From: Borislav Petkov <bp@alien8.de>
To: "Maciej S. Szmigiero" <mail@maciej.szmigiero.name>
Cc: Ingo Molnar <mingo@redhat.com>,
Thomas Gleixner <tglx@linutronix.de>,
"H. Peter Anvin" <hpa@zytor.com>,
x86@kernel.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH v2] x86/microcode/AMD: check microcode file sanity before loading it
Date: Mon, 12 Mar 2018 14:48:53 +0100 [thread overview]
Message-ID: <20180312134853.GD9431@pd.tnic> (raw)
In-Reply-To: <df1e721c-f030-68b4-f197-2592bce97bbf@maciej.szmigiero.name>
On Mon, Mar 12, 2018 at 02:32:30PM +0100, Maciej S. Szmigiero wrote:
> "microcode_amd.bin" in linux-firmware.
That is the microcode container for all families < 0x15. And it
*happens* to have 18 entries.
So purely arbitrary:
Equivalence table (magic: AMD, type: 0, length: 288 (0x120))
============================================================
| inst_cpu | err_msk | err_cmp | eq_cpu | res |
==========================================================
| 0x00100f80 | 0x00000000 | 0x00000000 | 0x1080 | 0x0000 |
| 0x00100f81 | 0x00000000 | 0x00000000 | 0x1081 | 0x0000 |
| 0x00100f62 | 0x00000000 | 0x00000000 | 0x1062 | 0x0000 |
| 0x00100f23 | 0x00000000 | 0x00000000 | 0x1022 | 0x0000 |
| 0x00100f43 | 0x00000000 | 0x00000000 | 0x1043 | 0x0000 |
| 0x00100f91 | 0x00000000 | 0x00000000 | 0x1081 | 0x0000 |
| 0x00100f2a | 0x00000000 | 0x00000000 | 0x1020 | 0x0000 |
| 0x00100f63 | 0x00000000 | 0x00000000 | 0x1043 | 0x0000 |
| 0x00100f42 | 0x00000000 | 0x00000000 | 0x1041 | 0x0000 |
| 0x00300f10 | 0x00000000 | 0x00000000 | 0x3010 | 0x0000 |
| 0x00200f31 | 0x00000000 | 0x00000000 | 0x2031 | 0x0000 |
| 0x00100f52 | 0x00000000 | 0x00000000 | 0x1041 | 0x0000 |
| 0x00100fa0 | 0x00000000 | 0x00000000 | 0x10a0 | 0x0000 |
| 0x00100f53 | 0x00000000 | 0x00000000 | 0x1043 | 0x0000 |
| 0x00100f22 | 0x00000000 | 0x00000000 | 0x1022 | 0x0000 |
| 0x00500f10 | 0x00000000 | 0x00000000 | 0x5010 | 0x0000 |
| 0x00500f20 | 0x00000000 | 0x00000000 | 0x5020 | 0x0000 |
| 0x00000000 | 0x00000000 | 0x00000000 | 0x0000 | 0x0000 |
> There is no problem raising this value in that (future) case.
> As I wrote previously, currently the maximum used count is 18.
There is a problem because not everyone can upgrade their kernels
like you. Distros and big deployments can't just up and update their
kernels at a whim just because you imposed an arbitrary limit which you
determined would be ok.
> Not really, since even in the existing code CONTAINER_HDR_SZ (12) gets
> added to this size, then the sum is cast to a (signed) int.
> If this value is negative then the file get rejected.
That is a bug in install_equiv_cpu_table() - it should return unsigned int.
> It can be changed to the current maximum across sizes for particular
What is the "current maximum across sizes"?
--
Regards/Gruss,
Boris.
Good mailing practices for 400: avoid top-posting and trim the reply.
next prev parent reply other threads:[~2018-03-12 13:49 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-03-11 15:27 [PATCH v2] x86/microcode/AMD: check microcode file sanity before loading it Maciej S. Szmigiero
2018-03-12 9:53 ` Borislav Petkov
2018-03-12 12:56 ` Maciej S. Szmigiero
2018-03-12 13:06 ` Borislav Petkov
2018-03-12 13:32 ` Maciej S. Szmigiero
2018-03-12 13:48 ` Borislav Petkov [this message]
2018-03-12 14:10 ` Maciej S. Szmigiero
2018-03-12 14:30 ` Borislav Petkov
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