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=-3.8 required=3.0 tests=BAYES_00, 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 59053C433ED for ; Thu, 6 May 2021 13:42:38 +0000 (UTC) Received: from lists.gnu.org (lists.gnu.org [209.51.188.17]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id CEFC8610FA for ; Thu, 6 May 2021 13:42:37 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org CEFC8610FA Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=bugs.launchpad.net Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Received: from localhost ([::1]:34162 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1leeGx-0004Pw-UH for qemu-devel@archiver.kernel.org; Thu, 06 May 2021 09:42:36 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]:57450) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1leeFb-0002fL-Lo for qemu-devel@nongnu.org; Thu, 06 May 2021 09:41:11 -0400 Received: from indium.canonical.com ([91.189.90.7]:41886) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_128_GCM_SHA256:128) (Exim 4.90_1) (envelope-from ) id 1leeFZ-00014B-2S for qemu-devel@nongnu.org; Thu, 06 May 2021 09:41:11 -0400 Received: from loganberry.canonical.com ([91.189.90.37]) by indium.canonical.com with esmtp (Exim 4.93 #5 (Debian)) id 1leeFX-0001uZ-P5 for ; Thu, 06 May 2021 13:41:07 +0000 Received: from loganberry.canonical.com (localhost [127.0.0.1]) by loganberry.canonical.com (Postfix) with ESMTP id BCB812E802E for ; Thu, 6 May 2021 13:41:07 +0000 (UTC) MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: quoted-printable Date: Thu, 06 May 2021 13:33:29 -0000 From: Thomas Huth <1875702@bugs.launchpad.net> To: qemu-devel@nongnu.org X-Launchpad-Notification-Type: bug X-Launchpad-Bug: product=qemu; status=Incomplete; importance=Undecided; assignee=Laurent@vivier.eu; X-Launchpad-Bug-Tags: linux-user X-Launchpad-Bug-Information-Type: Public X-Launchpad-Bug-Private: no X-Launchpad-Bug-Security-Vulnerability: no X-Launchpad-Bug-Commenters: agl th-huth X-Launchpad-Bug-Reporter: agl (agl) X-Launchpad-Bug-Modifier: Thomas Huth (th-huth) References: <158809456539.8338.16342287412940632416.malonedeb@chaenomeles.canonical.com> Message-Id: <162030800998.6598.8113594581143069191.malone@wampee.canonical.com> Subject: [Bug 1875702] Re: madvise reports success, but doesn't implement WIPEONFORK. X-Launchpad-Message-Rationale: Subscriber (QEMU) @qemu-devel-ml X-Launchpad-Message-For: qemu-devel-ml Precedence: bulk X-Generated-By: Launchpad (canonical.com); Revision="d6ba96cccb3d3e356754af3137c6128a6c17e2a8"; Instance="production" X-Launchpad-Hash: 79f5e3acfad243e9d916ef63702cfc6749b47ad7 Received-SPF: none client-ip=91.189.90.7; envelope-from=bounces@canonical.com; helo=indium.canonical.com X-Spam_score_int: -65 X-Spam_score: -6.6 X-Spam_bar: ------ X-Spam_report: (-6.6 / 5.0 requ) BAYES_00=-1.9, HEADER_FROM_DIFFERENT_DOMAINS=0.248, RCVD_IN_DNSWL_HI=-5, RCVD_IN_MSPIKE_H3=0.001, RCVD_IN_MSPIKE_WL=0.001, SPF_HELO_NONE=0.001, SPF_NONE=0.001 autolearn=ham autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.23 List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Reply-To: Bug 1875702 <1875702@bugs.launchpad.net> Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" The QEMU project is currently moving its bug tracking to another system. For this we need to know which bugs are still valid and which could be closed already. Thus we are setting older bugs to "Incomplete" now. If you still think this bug report here is valid, then please switch the state back to "New" within the next 60 days, otherwise this report will be marked as "Expired". Or please mark it as "Fix Released" if the problem has been solved with a newer version of QEMU already. Thank you and sorry for the inconvenience. ** Changed in: qemu Status: New =3D> Incomplete ** Tags added: linux-user -- = You received this bug notification because you are a member of qemu- devel-ml, which is subscribed to QEMU. https://bugs.launchpad.net/bugs/1875702 Title: madvise reports success, but doesn't implement WIPEONFORK. Status in QEMU: Incomplete Bug description: The implementation of madvise (linux-user/syscall.c:11331, tag v5.0.0-rc4) always returns zero (i.e. success). However, an application requesting (at least) MADV_WIPEONFORK may need to know whether the call was actually successful. If not (because the kernel doesn't support WIPEONFORK) then it will need to take other measures to provide fork-safety (such as drawing entropy from the kernel in every case). But, if the application believes that WIPEONFORK is supported (because madvise returned zero), but it actually isn't (as in qemu), then it may forego those protections on the assumption that WIPEONFORK will provide fork-safety. Roughly, the comment in qemu that says "This is a hint, so ignoring and returning success is ok." is no longer accurate in the presence of MADV_WIPEONFORK. (This is not purely academic: BoringSSL is planning on acting in this way. We found the qemu behaviour in pre-release testing and are planning on making an madvise call with advice=3D-1 first to test whether unknown advice values actually produce EINVAL.) 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