linux-kernel - Re: [PATCH] firmware: dmi_scan: Prevent dmi

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Message-ID: <1427375705.4261.2.camel@chaos.site>
Date:	Thu, 26 Mar 2015 14:15:05 +0100
From:	Jean Delvare <jdelvare@...e.de>
To:	Matt Fleming <matt@...eblueprint.co.uk>
Cc:	LKML <linux-kernel@...r.kernel.org>,
	Matt Fleming <matt.fleming@...el.com>,
	Ard Biesheuvel <ard.biesheuvel@...aro.org>,
	Ivan Khoronzhuk <ivan.khoronzhuk@...aro.org>
Subject: Re: [PATCH] firmware: dmi_scan: Prevent dmi_num integer overflow

Hi Matt,

Le Thursday 26 March 2015 à 13:06 +0000, Matt Fleming a écrit :
> On Fri, 20 Mar, at 09:59:47AM, Jean Delvare wrote:
> > dmi_num is a u16, dmi_len is a u32, so this construct:
> > 
> > 	dmi_num = dmi_len / 4;
> > 
> > would result in an integer overflow for a DMI table larger than
> > 256 kB. I've never see such a large table so far, but SMBIOS 3.0
> > makes it possible so maybe we'll see such tables in the future.
> > 
> > So instead of faking a structure count when the entry point does
> > not provide it, adjust the loop condition in dmi_table() to properly
> > deal with the case where dmi_num is not set.
> > 
> > Signed-off-by: Jean Delvare <jdelvare@...e.de>
> > Cc: Matt Fleming <matt.fleming@...el.com>
> > Cc: Ard Biesheuvel <ard.biesheuvel@...aro.org>
> > Cc: Ivan Khoronzhuk <ivan.khoronzhuk@...aro.org>
> > ---
> >  drivers/firmware/dmi_scan.c |   22 +++++++---------------
> >  1 file changed, 7 insertions(+), 15 deletions(-)
> 
> Jean, are you taking this through your tree?

I don't actually have a tree, so feel free to pick it.

Thanks,
-- 
Jean Delvare
SUSE L3 Support

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