linux-hardening - Re: [RFC PATCH 0/2] Add cleanup_plugin for detecting problematic cleanup patterns

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Message-ID: <19a53424397.26d1e5f01471331.8175059524177790573@linux.beauty>
Date: Wed, 05 Nov 2025 17:04:02 +0800
From: Li Chen <me@...ux.beauty>
To: "Kees Cook" <kees@...nel.org>, "Nathan Chancellor" <nathan@...nel.org>,
	"Nicolas Schier" <nicolas.schier@...ux.dev>,
	"linux-kernel" <linux-kernel@...r.kernel.org>,
	"linux-hardening" <linux-hardening@...r.kernel.org>,
	"linux-kbuild" <linux-kbuild@...r.kernel.org>,
	"Dan Williams" <dan.j.williams@...el.com>,
	"Peter Zijlstra" <peterz@...radead.org>,
	"Bjorn Helgaas" <bhelgaas@...gle.com>
Subject: Re: [RFC PATCH 0/2] Add cleanup_plugin for detecting problematic
 cleanup patterns

+Peter, Dan, and Bjorn

(My apologies for the oversight)

 ---- On Wed, 05 Nov 2025 16:46:55 +0800  Li Chen <me@...ux.beauty> wrote --- 
 > From: Li Chen <chenl311@...natelecom.cn>
 > 
 > Hello,
 > 
 > This patch series introduces a new GCC plugin called cleanup_plugin that
 > warns developers about problematic patterns when using variables with
 > __attribute__((cleanup(...))). The plugin addresses concerns documented
 > in include/linux/cleanup.h regarding resource leaks and interdependency
 > issues.
 > 
 > The cleanup attribute helpers (__free, DEFINE_FREE, etc.) are designed
 > to automatically clean up resources when variables go out of scope,
 > following LIFO (last in first out) ordering. However, certain patterns
 > can lead to subtle bugs:
 > 
 > 1. Uninitialized cleanup variables: Variables declared with cleanup
 >    attributes but not initialized can cause issues when cleanup functions
 >    are called on undefined values.
 > 
 > 2. NULL-initialized cleanup variables: The "__free(...) = NULL" pattern
 >    at function top can cause interdependency problems, especially when
 >    combined with guards or multiple cleanup variables, as the cleanup
 >    may run in unexpected contexts.
 > 
 > The plugin detects both of these problematic patterns and provides clear
 > warnings to developers, helping prevent  incorrect cleanup ordering.
 > Importantly, the plugin's warnings are not converted
 > to errors by -Werror, allowing builds to continue while still alerting
 > developers to potential issues.
 > 
 > The plugin is enabled by default as it provides valuable compile-time
 > feedback without impacting build performance.
 > 
 > Li Chen (2):
 >   gcc-plugins: add cleanup_plugin for uninitialized cleanup detection
 >   gcc-plugins: cleanup_plugin: detect NULL init
 > 
 >  scripts/Makefile.gcc-plugins         |   1 +
 >  scripts/gcc-plugins/Kconfig          |   6 +
 >  scripts/gcc-plugins/cleanup_plugin.c | 204 +++++++++++++++++++++++++++
 >  3 files changed, 211 insertions(+)
 >  create mode 100644 scripts/gcc-plugins/cleanup_plugin.c
 > 
 > -- 
 > 2.51.0
 > 
 > 
Regards,

Li