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=-0.8 required=3.0 tests=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 CD0FFC3A59B for ; Fri, 30 Aug 2019 14:01:46 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id A61E523426 for ; Fri, 30 Aug 2019 14:01:46 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728120AbfH3OBp (ORCPT ); Fri, 30 Aug 2019 10:01:45 -0400 Received: from mx1.redhat.com ([209.132.183.28]:55250 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727735AbfH3OBp (ORCPT ); Fri, 30 Aug 2019 10:01:45 -0400 Received: from smtp.corp.redhat.com (int-mx01.intmail.prod.int.phx2.redhat.com [10.5.11.11]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id 35BAA18F350D; Fri, 30 Aug 2019 14:01:45 +0000 (UTC) Received: from warthog.procyon.org.uk (ovpn-120-255.rdu2.redhat.com [10.10.120.255]) by smtp.corp.redhat.com (Postfix) with ESMTP id 3BFF16012C; Fri, 30 Aug 2019 14:01:42 +0000 (UTC) Organization: Red Hat UK Ltd. Registered Address: Red Hat UK Ltd, Amberley Place, 107-111 Peascod Street, Windsor, Berkshire, SI4 1TE, United Kingdom. Registered in England and Wales under Company Registration No. 3798903 From: David Howells In-Reply-To: <20190830104912.1090-1-colin.king@canonical.com> References: <20190830104912.1090-1-colin.king@canonical.com> To: Colin King Cc: dhowells@redhat.com, linux-afs@lists.infradead.org, kernel-janitors@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH] afs: use BIT_ULL for shifting to fix integer overflow MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-ID: <3078.1567173701.1@warthog.procyon.org.uk> Date: Fri, 30 Aug 2019 15:01:41 +0100 Message-ID: <3079.1567173701@warthog.procyon.org.uk> X-Scanned-By: MIMEDefang 2.79 on 10.5.11.11 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.6.2 (mx1.redhat.com [10.5.110.63]); Fri, 30 Aug 2019 14:01:45 +0000 (UTC) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Colin King wrote: > The expression 1 << nr_slots is evaluated with 32 bit integer arithmetic > and can overflow before it is widened. If it does, it's an error on the part of the caller. See the banner comment: 1 <= nr_slots <= 9. And, in any case, if nr_slots >= 64, using BIT_ULL wouldn't help... David