Messages in this thread | | | Date | Mon, 12 Mar 2018 15:30:21 +0100 | From | Borislav Petkov <> | Subject | Re: [PATCH v2] x86/microcode/AMD: check microcode file sanity before loading it |
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On Mon, Mar 12, 2018 at 03:10:47PM +0100, Maciej S. Szmigiero wrote: > And this current maximum was reached by CPU types added in > families < 15h during last 10+ years (the oldest supported CPU family in
You're assuming that the rate of adding patches to the microcode container won't change. You have a crystal ball which shows you the future?
Ok, enough with the bullshit.
Here's what I'll take as hardening patches:
1. Check whether the equivalence table length is not exceeding the size of the whole blob. This is the only sane limit check we can do - no arbitrary bullshit of it'll take how many years to reach some limit.
2. Add a PATCH_MAX_SIZE macro which evaluates against the max of all family patch sizes:
#define F1XH_MPB_MAX_SIZE 2048 #define F14H_MPB_MAX_SIZE 1824 #define F15H_MPB_MAX_SIZE 4096 #define F16H_MPB_MAX_SIZE 3458 #define F17H_MPB_MAX_SIZE 3200
so that future additions won't break the macro.
3. Fix install_equiv_cpu_table() to return an unsigned int
Make all the points above into separate patches, please, with proper commit messages explaining why they do what they do and test them.
Thx.
-- Regards/Gruss, Boris.
Good mailing practices for 400: avoid top-posting and trim the reply.
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