From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail-oi1-f169.google.com (mail-oi1-f169.google.com [209.85.167.169]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 8D4891426A for ; Fri, 2 Feb 2024 10:41:57 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.167.169 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1706870519; cv=none; b=KdnoitJ3Mfb7lj1HaV1PysQzjfmdhXWcbcwQBG9eutDfQLbYgGwwo2GYo+UN0Ku90mjvpw/jf0snmNjPy7jcvKncsAslCqkeZMmKYoLLQknpmzUAxejBwzEPLmzABdczlojJwyf6eI2b1aL3DndyR33q0oWbaqAKlv5+zEOk29I= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1706870519; c=relaxed/simple; bh=yMB99VXpUpL4JIlzPigdgZ92go77Y6AQyL1YrMA2+mg=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=pK410lGvKRQtofmYHp62geGkSdwfaN5n5cLmS9Kc2lLNdA9ykkkHzCaECIKoqgqDbtfBkz6CrrzNyDDqS6DUQdjiqtKWFOWtRjVj/2h5m1lPEGqu5u9nqB19bTHiYngVTfe/24oGUmr0fQ/Tae0MN3XvyLmYS3TOB2M9+vkeVog= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=chromium.org; spf=pass smtp.mailfrom=chromium.org; dkim=pass (1024-bit key) header.d=chromium.org header.i=@chromium.org header.b=LePJTtpr; arc=none smtp.client-ip=209.85.167.169 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=chromium.org Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=chromium.org Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=chromium.org header.i=@chromium.org header.b="LePJTtpr" Received: by mail-oi1-f169.google.com with SMTP id 5614622812f47-3be6b977516so1279773b6e.2 for ; Fri, 02 Feb 2024 02:41:57 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=chromium.org; s=google; t=1706870516; x=1707475316; darn=vger.kernel.org; h=in-reply-to:content-disposition:mime-version:references:message-id :subject:cc:to:from:date:from:to:cc:subject:date:message-id:reply-to; bh=GtKF1JcH99Kg94k7kIgM/vz1+rYKyXQvL//a4MKJWpg=; b=LePJTtpr4uE4GJtSc5A2Z/5x3NTx6UORojPCCP8NfW4oznML7RqeSVbCMA665GnQbU LvMkqc+NT8HqzqpILX/OMje7ZGoQP+CrOvZZDv0IROqej5rx/ZOBH56pH27xeRjwrDpi tUlTWDCbyQiUq8vhMSNSSRmDeRa04XJDeDg9I= X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1706870516; x=1707475316; h=in-reply-to:content-disposition:mime-version:references:message-id :subject:cc:to:from:date:x-gm-message-state:from:to:cc:subject:date :message-id:reply-to; bh=GtKF1JcH99Kg94k7kIgM/vz1+rYKyXQvL//a4MKJWpg=; b=A0UTWaJZMqO4LxKKTP0l5HYRxJcX2RAKBqt2svnfcIaUAblZwe3ZqMf+HNQCnwnPEL vNQKBVx1AVqtfA361j43Ku+Uv5d51KNWZyBfW/hNE2ShdIg63MjiVV4m/GZ2QDr9Iq+Q IzOr0K3LBF8aEvTjbE26U7ECaQ8sZhrxyb6js5J243ohCaCldkEC07JXhHR1jZnLHB1D MC47cn/RIh9K+qziP6aTdgtRxKY7A8EYQ5RRP+b79211KQTnZwrQc62GMZ5jfzaXLZ3U PetMC8GublqaSfVyQFXBrNZ80IMH6FALTUxQH4eu+Y90AWroInpPOmHyul5MNdl9Clgp Q1sA== X-Gm-Message-State: AOJu0YzyobENqTDMFaXNhzHyqcgdiRLgQTME+l0d/k9nqgA1PDWqyRTv FoJBUX0oWA9aquyB7rXW97iuwotpK2n34/ja+rby881fxEv14ie6yO6yy14Pjg== X-Google-Smtp-Source: AGHT+IHdnQT+y2UI8yIqSfiqP3w+VuqFutmV/hoZqs/esycYc5feNeSSMgGvTOQiAv7kPqdQTHg5+w== X-Received: by 2002:a05:6358:782:b0:178:8d3e:950c with SMTP id n2-20020a056358078200b001788d3e950cmr5729785rwj.20.1706870516692; Fri, 02 Feb 2024 02:41:56 -0800 (PST) X-Forwarded-Encrypted: i=0; AJvYcCUcGzIJg5LfmBudAHVKOlEckAQwPprdhCb3x0x5pnqeElCi7g0hV2Xt8z3l2kIywkULVbS4iSwzv+f1S+E2lULk9bqHDWsF/CPkNjo19YVn6waxdyf/alJtULRme+Z1WChLH3WoOCKGPOldKETc Received: from www.outflux.net ([198.0.35.241]) by smtp.gmail.com with ESMTPSA id it20-20020a056a00459400b006dddc5e3433sm1326606pfb.147.2024.02.02.02.41.56 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 02 Feb 2024 02:41:56 -0800 (PST) Date: Fri, 2 Feb 2024 02:41:55 -0800 From: Kees Cook To: Marco Elver Cc: kernel test robot , linux-kernel@vger.kernel.org, linux-hardening@vger.kernel.org Subject: Re: [PATCH] ubsan: Silence W=1 warnings in self-test Message-ID: <202402020239.1EEA467@keescook> References: <20240202094550.work.205-kees@kernel.org> 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=us-ascii Content-Disposition: inline In-Reply-To: On Fri, Feb 02, 2024 at 10:57:11AM +0100, Marco Elver wrote: > On Fri, 2 Feb 2024 at 10:46, Kees Cook wrote: > > > > Silence a handful of W=1 warnings in the UBSan selftest, which set > > variables without using them. For example: > > > > lib/test_ubsan.c:101:6: warning: variable 'val1' set but not used [-Wunused-but-set-variable] > > 101 | int val1 = 10; > > | ^ > > This is the shift_out_of_bounds test? It looks like the neg and wrap > variables are volatile but the written-to variables aren't. > Technically the compiler just has to emit the reads to neg and wrap, > and can entirely omit the writes to val1 and val2. > > Does making it volatile fix the warning? It does for some, but not all: ../lib/test_ubsan.c: In function 'test_ubsan_out_of_bounds': ../lib/test_ubsan.c:115:22: warning: variable 'arr' set but not used [-Wunused-but-set-variable] 115 | volatile int arr[4]; | ^~~ ../lib/test_ubsan.c:114:23: warning: variable 'above' set but not used [-Wunused-but-set-variable] 114 | volatile char above[4] = { }; /* Protect surrounding memory. */ | ^~~~~ ../lib/test_ubsan.c: In function 'test_ubsan_load_invalid_value': ../lib/test_ubsan.c:137:44: warning: variable 'eptr' set but not used [-Wunused-but-set-variable] 137 | enum ubsan_test_enum eval, eval2, *eptr; | ^~~~ ../lib/test_ubsan.c:136:26: warning: variable 'ptr' set but not used [-Wunused-but-set-variable] 136 | bool val, val2, *ptr; | ^~~ -- Kees Cook