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 B188F2BDC25; Wed, 8 Oct 2025 03:59:38 +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=1759895978; cv=none; b=INDRoaLwgAjEq3AIIQ3LXrhjAwGYFEoTZXTAy1CA9nxkANN42iM5rOHGElbXLmjIec2lU4z66yi7QaNY6OHOOyrNUdR1JLgvJERBLMmkIN04geNjS+x9iXYBxhtfpxXF4xoj/aJ1qfGcIFbxZbIAHcGDSyT2niwHV3aXeRKOOMc= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1759895978; c=relaxed/simple; bh=vPUzB/kedHLN1UiYunAi6GZuZ1A/GiYXuoHbDCB5M4o=; h=From:To:Cc:Subject:Date:Message-Id:MIME-Version:Content-Type; b=aLVzpR5kS//ICMWTlkjhopdd93l05ggclsgW+FYFijugTYKoILgruEa7KsIoOAWl6qgNaFJ+5TeosKL0+XbYhab4fi7YAkmuO40YSwn6AGrOjLQd2/Zp+7FZqCdBVAkGO/Hl+KgPJsMpSn3oSbamSnq8K/1UYcxkbA9p2DXzCPs= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=qerGsF5l; 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="qerGsF5l" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 53779C4CEF4; Wed, 8 Oct 2025 03:59:38 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1759895978; bh=vPUzB/kedHLN1UiYunAi6GZuZ1A/GiYXuoHbDCB5M4o=; h=From:To:Cc:Subject:Date:From; b=qerGsF5lf8DmJqYFBYDmf4IlURtKS0YXbmifDG984jebZyIHSFw9vs/ZjCeuQXpmn tDpQNiDUa1CcKuxJ9+TIaM4wYOk2j9RRUm+0svoDvAd1WarK1IPKLNy/B+E7cmEW57 85W8Noz7TknIYF+kYHZcbs8fJKLXlrtX6T6A9uQ5t7HEWaZdsv8Ze4Pbh0dmU6qJwU +4iTKQ+lGCshOlmLAe+Y5AG1xb3wqSYbkCvPx65adrmUtEObISLVS4iuiZQ/6BAo78 bsp4m2nHdfbnwQTFB3YbXeFpGofJUvZeKrMcXZ78/DzMatDD+7ppwmjpIB6rAPQrlZ xs9cXWx8xymQQ== From: Kees Cook To: Luis Chamberlain Cc: Kees Cook , Malcolm Priestley , Mauro Carvalho Chehab , Hans Verkuil , =?UTF-8?q?Uwe=20Kleine-K=C3=B6nig?= , Rusty Russell , Petr Pavlu , Daniel Gomez , Sami Tolvanen , linux-kernel@vger.kernel.org, linux-media@vger.kernel.org, linux-modules@vger.kernel.org, linux-hardening@vger.kernel.org Subject: [PATCH 0/3] module: Add compile-time check for embedded NUL characters Date: Tue, 7 Oct 2025 20:59:32 -0700 Message-Id: <20251008033844.work.801-kees@kernel.org> X-Mailer: git-send-email 2.34.1 Precedence: bulk X-Mailing-List: linux-modules@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 X-Developer-Signature: v=1; a=openpgp-sha256; l=2403; i=kees@kernel.org; h=from:subject:message-id; bh=vPUzB/kedHLN1UiYunAi6GZuZ1A/GiYXuoHbDCB5M4o=; b=owGbwMvMwCVmps19z/KJym7G02pJDBlPHy7ljBR+Mv320ptmjW8KAibxM6zdHyC+8ax7DP/0C U8kZL9P7yhlYRDjYpAVU2QJsnOPc/F42x7uPlcRZg4rE8gQBi5OAZhI6kZGhjurND948cqdkf5W /y0hbqLU7t1NlpnZcyf/P7P0RU63cx7D/9APS9/Vt3r/SVTmLYnb7SWmnfXpnOmDCm7TiQGeZaG 53AA= X-Developer-Key: i=kees@kernel.org; a=openpgp; fpr=A5C3F68F229DD60F723E6E138972F4DFDC6DC026 Content-Transfer-Encoding: 8bit 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(-) -- 2.34.1