From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mgamail.intel.com (mgamail.intel.com [198.175.65.9]) (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 C1B493ACEED; Tue, 23 Jun 2026 20:55:00 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=198.175.65.9 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1782248102; cv=none; b=W0LjRY4gQrVaWlZEiREduKj5vrCam7wGdRFddCFW7P8nTitzv+y4boIYH2KKeCfVnLl4IQVhxH6FKAKqB0/CFOhq6kAR3nos9wDyoTSPsFa/16eVU0UZuByN9Krem0WWrxoXUhbhKTkSVYW87+Dqkpkz9PxFJBM3cXagQ9xgFcI= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1782248102; c=relaxed/simple; bh=syc5F6QF04n8Vnrj27QvpnaH5FHCJQvzFfNY8blpyHg=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=TvoG/qwhth9nzzTBl5FH/XGba7VR61DqxDx8R1/fytNjlMSm1rJtRsz3mRl5EsDQuuYea024GEUC5vCEf0EOcCPmcFxs26aI2Tv4OtGR/nB23qEq6IKZO2JQAu90439mursAH0V0ezlTewkav3KYvPLVUIj4kTYvACaGeoZj3ys= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=intel.com; spf=pass smtp.mailfrom=intel.com; dkim=pass (2048-bit key) header.d=intel.com header.i=@intel.com header.b=Yw8PBTbz; arc=none smtp.client-ip=198.175.65.9 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=intel.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=intel.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=intel.com header.i=@intel.com header.b="Yw8PBTbz" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1782248101; x=1813784101; h=date:from:to:cc:subject:message-id:references: mime-version:in-reply-to; bh=syc5F6QF04n8Vnrj27QvpnaH5FHCJQvzFfNY8blpyHg=; b=Yw8PBTbzNMBJCTPa/WvuDw+IbS/vBsPhRh1AZFlIT8ebtZTLwQ81TUYE TNiqBSSOLQUyqgRO6Am6iBSGgB/bynohpGLBaXg6Fw8XU/u9De8ASHRb3 V0NBVGDPryniURdtHEB72kDZE3dFCe27VE/K96iCd6jh9eo43CG65gV+Q PMtBzeVQ5hB+c4yWOKfLSyNBBvOHMwxedDLVERopqPEH27pbMRdUnLDc4 kZeBwlWveg5LjbJYImTFfYmElXo+aoA66KrR04sJRj+e0OoBVqkdOTdbu wyjFgLdsymMm1ShGcsehOS8Enn8iPlEybB1P8qtwVafPrh22ccqdwYsJy Q==; X-CSE-ConnectionGUID: 6v8+RkOSQp+M+klQjkKOng== X-CSE-MsgGUID: zKewsJyvQeK3t5r1QYn3Uw== X-IronPort-AV: E=McAfee;i="6800,10657,11826"; a="105796344" X-IronPort-AV: E=Sophos;i="6.24,221,1774335600"; d="scan'208";a="105796344" Received: from fmviesa004.fm.intel.com ([10.60.135.144]) by orvoesa101.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 23 Jun 2026 13:55:01 -0700 X-CSE-ConnectionGUID: 93Ojt0DUTySYIJjUQ1z7ew== X-CSE-MsgGUID: RaXgjiQSSGiWNLQfwRMujg== X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="6.24,221,1774335600"; d="scan'208";a="251554098" Received: from klitkey1-mobl1.ger.corp.intel.com (HELO localhost) ([10.245.244.7]) by fmviesa004-auth.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 23 Jun 2026 13:54:57 -0700 Date: Tue, 23 Jun 2026 23:54:55 +0300 From: Andy Shevchenko To: Bradley Morgan Cc: Andrew Morton , Kees Cook , Andy Shevchenko , Akinobu Mita , Joern Engel , Pekka Enberg , Christoph Lameter , linux-hardening@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH] lib/string: fix memchr_inv() for large ranges Message-ID: References: <20260621121133.16460-1-include@grrlz.net> Precedence: bulk X-Mailing-List: linux-hardening@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: <20260621121133.16460-1-include@grrlz.net> Organization: Intel Finland Oy - BIC 0357606-4 - c/o Alberga Business Park, 6 krs, Bertel Jungin Aukio 5, 02600 Espoo On Sun, Jun 21, 2026 at 12:11:33PM +0000, Bradley Morgan wrote: > memchr_inv() takes a size_t length but counts 8 byte words in an > unsigned int. At 32GiB that count wraps, so the scan can quietly miss > most of the range. Wow! Is it real life use case? > Use size_t for the word count. ... > @@ -837,7 +837,8 @@ void *memchr_inv(const void *start, int c, size_t bytes) > { > u8 value = c; > u64 value64; > - unsigned int words, prefix; > + size_t words; > + unsigned int prefix; Perhaps move towards reversed xmas tree while at it? unsigned int prefix; size_t words; u8 value = c; u64 value64; (same lines touched, no extra). > if (bytes <= 16) > return check_bytes8(start, value, bytes); -- With Best Regards, Andy Shevchenko