From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail-pg1-f175.google.com (mail-pg1-f175.google.com [209.85.215.175]) (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 A4F5A18E030 for ; Tue, 30 Jul 2024 21:36:44 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.215.175 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1722375406; cv=none; b=d0vL/rq+aglx9J5NdrleIvgf48oWdXRbMY/zD9sQzPj6vTc7N2pJhXVXyPDo2a+j9rPw4rAOiI91sWtCR5bLTIL/5QQuHsZEpo9gX4/prVFvsVJKqEy+dYiMNXHQ0q38CNrcaVO6sMIWshV6R+qHApetgG3HKmXanmD/W93YShE= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1722375406; c=relaxed/simple; bh=hbXVWVMc+U/vPnGw30EF4lr9xbqKWtMfbmledmU8bOM=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=Hz3Ek9VFC67F25MHVY/AB2E9fW6cXZgTiKx/rLq1k1E9fl1J2bcu5LGNoM4X2EMc5aS436hoAoMyHNK7KMihlrRW5cWsGtT+UYLFau4JWDSYPtZn8XYe10QNxu9FWnhFlrsY5hYBgiBscY425bxzOQnLLKGCOwQFszH5EGBznaI= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=fail (p=none dis=none) header.from=kernel.org; spf=pass smtp.mailfrom=gmail.com; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b=meJr5J5t; arc=none smtp.client-ip=209.85.215.175 Authentication-Results: smtp.subspace.kernel.org; dmarc=fail (p=none dis=none) header.from=kernel.org Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=gmail.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="meJr5J5t" Received: by mail-pg1-f175.google.com with SMTP id 41be03b00d2f7-75a6c290528so3341283a12.1 for ; Tue, 30 Jul 2024 14:36:44 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20230601; t=1722375404; x=1722980204; darn=vger.kernel.org; h=in-reply-to:content-disposition:mime-version:references:message-id :subject:cc:to:from:date:sender:from:to:cc:subject:date:message-id :reply-to; bh=a9hSnC4frMwnvg6eHXjtVZhj/XkM6NEo2dL87KVmYyg=; b=meJr5J5tM5O1dvvJAdzhC+lnJ+krvt4d0KmJQ4m3/djpvwu68warEXyDTqzscwwpQ2 BT8qAoPxunWOt2PLL2gFGHWPmIAt24pBp4YBLfnr+dTbcUVkkXH93DbQSlKDUJpUa/kI hRHcGbdS5YOmF8PzR+wqJYbuS7zu9ZaLqEt59tFODRiKdVV0Elz/bYrLPg+rYTcmPBlH E1YWkNnBATkxV9DlCp/s1Po7Cnwqmr/oyFM+1oXpgU+L6ajmKcUoFav1pBBCZay83x5j AmwSD9BIpulqg0g610uHE7IWArYlXHvi3YpPLXswr0b2zON55zlEDD2aug+s+J6B0Hnb Kbzw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1722375404; x=1722980204; h=in-reply-to:content-disposition:mime-version:references:message-id :subject:cc:to:from:date:sender:x-gm-message-state:from:to:cc :subject:date:message-id:reply-to; bh=a9hSnC4frMwnvg6eHXjtVZhj/XkM6NEo2dL87KVmYyg=; b=IU3m9Fm1Oe6+avlPiJMRb3kzqeD7m4fKQ86nP5dSpml4O3Hq0mgAbpXYoPixAbQeB4 IdlD+cqt1sydmzRHcyVeeGkXYGe2wOxgC2pgYQtk0rgUqJDzS7UqNXJkZddZlRysX6vQ 6cHo6BkD+tSpEqeHK3k/EVI40Xv9P/9SSD274BVv1r+o+fHMRZ5L6IriPYcIeNFxIy10 uZLkDwCiYLImDeTrHZLtsjmu0Ie9f14DwbZejthb12pTxgIOPydqWgyRJSnJzWDg3rHe cSNF32s2vYZ3y5OalM+mUc5dwn+f0DC0dDIigwn8jZ5eG/iw5gX3M07EdC6nvWX9AwZs ArRQ== X-Gm-Message-State: AOJu0YwSw8S1V7iefa1PwOaVd//6Rs3sa/9/MFc+8PsUJJLvn8VrZaNn NXVXqf2WtWCaUZiaZ2S6rJNS5OEQIeI4MEewj1glV6xrKw5pK7Ow X-Google-Smtp-Source: AGHT+IGb8sE9/P0O1TAc2ItI3WxiepL0LrSNzyqchjkNZb+iE+QcAsw82U6hXq4Z/S0Bm4dy5dXPuw== X-Received: by 2002:a17:90b:388a:b0:2c9:679d:78a7 with SMTP id 98e67ed59e1d1-2cf7e2073b5mr10918006a91.25.1722375403674; Tue, 30 Jul 2024 14:36:43 -0700 (PDT) Received: from localhost (dhcp-141-239-149-160.hawaiiantel.net. [141.239.149.160]) by smtp.gmail.com with ESMTPSA id 98e67ed59e1d1-2cf28e43df5sm11118409a91.55.2024.07.30.14.36.42 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 30 Jul 2024 14:36:43 -0700 (PDT) Sender: Tejun Heo Date: Tue, 30 Jul 2024 11:36:41 -1000 From: Tejun Heo To: Will Deacon Cc: linux-kernel@vger.kernel.org, Lai Jiangshan Subject: Re: [PATCH] workqueue: Fix UBSAN 'subtraction overflow' error in shift_and_mask() Message-ID: References: <20240730114431.1119-1-will@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: <20240730114431.1119-1-will@kernel.org> On Tue, Jul 30, 2024 at 12:44:31PM +0100, Will Deacon wrote: ... > This is due to shift_and_mask() using a signed immediate to construct > the mask and being called with a shift of 31 (WORK_OFFQ_POOL_SHIFT) so > that it ends up decrementing from INT_MIN. > > Use an unsigned constant '1U' to generate the mask in shift_and_mask(). > > Cc: Tejun Heo > Cc: Lai Jiangshan > Fixes: 1211f3b21c2a ("workqueue: Preserve OFFQ bits in cancel[_sync] paths") > Signed-off-by: Will Deacon Applied to wq/for-6.11-fixes. Thanks. -- tejun