From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 2D9883AA1AB; Tue, 11 Nov 2025 12:35:01 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1762864502; cv=none; b=CWoWcbufpy4l6zRYIO4E4xwRYIJrNv/CfQiaIbmCUOeZbQgYzXhdD+ZeZUZlmxl2Zt2FLhlJcSAEb5JMai7o8/uaCDYVCGYcpooiETahgBEPE89Q6jeXvN5A0Q5ekhWcSTOlW3j52EWbPX4hXesEKioLM4MH7O05pRNfXF4IR5Y= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1762864502; c=relaxed/simple; bh=P9kSJYPFha9VBnjvxXS0Y2nT53KXisQsU5JE1jGqHp0=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=R0/qGOFIxkkHWTpZscK9pwDSxdbSM5/iFHo07gwbdGDtCR0BCtMxMegWJAvEasr7onEEWJK3KjN4N+O8ZHnoS5OyGUv0vBWIyl5PgbjSGJR5JikxH/zZk41W+fxCtegqrRVV9TKQR2kpCYJWPuq1QGACqMsvzJJtkqrqB5EFnQY= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=e955swYi; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="e955swYi" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 93172C19425; Tue, 11 Nov 2025 12:34:58 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1762864501; bh=P9kSJYPFha9VBnjvxXS0Y2nT53KXisQsU5JE1jGqHp0=; h=Date:Reply-To:Subject:To:Cc:References:From:In-Reply-To:From; b=e955swYiMNNYCa7VwRQlSOyFTTfCDSmSdI6bJgsUoU2yhrRFa1DdQu4RLICy+kYem sjrHJxwqY1uaIzocJnJFb5g0XGYJ4O9VQHKAHILWdLsFXBhZqgtuVDdw4WRqGAHOKB KOP4i2enGCjielpqLssCrG3oDgBHvsmlqYXEEe2jl7Ie1ThdZrmCbaH+5dJekpgWaP KKWTRYegj4o6a+C6hZoP5pfbfdk4JQKTFeVdwO02CEFo0a9WiiuzTozni/Oqzas7+p mHGLn4/d2ArGJ6y19mT0BBdwY3lTqIUlxKKM2iT04fITVrZGeTJEJyDtui736jtK98 ZCobIORO1MfTA== Message-ID: Date: Tue, 11 Nov 2025 13:34:56 +0100 Precedence: bulk X-Mailing-List: linux-hardening@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Reply-To: Daniel Gomez Subject: Re: [PATCH v2 0/3] module: Add compile-time check for embedded NUL characters To: Andy Shevchenko Cc: Kees Cook , Luis Chamberlain , Hans Verkuil , Malcolm Priestley , Mauro Carvalho Chehab , Hans Verkuil , =?UTF-8?Q?Uwe_Kleine-K=C3=B6nig?= , Rusty Russell , Petr Pavlu , Sami Tolvanen , linux-kernel@vger.kernel.org, linux-media@vger.kernel.org, linux-modules@vger.kernel.org, linux-hardening@vger.kernel.org References: <20251010030348.it.784-kees@kernel.org> <3dd1a00d-08f7-4801-a9f7-d6db61c0e0f3@kernel.org> Content-Language: en-US From: Daniel Gomez Organization: kernel.org In-Reply-To: Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit On 11/11/2025 12.42, Andy Shevchenko wrote: > On Wed, Nov 05, 2025 at 02:03:59PM +0100, Daniel Gomez wrote: >> On 10/10/2025 05.06, Kees Cook wrote: >>> v2: >>> - use static_assert instead of _Static_assert >>> - add Hans's Reviewed-by's >>> v1: https://lore.kernel.org/lkml/20251008033844.work.801-kees@kernel.org/ >>> >>> Hi! >>> >>> A long time ago we had an issue with embedded NUL bytes in MODULE_INFO >>> strings[1]. While this stands out pretty strongly when you look at the >>> code, and we can't do anything about a binary module that just plain lies, >>> we never actually implemented the trivial compile-time check needed to >>> detect it. >>> >>> Add this check (and fix 2 instances of needless trailing semicolons that >>> this change exposed). >>> >>> Note that these patches were produced as part of another LLM exercise. >>> This time I wanted to try "what happens if I ask an LLM to go read >>> a specific LWN article and write a patch based on a discussion?" It >>> pretty effortlessly chose and implemented a suggested solution, tested >>> the change, and fixed new build warnings in the process. >>> >>> Since this was a relatively short session, here's an overview of the >>> prompts involved as I guided it through a clean change and tried to see >>> how it would reason about static_assert vs _Static_assert. (It wanted >>> to use what was most common, not what was the current style -- we may >>> want to update the comment above the static_assert macro to suggest >>> using _Static_assert directly these days...) >>> >>> I want to fix a weakness in the module info strings. Read about it >>> here: https://lwn.net/Articles/82305/ >>> >>> Since it's only "info" that we need to check, can you reduce the checks >>> to just that instead of all the other stuff? >>> >>> I think the change to the comment is redundent, and that should be >>> in a commit log instead. Let's just keep the change to the static assert. >>> >>> Is "static_assert" the idiomatic way to use a static assert in this >>> code base? I've seen _Static_assert used sometimes. >>> >>> What's the difference between the two? >>> >>> Does Linux use C11 by default now? >>> >>> Then let's not use the wrapper any more. >>> >>> Do an "allmodconfig all -s" build to verify this works for all modules >>> in the kernel. >>> >>> >>> Thanks! >>> >>> -Kees >>> >>> [1] https://lwn.net/Articles/82305/ >>> >>> Kees Cook (3): >>> media: dvb-usb-v2: lmedm04: Fix firmware macro definitions >>> media: radio: si470x: Fix DRIVER_AUTHOR macro definition >>> module: Add compile-time check for embedded NUL characters >>> >>> include/linux/moduleparam.h | 3 +++ >>> drivers/media/radio/si470x/radio-si470x-i2c.c | 2 +- >>> drivers/media/usb/dvb-usb-v2/lmedm04.c | 12 ++++++------ >>> 3 files changed, 10 insertions(+), 7 deletions(-) >>> >> >> Reviewed-by: Daniel Gomez >> >> I have also tested a build of v6.18-rc3 + patches using allmodconfig: >> >> Tested-by: Daniel Gomez > > Folks, are you aware that this change blown up the sparse? > Now there is a "bad constant expression" to each MODULE_*() macro line. Thanks for the heads up. I can see this thread: https://lore.kernel.org/all/D1CBCBE2-3A54-410A-B15C-F1C621F9F56B@kernel.org/#t And this: https://lore.kernel.org/linux-sparse/CACePvbVG2KrGQq4cNKV=wbO5h=jp3M0RO1SdfX8kV4OukjPG8A@mail.gmail.com/T/#t > > Nice that Uwe is in the Cc list, so IIRC he is Debian maintainer for sparse > and perhaps has an influence to it to some extent. > Would it be better approach to postpone patch 3 from Kent until sparse is fixed?