From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-3.6 required=3.0 tests=BAYES_00,DKIM_INVALID, DKIM_SIGNED,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE, SPF_PASS autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id B6276C4361B for ; Sun, 20 Dec 2020 21:23:29 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id 008CE2256F for ; Sun, 20 Dec 2020 21:23:28 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 008CE2256F Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=infradead.org Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id 928976B005C; Sun, 20 Dec 2020 16:23:28 -0500 (EST) Received: by kanga.kvack.org (Postfix, from userid 40) id 8D82D6B005D; Sun, 20 Dec 2020 16:23:28 -0500 (EST) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 7EEBA6B0068; Sun, 20 Dec 2020 16:23:28 -0500 (EST) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0106.hostedemail.com [216.40.44.106]) by kanga.kvack.org (Postfix) with ESMTP id 678EF6B005C for ; Sun, 20 Dec 2020 16:23:28 -0500 (EST) Received: from smtpin07.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay02.hostedemail.com (Postfix) with ESMTP id 381243640 for ; Sun, 20 Dec 2020 21:23:28 +0000 (UTC) X-FDA: 77614936896.07.plant54_2907ce027451 Received: from filter.hostedemail.com (10.5.16.251.rfc1918.com [10.5.16.251]) by smtpin07.hostedemail.com (Postfix) with ESMTP id 21D6D1803F9CF for ; Sun, 20 Dec 2020 21:23:28 +0000 (UTC) X-HE-Tag: plant54_2907ce027451 X-Filterd-Recvd-Size: 2207 Received: from casper.infradead.org (casper.infradead.org [90.155.50.34]) by imf34.hostedemail.com (Postfix) with ESMTP for ; Sun, 20 Dec 2020 21:23:25 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=casper.20170209; h=In-Reply-To:Content-Type:MIME-Version: References:Message-ID:Subject:Cc:To:From:Date:Sender:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description; bh=8CmA/+iqvN3zztpIeSvAxDsfABLhxgTfMQ78M+L2Ba4=; b=TEjAKdJAA8U/aavuONJm/+c5ee zF6zg/qV1LsfCAGQoygJKTua+2NZ60LXLY5J2UUHq36Dhu27frqRfU/QZ5haMi4kcmDIb0FQ9TfOa pb10RotAM3eH3osS79txNoTuFTsCeLk05pnnTj12UrQ6Yumm84LBNq0qkd5ciAr8z0vgopycQtakX AlcKpePovpNQaClpBZTxVvjBXhBzRniqEFo03e4LZAHj4WT6N5JpkAHUqivWwRNkym4DktZ12zUhN jXYHp6MyxHPEMrmPAgAxofG+stKTJSTbMZRacm66cwVjXwcQxkb+lVRZKebDatnOU86ogP5smsA+p Dr/5877w==; Received: from willy by casper.infradead.org with local (Exim 4.92.3 #3 (Red Hat Linux)) id 1kr6Ai-0005t5-Tu; Sun, 20 Dec 2020 21:23:21 +0000 Date: Sun, 20 Dec 2020 21:23:20 +0000 From: Matthew Wilcox To: Randy Dunlap Cc: linux-kernel@vger.kernel.org, Jens Axboe , Andrew Morton , Toralf =?iso-8859-1?Q?F=F6rster?= , linux-mm@kvack.org Subject: Re: [RFC PATCH 1/2] log2: handle LARGE input to __roundup_pow_of_two() Message-ID: <20201220212320.GA15600@casper.infradead.org> References: <20201220211037.1354-1-rdunlap@infradead.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20201220211037.1354-1-rdunlap@infradead.org> X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On Sun, Dec 20, 2020 at 01:10:37PM -0800, Randy Dunlap wrote: > UBSAN detected a 64-bit shift in log2.h:__roundup_pow_of_two(): > UBSAN: shift-out-of-bounds in ./include/linux/log2.h:57:13 > shift exponent 64 is too large for 64-bit type 'long unsigned int' > > This is during a call from mm/readahead.c:ondemand_readahead(), > get_init_ra_size(), where the 'size' parameter must have been > extremely large (or "negative"). Actually, I think it was zero, which is the real bug that should be fixed.