linux-kernel - Re: [PATCH] firmware: dmi: Fortify entry point length checks

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Message-ID: <CAHp75Vf+PdP2AiLOHYnKUWn5KDgvy+1poBHjHZd0hnJKTsGHtg@mail.gmail.com>
Date:   Wed, 7 Sep 2022 18:48:03 +0300
From:   Andy Shevchenko <andy.shevchenko@...il.com>
To:     Jean Delvare <jdelvare@...e.de>
Cc:     LKML <linux-kernel@...r.kernel.org>,
        Linus Torvalds <torvalds@...ux-foundation.org>
Subject: Re: [PATCH] firmware: dmi: Fortify entry point length checks

On Wed, Sep 7, 2022 at 6:21 PM Jean Delvare <jdelvare@...e.de> wrote:
> On Wed, 7 Sep 2022 17:52:10 +0300, Andy Shevchenko wrote:
> > On Wed, Sep 7, 2022 at 11:30 AM Jean Delvare <jdelvare@...e.de> wrote:

...

> > > Also fix the maximum length check, which is technically 32, not 31.
> > > It does not matter in practice as the only valid values are 31 (for
> > > SMBIOS 2.x)
> >
> > "NOTE: This value was incorrectly stated in version 2.1 of this specification as
> > 1Eh. Because of this, there might be version 2.1 implementations that
> > use either the 1Eh or the 1Fh value, but version 2.2 or later
> > implementations must use the 1Fh value."
>
> Good point, so maybe we should accept 0x1E and treat is silently as
> 0x1F (which is what we have been doing implicitly so far) for maximum
> compatibility?

At least the previous comparison covers this case, if I'm not mistaken.

-- 
With Best Regards,
Andy Shevchenko