linux-kernel - Re: [PATCH v6 8/8] x86/microcode/AMD: Don't scan past the CPU equivalence table data

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Message-ID: <20180605085506.GB27701@nazgul.tnic>
Date:   Tue, 5 Jun 2018 10:55:06 +0200
From:   Borislav Petkov <bp@...en8.de>
To:     "Maciej S. Szmigiero" <mail@...iej.szmigiero.name>
Cc:     Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...hat.com>,
        "H. Peter Anvin" <hpa@...or.com>, x86@...nel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH v6 8/8] x86/microcode/AMD: Don't scan past the CPU
 equivalence table data

On Sun, May 20, 2018 at 12:07:22AM +0200, Maciej S. Szmigiero wrote:
> Currently, the code scanning a CPU equivalence table read from a microcode
> container file assumes that it actually contains a terminating zero entry,
> but if does not then the code will continue the scan past its valid data.
> 
> For the late loader this can be improved by always appending a terminating
> zero entry to such table when loading it.
> This way we don't need an extra global variable for holding the table size
> and we don't have to reject such incomplete tables (for backward
> compatibility with the existing code which didn't do so).
> 
> For the early loader, since we can't allocate memory and have to work
> in-place, let's pass an explicit size of this table to its scanning
> functions so they will know when to stop.

I don't like the difference between early and late here. Just pass
explicit size to the late loader too.

-- 
Regards/Gruss,
    Boris.

ECO tip #101: Trim your mails when you reply.
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