linux-kernel - Re: [PATCH] ELF: fix overflow in total mapping size calculation

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Message-Id: <20211005172129.4092cc4148bbcac36a128b55@linux-foundation.org>
Date:   Tue, 5 Oct 2021 17:21:29 -0700
From:   Andrew Morton <akpm@...ux-foundation.org>
To:     Alexey Dobriyan <adobriyan@...il.com>
Cc:     linux-kernel@...r.kernel.org, Kees Cook <keescook@...omium.org>
Subject: Re: [PATCH] ELF: fix overflow in total mapping size calculation

On Sun, 3 Oct 2021 15:11:24 +0300 Alexey Dobriyan <adobriyan@...il.com> wrote:

> Kernel assumes that ELF program headers are ordered by mapping address,
> but doesn't enforce it. It is possible to make mapping size extremely huge
> by simply shuffling first and last PT_LOAD segments.
> 
> As long as PT_LOAD segments do not overlap, it is silly to require
> sorting by v_addr anyway because mmap() doesn't care.
> 
> Don't assume PT_LOAD segments are sorted and calculate min and max
> addresses correctly.

It sounds good, but why do I have the feeling this will explode in some
unexpected fashion?  Because it's elf, and that's what it does :(