 at 12:25:05PM +0200, Ard Biesheuvel wrote:
> On Wed, 25 Sep 2019 at 12:16, Jarkko Sakkinen
> <jarkko.sakkinen@...ux.intel.com> wrote:
> >
> > From: Peter Jones <pjones@...hat.com>
> >
> > Some machines generate a lot of event log entries.  When we're
> > iterating over them, the code removes the old mapping and adds a
> > new one, so once we cross the page boundary we're unmapping the page
> > with the count on it.  Hilarity ensues.
> >
> > This patch keeps the info from the header in local variables so we don't
> > need to access that page again or keep track of if it's mapped.
> >
> > Fixes: 44038bc514a2 ("tpm: Abstract crypto agile event size calculations")
> > Cc: linux-efi@...r.kernel.org
> > Cc: linux-integrity@...r.kernel.org
> > Cc: stable@...r.kernel.org
> > Signed-off-by: Peter Jones <pjones@...hat.com>
> > Tested-by: Lyude Paul <lyude@...hat.com>
> > Reviewed-by: Jarkko Sakkinen <jarkko.sakkinen@...ux.intel.com>
> > Acked-by: Matthew Garrett <mjg59@...gle.com>
> > Acked-by: Ard Biesheuvel <ard.biesheuvel@...aro.org>
> > Signed-off-by: Jarkko Sakkinen <jarkko.sakkinen@...ux.intel.com>
> 
> Thanks Jarkko.
> 
> Shall I take these through the EFI tree?

Would be great, if you could because I already sent one PR with fixes for
v5.4-rc1 yesterday.

/Jarkko