linux-kernel - Re: Recent-ish changes in binfmt

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Date: Tue, 23 Jan 2024 00:23:27 +0900
From: Jan Bujak <j@...a.io>
To: Pedro Falcato <pedro.falcato@...il.com>
Cc: ebiederm@...ssion.com, keescook@...omium.org, linux-mm@...ck.org,
 linux-kernel@...r.kernel.org, viro@...iv.linux.org.uk, brauner@...nel.org,
 linux-fsdevel@...r.kernel.org
Subject: Re: Recent-ish changes in binfmt_elf made my program segfault

On 1/22/24 23:54, Pedro Falcato wrote:
> Hi!
>
> Where did you get that linker script?
>
> FWIW, I catched this possible issue in review, and this was already
> discussed (see my email and Eric's reply):
> https://lore.kernel.org/all/CAKbZUD3E2if8Sncy+M2YKncc_Zh08-86W6U5wR0ZMazShxbHHA@mail.gmail.com/
>
> This was my original testcase
> (https://github.com/heatd/elf-bug-questionmark), which convinced the
> loader to map .data over a cleared .bss. Your bug seems similar, but
> does the inverse: maps .bss over .data.
>

I wrote the linker script myself from scratch.

Thank you for the link to the previous discussion. So assuming this
breakage was intended my question here is - doesn't this run afoul
of the "we do not break userspace" rule?