linux-kernel - Re: [PATCH v4 1/2] module: add elf_check_module

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Message-ID: <20210615125057.GF5077@gate.crashing.org>
Date:   Tue, 15 Jun 2021 07:50:57 -0500
From:   Segher Boessenkool <segher@...nel.crashing.org>
To:     Jessica Yu <jeyu@...nel.org>
Cc:     Nicholas Piggin <npiggin@...il.com>,
        Michal Suchánek <msuchanek@...e.de>,
        linuxppc-dev@...ts.ozlabs.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v4 1/2] module: add elf_check_module_arch for module specific elf arch checks

On Tue, Jun 15, 2021 at 02:17:40PM +0200, Jessica Yu wrote:
> +int __weak elf_check_module_arch(Elf_Ehdr *hdr)
> +{
> +       return 1;
> +}

But is this a good idea?  It isn't useful to be able to attempt to load
a module not compiled for your architecture, and it increases the attack
surface tremendously.  These checks are one of the few things that can
*not* be weak symbols, imo.


Segher