linux-kernel - Re: [PATCH 1/1] efi/libstub: tpm: zero initialize pointer variables for mixed mode

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Message-ID: <20180316130250.GD5035@linux.intel.com>
Date:   Fri, 16 Mar 2018 15:02:50 +0200
From:   Jarkko Sakkinen <jarkko.sakkinen@...ux.intel.com>
To:     Ard Biesheuvel <ard.biesheuvel@...aro.org>
Cc:     linux-efi@...r.kernel.org, Ingo Molnar <mingo@...nel.org>,
        Thomas Gleixner <tglx@...utronix.de>, hdegoede@...hat.com,
        tweek@...gle.com, javierm@...hat.com, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 1/1] efi/libstub: tpm: zero initialize pointer variables
 for mixed mode

On Tue, Mar 13, 2018 at 02:09:21PM +0000, Ard Biesheuvel wrote:
> As reported by Jeremy, running the new TPM libstub code in mixed mode
> (i.e., 64-bit kernel on 32-bit UEFI) results in hangs when invoking
> the TCG2 protocol, or when accessing the log_tbl pool allocation.
> 
> The reason turns out to be that in both cases, the 64-bit pointer
> variables are not fully initialized by the 32-bit EFI code, and so
> we should take care to zero initialize these variables beforehand,
> or we'll end up dereferencing bogus pointers.
> 
> Reported-by: Jeremy Cline <jeremy@...ine.org>
> Signed-off-by: Ard Biesheuvel <ard.biesheuvel@...aro.org>

Reviewed-by: Jarkko Sakkinen <jarkko.sakkinen@...ux.intel.com>

/Jarkko