linux-kernel - Re: [PATCH] x86/cmdline: Disable instrumentation of cmdline unconditionally

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Message-ID: <20200917094055.GF31960@zn.tnic>
Date:   Thu, 17 Sep 2020 11:40:55 +0200
From:   Borislav Petkov <bp@...en8.de>
To:     Arvind Sankar <nivedita@...m.mit.edu>
Cc:     x86@...nel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] x86/cmdline: Disable instrumentation of cmdline
 unconditionally

On Sun, Sep 06, 2020 at 11:46:37AM -0400, Arvind Sankar wrote:
> On 32-bit, cmdline_find_option_bool() is used before paging is enabled,
> from check_loader_disabled_bsp() in the early microcode loader.
> Instrumentation options that insert accesses to global data will likely
> crash or corrupt memory at this point.

What is the use case here, can you trigger an actual crash?

-- 
Regards/Gruss,
    Boris.

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