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 73D6D217737; Sat, 28 Jun 2025 23:40:41 +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=1751154042; cv=none; b=WSRWglQN/2irxz6KAN95VgpfPNFJkFtmcSX4A5npFOKbN8O5mggqDnLJj7fN4s04iBNI80QI6nsJ9K3U16Hr7guOaIbdHZzWttSJZMRFZXNmLVVUN3L+74lxiFBx4xM5Iz8LofumqwXJlhL1aaizocBmGTF9UBMQd3rEzVYrDUM= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1751154042; c=relaxed/simple; bh=P/RvNkMSAQeQBPjrlKokt7Nces9xjj4vKLh9m4xqU58=; h=From:To:Cc:Subject:Date:Message-Id:MIME-Version:Content-Type; b=Vk+c71RrTO6BsEdxKCTLgXSUtQ8hICVJR9j7lRhKwWMOthrRfy5rJBX/B6k0kuGOxaILhybxTPUmAaN/qaaHHvk3g0nhhr4jybtxXojQA7gfNUAl1fbR3wqfGZYAN4axQp7vcttu9LGpZnhmIZZve7M1NXIs7z7+GsiBoMndZ/M= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=lZeC64k8; 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="lZeC64k8" Received: by smtp.kernel.org (Postfix) with ESMTPSA id D8D6AC4CEEA; Sat, 28 Jun 2025 23:40:40 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1751154040; bh=P/RvNkMSAQeQBPjrlKokt7Nces9xjj4vKLh9m4xqU58=; h=From:To:Cc:Subject:Date:From; b=lZeC64k8S3hd9Xr+qm3sIquoVIDV777wnaYxYAaC+SwIa1rlGpV5WqQFa+12vnPa8 Usmb56cvKYgrxL5V8va1j2+QL1ihntOU3on6AYDbJGkUQKimlmI2YhNqSKMuhBTDx/ 0IE0KZTAOcP851cXhJ6D2ZVsYwwFlxxzSkLBIYBYqQmWUzFWgBqHho8JAlgRTv/Lxq X+VV0erEHeVfGuB2UGRsYi5jdiSIITUR3fxcaiqMWYdyWImI92jcVxBuTZD47cxKA0 hZyvrwkRH03x5xvCmGCASr8ITT1RC8hUt9RieigW438riLtOIzgb4TzFio8QIidTBL PVkDMHdYdRsJQ== From: Kees Cook To: =?UTF-8?q?Jannik=20Gl=C3=BCckert?= , Nathan Chancellor Cc: Kees Cook , linux-hardening@vger.kernel.org, Nick Desaulniers , Bill Wendling , Justin Stitt , linux-kernel@vger.kernel.org, llvm@lists.linux.dev Subject: [PATCH] kunit/fortify: Add back "volatile" for sizeof() constants Date: Sat, 28 Jun 2025 16:40:38 -0700 Message-Id: <20250628234034.work.800-kees@kernel.org> 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-Type: text/plain; charset=UTF-8 X-Developer-Signature: v=1; a=openpgp-sha256; l=1367; i=kees@kernel.org; h=from:subject:message-id; bh=P/RvNkMSAQeQBPjrlKokt7Nces9xjj4vKLh9m4xqU58=; b=owGbwMvMwCVmps19z/KJym7G02pJDBkJtaUH7CMUvCsWzt/JcjK+rZ6pZFmnbuDuhw/EVSTji 6dF8c7tKGVhEONikBVTZAmyc49z8XjbHu4+VxFmDisTyBAGLk4BmMhKa4b/sX0N/uLppVe3zrMI OF8v6nY/8Sxj/fE6zq+u94M7BJfFMDKs5z05ryv39CWN8srzckwXXGe5frrAYqPnUa/A+730720 OAA== X-Developer-Key: i=kees@kernel.org; a=openpgp; fpr=A5C3F68F229DD60F723E6E138972F4DFDC6DC026 Content-Transfer-Encoding: 8bit It seems the Clang can see through OPTIMIZER_HIDE_VAR when the constant is coming from sizeof. Adding "volatile" back to these variables solves this false positive without reintroducing the issues that originally led to switching to OPTIMIZER_HIDE_VAR in the first place[1]. Reported-by: Nathan Chancellor Closes: https://github.com/ClangBuiltLinux/linux/issues/2075 [1] Cc: "Jannik Glückert" Suggested-by: Nathan Chancellor Fixes: 6ee149f61bcc ("kunit/fortify: Replace "volatile" with OPTIMIZER_HIDE_VAR()") Signed-off-by: Kees Cook --- Cc: --- lib/tests/fortify_kunit.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/lib/tests/fortify_kunit.c b/lib/tests/fortify_kunit.c index 29ffc62a71e3..fc9c76f026d6 100644 --- a/lib/tests/fortify_kunit.c +++ b/lib/tests/fortify_kunit.c @@ -1003,8 +1003,8 @@ static void fortify_test_memcmp(struct kunit *test) { char one[] = "My mind is going ..."; char two[] = "My mind is going ... I can feel it."; - size_t one_len = sizeof(one) - 1; - size_t two_len = sizeof(two) - 1; + volatile size_t one_len = sizeof(one) - 1; + volatile size_t two_len = sizeof(two) - 1; OPTIMIZER_HIDE_VAR(one_len); OPTIMIZER_HIDE_VAR(two_len); -- 2.34.1