linux-kernel - Re: [PATCH qemu] x86: don't let decompressed kernel image clobber setup

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Message-ID: <Y7BGIAL4z6o6FEI5@zn.tnic>
Date:   Sat, 31 Dec 2022 15:24:32 +0100
From:   Borislav Petkov <bp@...en8.de>
To:     "Jason A. Donenfeld" <Jason@...c4.com>,
        "H. Peter Anvin" <hpa@...or.com>
Cc:     pbonzini@...hat.com, ebiggers@...nel.org, x86@...nel.org,
        linux-kernel@...r.kernel.org, qemu-devel@...gnu.org,
        ardb@...nel.org, kraxel@...hat.com, philmd@...aro.org
Subject: Re: [PATCH qemu] x86: don't let decompressed kernel image clobber
 setup_data

On Sat, Dec 31, 2022 at 02:51:28PM +0100, Jason A. Donenfeld wrote:
> That failure is unrelated to the ident mapping issue Peter and
> I discussed. The original failure is described in the commit message:
> decompression clobbers the data, so sd->next points to garbage.

Right, and the fact that the kernel overwrites it still feels kinda wrong: the
kernel knows where setup_data is - the address is in the setup header so
*actually*, it should take care of not to clobber it.

But hpa would correct me if I'm missing an aspect about whose responsibility it
is to do what here...

Thx.

-- 
Regards/Gruss,
    Boris.

https://people.kernel.org/tglx/notes-about-netiquette