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[128.93.83.187]) by smtp.gmail.com with ESMTPSA id 5b1f17b1804b1-49cd2922ebdsm167798735e9.3.2026.08.31.06.44.02 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 31 Aug 2026 06:44:02 -0700 (PDT) From: Ella Ma To: Julia.Lawall@inria.fr, nicolas.palix@imag.fr Cc: alansnape3058@gmail.com, linux-kernel@vger.kernel.org, cocci@inria.fr Subject: [PATCH] coccinelle: free: add a checker for `__cleanup(kfree)` usage Date: Mon, 31 Aug 2026 15:43:36 +0200 Message-Id: <20260831134336.45540-1-alansnape3058@gmail.com> X-Mailer: git-send-email 2.34.1 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" Using __cleanup(kfree) will pass the stack address of the annotated local variable to kfree functions. This will lead to invalid deallocation issues. Inspired by CVE-2026-45959 and similar bugs recently detected. Signed-off-by: Ella Ma --- scripts/coccinelle/free/cleanup-free.cocci | 94 ++++++++++++++++++++++ 1 file changed, 94 insertions(+) create mode 100644 scripts/coccinelle/free/cleanup-free.cocci diff --git a/scripts/coccinelle/free/cleanup-free.cocci b/scripts/coccinell= e/free/cleanup-free.cocci new file mode 100644 index 000000000000..cdf984ac6b44 --- /dev/null +++ b/scripts/coccinelle/free/cleanup-free.cocci @@ -0,0 +1,94 @@ +// SPDX-License-Identifier: GPL-2.0-only +/// +/// Find __cleanup(kfree) +/// Using __cleanup(kfree) will pass the stack address of the annotated +/// local variable to kfree, causing an invalid free. +/// I.e., `T v __cleanup(kfree);` --> `kfree(&v);` +/// Such usage is impossible to be correct. +/// +// Confidence: High +// Copyright: (C) 2026 Ella Ma +// Options: --no-includes --include-headers + + +// Suggesting using __free for the functions with a DEFINE_FREE definition. +// Update this list when new DEFINE_FREE definitions are added. +@free@ +attribute name __cleanup; +symbol kfree, kfree_sensitive, kvfree, kvfree_atomic; +type T; +identifier v, n; +position p; +@@ + +( + T v __cleanup@p( +( + n +& +( + kfree \| kfree_sensitive \| kvfree \| kvfree_atomic +) +) + ); +| + T v __cleanup@p( +( + n +& +( + kfree \| kfree_sensitive \| kvfree \| kvfree_atomic +) +) + ) =3D ...; +) + +@script:python depends on free@ +p << free.p; +n << free.n; +@@ + +coccilib.report.print_report( + p[0], f"ERROR: found `__cleanup({n})', do you mean `__free({n})'?") + + +// Reporting __cleanup usage for the functions without a DEFINE_FREE defin= ition. +// The following list only contains frequently used functions. Supplement = it if +// necessary. +@cleanup@ +attribute name __cleanup; +symbol kvfree_sensitive, vfree, vfree_atomic; +type T; +identifier v, n; +position p; +@@ + +( + T v __cleanup@p( +( + n +& +( + kvfree_sensitive \| vfree \| vfree_atomic +) +) + ); +| + T v __cleanup@p( +( + n +& +( + kvfree_sensitive \| vfree \| vfree_atomic +) +) + ) =3D ...; +) + +@script:python depends on cleanup@ +p << cleanup.p; +n << cleanup.n; +@@ + +coccilib.report.print_report( + p[0], f"ERROR: `__cleanup({n})' will free the annotated variable, rather= than its pointee") --=20 2.34.1