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 6DCA0C4332B for ; Fri, 20 Mar 2020 02:07:33 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 4D27720753 for ; Fri, 20 Mar 2020 02:07:33 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727297AbgCTCH2 (ORCPT ); Thu, 19 Mar 2020 22:07:28 -0400 Received: from mga01.intel.com ([192.55.52.88]:21301 "EHLO mga01.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726867AbgCTCH1 (ORCPT ); Thu, 19 Mar 2020 22:07:27 -0400 IronPort-SDR: cERMwsobxSgaDQ6DVukFbFlA9Fbaqs3xVhQ2UmtyLWIUq8Z4XF6Hx6HNyMdqy6qEHVoDMfI77F 6q/O4k1l1jQg== X-Amp-Result: SKIPPED(no attachment in message) X-Amp-File-Uploaded: False Received: from orsmga003.jf.intel.com ([10.7.209.27]) by fmsmga101.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 19 Mar 2020 19:07:27 -0700 IronPort-SDR: WiEzzFWd7aTAoICAsN40XtyFpCM6ZL+d1ZkXNh3BJ3Vi1nV2R8/rxwplPDE8ycxCDCxG4UTI9x XiL+wxuMpEeg== X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.72,282,1580803200"; d="scan'208";a="245348348" Received: from anakash-mobl2.ger.corp.intel.com (HELO localhost) ([10.251.183.74]) by orsmga003.jf.intel.com with ESMTP; 19 Mar 2020 19:07:18 -0700 Date: Fri, 20 Mar 2020 04:07:17 +0200 From: Jarkko Sakkinen To: Waiman Long Cc: David Howells , James Morris , "Serge E. Hallyn" , Mimi Zohar , "David S. Miller" , Jakub Kicinski , keyrings@vger.kernel.org, linux-kernel@vger.kernel.org, linux-security-module@vger.kernel.org, linux-integrity@vger.kernel.org, netdev@vger.kernel.org, linux-afs@lists.infradead.org, Sumit Garg , Jerry Snitselaar , Roberto Sassu , Eric Biggers , Chris von Recklinghausen Subject: Re: [PATCH v5 2/2] KEYS: Avoid false positive ENOMEM error on key read Message-ID: <20200320020717.GC183331@linux.intel.com> References: <20200318221457.1330-1-longman@redhat.com> <20200318221457.1330-3-longman@redhat.com> <20200319194650.GA24804@linux.intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: Organization: Intel Finland Oy - BIC 0357606-4 - Westendinkatu 7, 02160 Espoo Sender: owner-linux-security-module@vger.kernel.org Precedence: bulk List-ID: On Thu, Mar 19, 2020 at 08:07:55PM -0400, Waiman Long wrote: > On 3/19/20 3:46 PM, Jarkko Sakkinen wrote: > > On Wed, Mar 18, 2020 at 06:14:57PM -0400, Waiman Long wrote: > >> + * It is possible, though unlikely, that the key > >> + * changes in between the up_read->down_read period. > >> + * If the key becomes longer, we will have to > >> + * allocate a larger buffer and redo the key read > >> + * again. > >> + */ > >> + if (!tmpbuf || unlikely(ret > tmpbuflen)) { > > Shouldn't you check that tmpbuflen stays below buflen (why else > > you had made copy of buflen otherwise)? > > The check above this thunk: > > if ((ret > 0) && (ret <= buflen)) { > > will make sure that ret will not be larger than buflen. So tmpbuflen > will never be bigger than buflen. Ah right, of course, thanks. What would go wrong if the condition was instead ((ret > 0) && (ret <= tmpbuflen))? /Jarkko