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=-2.2 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_SANE_1 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 7C327C7618F for ; Fri, 19 Jul 2019 17:07:02 +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 53F592084D for ; Fri, 19 Jul 2019 17:07:02 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 53F592084D Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=redhat.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Received: from localhost ([::1]:47182 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.86_2) (envelope-from ) id 1hoWLV-0003jJ-KD for qemu-devel@archiver.kernel.org; Fri, 19 Jul 2019 13:07:01 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]:50574) by lists.gnu.org with esmtp (Exim 4.86_2) (envelope-from ) id 1hoWLL-0003Hi-9F for qemu-devel@nongnu.org; Fri, 19 Jul 2019 13:06:52 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1hoWLI-0005Eb-Rv for qemu-devel@nongnu.org; Fri, 19 Jul 2019 13:06:51 -0400 Received: from mx1.redhat.com ([209.132.183.28]:39934) by eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1hoWLE-0005C4-Fq; Fri, 19 Jul 2019 13:06:45 -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 081F63001443; Fri, 19 Jul 2019 17:06:42 +0000 (UTC) Received: from [10.3.116.46] (ovpn-116-46.phx2.redhat.com [10.3.116.46]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 43C1461369; Fri, 19 Jul 2019 17:06:41 +0000 (UTC) To: qemu-devel@nongnu.org References: <20190719150313.29198-1-eblake@redhat.com> From: Eric Blake Openpgp: preference=signencrypt Autocrypt: addr=eblake@redhat.com; keydata= xsBNBEvHyWwBCACw7DwsQIh0kAbUXyqhfiKAKOTVu6OiMGffw2w90Ggrp4bdVKmCaEXlrVLU xphBM8mb+wsFkU+pq9YR621WXo9REYVIl0FxKeQo9dyQBZ/XvmUMka4NOmHtFg74nvkpJFCD TUNzmqfcjdKhfFV0d7P/ixKQeZr2WP1xMcjmAQY5YvQ2lUoHP43m8TtpB1LkjyYBCodd+LkV GmCx2Bop1LSblbvbrOm2bKpZdBPjncRNob73eTpIXEutvEaHH72LzpzksfcKM+M18cyRH+nP sAd98xIbVjm3Jm4k4d5oQyE2HwOur+trk2EcxTgdp17QapuWPwMfhaNq3runaX7x34zhABEB AAHNHkVyaWMgQmxha2UgPGVibGFrZUByZWRoYXQuY29tPsLAegQTAQgAJAIbAwULCQgHAwUV CgkICwUWAgMBAAIeAQIXgAUCS8fL9QIZAQAKCRCnoWtKJSdDahBHCACbl/5FGkUqJ89GAjeX RjpAeJtdKhujir0iS4CMSIng7fCiGZ0fNJCpL5RpViSo03Q7l37ss+No+dJI8KtAp6ID+PMz wTJe5Egtv/KGUKSDvOLYJ9WIIbftEObekP+GBpWP2+KbpADsc7EsNd70sYxExD3liwVJYqLc Rw7so1PEIFp+Ni9A1DrBR5NaJBnno2PHzHPTS9nmZVYm/4I32qkLXOcdX0XElO8VPDoVobG6 gELf4v/vIImdmxLh/w5WctUpBhWWIfQDvSOW2VZDOihm7pzhQodr3QP/GDLfpK6wI7exeu3P pfPtqwa06s1pae3ad13mZGzkBdNKs1HEm8x6zsBNBEvHyWwBCADGkMFzFjmmyqAEn5D+Mt4P zPdO8NatsDw8Qit3Rmzu+kUygxyYbz52ZO40WUu7EgQ5kDTOeRPnTOd7awWDQcl1gGBXgrkR pAlQ0l0ReO57Q0eglFydLMi5bkwYhfY+TwDPMh3aOP5qBXkm4qIYSsxb8A+i00P72AqFb9Q7 3weG/flxSPApLYQE5qWGSXjOkXJv42NGS6o6gd4RmD6Ap5e8ACo1lSMPfTpGzXlt4aRkBfvb NCfNsQikLZzFYDLbQgKBA33BDeV6vNJ9Cj0SgEGOkYyed4I6AbU0kIy1hHAm1r6+sAnEdIKj cHi3xWH/UPrZW5flM8Kqo14OTDkI9EtlABEBAAHCwF8EGAEIAAkFAkvHyWwCGwwACgkQp6Fr SiUnQ2q03wgAmRFGDeXzc58NX0NrDijUu0zx3Lns/qZ9VrkSWbNZBFjpWKaeL1fdVeE4TDGm I5mRRIsStjQzc2R9b+2VBUhlAqY1nAiBDv0Qnt+9cLiuEICeUwlyl42YdwpmY0ELcy5+u6wz mK/jxrYOpzXKDwLq5k4X+hmGuSNWWAN3gHiJqmJZPkhFPUIozZUCeEc76pS/IUN72NfprZmF Dp6/QDjDFtfS39bHSWXKVZUbqaMPqlj/z6Ugk027/3GUjHHr8WkeL1ezWepYDY7WSoXwfoAL 2UXYsMAr/uUncSKlfjvArhsej0S4zbqim2ZY6S8aRWw94J3bSvJR+Nwbs34GPTD4Pg== Organization: Red Hat, Inc. Message-ID: <364e140d-9860-6b6e-672b-5765f668ac47@redhat.com> Date: Fri, 19 Jul 2019 12:06:40 -0500 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.7.0 MIME-Version: 1.0 In-Reply-To: <20190719150313.29198-1-eblake@redhat.com> Content-Type: multipart/signed; micalg=pgp-sha256; protocol="application/pgp-signature"; boundary="7OkKolVctZPZCrrj2OSc0X9uYwLr5h1us" X-Scanned-By: MIMEDefang 2.79 on 10.5.11.11 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.43]); Fri, 19 Jul 2019 17:06:42 +0000 (UTC) X-detected-operating-system: by eggs.gnu.org: GNU/Linux 2.2.x-3.x [generic] X-Received-From: 209.132.183.28 Subject: Re: [Qemu-devel] [PATCH] nbd: Initialize reply on failure X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.23 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Kevin Wolf , Andrey Shinkevich , Thomas Huth , "open list:Network Block Dev..." , Max Reitz Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" This is an OpenPGP/MIME signed message (RFC 4880 and 3156) --7OkKolVctZPZCrrj2OSc0X9uYwLr5h1us Content-Type: multipart/mixed; boundary="TD0KOCgGZcwQsk6UpxrViG9wlCdR9fqXt"; protected-headers="v1" From: Eric Blake To: qemu-devel@nongnu.org Cc: Kevin Wolf , Andrey Shinkevich , Thomas Huth , "open list:Network Block Dev..." , Max Reitz Message-ID: <364e140d-9860-6b6e-672b-5765f668ac47@redhat.com> Subject: Re: [Qemu-devel] [PATCH] nbd: Initialize reply on failure References: <20190719150313.29198-1-eblake@redhat.com> In-Reply-To: <20190719150313.29198-1-eblake@redhat.com> --TD0KOCgGZcwQsk6UpxrViG9wlCdR9fqXt Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: quoted-printable On 7/19/19 10:03 AM, Eric Blake wrote: > We've had two separate reports of a caller running into use of > uninitialized data if s->quit is set (one detected by gcc -O3, another > by valgrind), due to checking 'nbd_reply_is_simple(reply) || s->quit' > in the wrong order. Rather than chasing down which callers need to > pre-initialize reply, it's easier to guarantee that reply will always > be set by nbd_co_receive_one_chunk() even on failure. >=20 I'm adding: The bug is harmless (the only time uninitialized use is possible is if s->quit is set, so the conditional resolves to the same branch regardless of the contents of reply), but was introduced in commit 65e01d= 47. --=20 Eric Blake, Principal Software Engineer Red Hat, Inc. +1-919-301-3226 Virtualization: qemu.org | libvirt.org --TD0KOCgGZcwQsk6UpxrViG9wlCdR9fqXt-- --7OkKolVctZPZCrrj2OSc0X9uYwLr5h1us Content-Type: application/pgp-signature; name="signature.asc" Content-Description: OpenPGP digital signature Content-Disposition: attachment; filename="signature.asc" -----BEGIN PGP SIGNATURE----- iQEzBAEBCAAdFiEEccLMIrHEYCkn0vOqp6FrSiUnQ2oFAl0x+KAACgkQp6FrSiUn Q2oTMwgAlRVMkDzLrnBk/aCslKeWwOZ7G2pNcPDkkLQkjk2StkK/ymahCzk1BY/v R1HY6oBD3lWdl14jxqoBCjyae/VZNUgaf8cFZSgYVjeVHsjIfOcjVdsQam7SPu0F N25q8L4SbNI4GPKl58cD5zdGe7FpnG7i+kqd8h6AOtHN9UFy04elT+QxrdeKfRzz bplgWSfMNF4dkEJ/EmgCoIIjyZRPx7sUcuUaCk7TNPWIni+7S/a7EkdiUcfWcRGo IrJHXauvEYVY7RkVQyihTiCQ3hDqJEzof3xxIvv2giSTjtpUTnWoiCqAd699Ce8S b23b9ApL8ky0smyyq4ukZTrqUrAk0A== =U+uE -----END PGP SIGNATURE----- --7OkKolVctZPZCrrj2OSc0X9uYwLr5h1us--