Received-SPF: pass (google.com: domain of linux-kernel+bounces-33581-linux.lists.archive=gmail.com@vger.kernel.org designates 2604:1380:40f1:3f00::1 as permitted sender) client-ip=2604:1380:40f1:3f00::1;
Message-ID: <f2ee9602-0a32-4f0c-a69b-274916abe27f@exia.io>
Date: Tue, 23 Jan 2024 00:23:27 +0900
Precedence: bulk
MIME-Version: 1.0
User-Agent: Mozilla Thunderbird
Subject: Re: Recent-ish changes in binfmt_elf made my program segfault
Content-Language: en-US
To: Pedro Falcato <pedro.falcato@gmail.com>
Cc: ebiederm@xmission.com, keescook@chromium.org, linux-mm@kvack.org,
 linux-kernel@vger.kernel.org, viro@zeniv.linux.org.uk, brauner@kernel.org,
 linux-fsdevel@vger.kernel.org
References: <c7209e19-89c4-446a-b364-83100e30cc00@exia.io>
 <CAKbZUD2=W0Ng=rFVDn3UwSxtGQ5c13tRwkpqm54pPCJO0BraWA@mail.gmail.com>
From: Jan Bujak <j@exia.io>
In-Reply-To: <CAKbZUD2=W0Ng=rFVDn3UwSxtGQ5c13tRwkpqm54pPCJO0BraWA@mail.gmail.com>
Content-Type: text/plain; charset=UTF-8; format=flowed
Content-Transfer-Encoding: 7bit

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?