linux-kernel - Re: Unused local variable load_addr in load_elf

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Message-ID: <20211207032346.g47nf4n6374xyaw2@gmail.com>
Date:   Tue, 7 Dec 2021 12:23:46 +0900
From:   Akira Kawata <akirakawata1@...il.com>
To:     Kees Cook <keescook@...omium.org>
Cc:     Lukas Bulwahn <lukas.bulwahn@...il.com>,
        Alexey Dobriyan <adobriyan@...il.com>,
        Alexander Viro <viro@...iv.linux.org.uk>,
        Eric Biederman <ebiederm@...ssion.com>,
        Andrew Morton <akpm@...ux-foundation.org>,
        linux-fsdevel <linux-fsdevel@...r.kernel.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        kernel-janitors <kernel-janitors@...r.kernel.org>
Subject: Re: Unused local variable load_addr in load_elf_binary()

On Mon, Dec 06, 2021 at 06:04:56PM -0800, Kees Cook wrote:
> On Mon, Dec 06, 2021 at 04:46:01PM +0100, Lukas Bulwahn wrote:
> > Dear Akira-san,
> > 
> > With commit 0c9333606e30 ("fs/binfmt_elf: Fix AT_PHDR for unusual ELF
> > files"), you have changed load_elf_binary() in ./fs/binfmt_elf.c in a
> > way such that the local variable load_addr in load_elf_binary() is not
> > used anymore.
> 
> EEk! yeah, this totally broke ELF randomization. this needs to be
> entirely reverted.
> 
> -- 
> Kees Cook

I think my patch doesn't affect on ELF randomization because it keeps
the way of load_addr calculation.


Akira Kawata