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=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED 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 ED456C43331 for ; Thu, 26 Mar 2020 13:24:16 +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 B54D52073E for ; Thu, 26 Mar 2020 13:24:16 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="bDp5puXw" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org B54D52073E 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]:51484 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1jHSUZ-00077u-UE for qemu-devel@archiver.kernel.org; Thu, 26 Mar 2020 09:24:15 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]:54252) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1jHSTn-0005ot-CO for qemu-devel@nongnu.org; Thu, 26 Mar 2020 09:23:28 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1jHSTm-0002UL-CU for qemu-devel@nongnu.org; Thu, 26 Mar 2020 09:23:27 -0400 Received: from us-smtp-delivery-74.mimecast.com ([216.205.24.74]:29932) by eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1jHSTm-0002UF-1i for qemu-devel@nongnu.org; Thu, 26 Mar 2020 09:23:26 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1585229005; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=KAksK0cApWjz3rYuvl1Wzp9hhiFAIOZbGLE3FLHfEt8=; b=bDp5puXww+3glGJg/6ghgUwyd4sbk6pRipbwxj3XuO4gDlfxF/BgMc+8a+d0dZzOrO6I3H WSr46TH7kY/dBmDVv7HDiDNzWB+Lgemq9p/4e62eZR03cxTjJC37Fm4MR0Y0+9+h8p4h7J nbtrc9Uu28atOyMkKzC1QIeN5wbBpy4= Received: from mimecast-mx01.redhat.com (mimecast-mx01.redhat.com [209.132.183.4]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-151-2fY6K8pEN1yH4Uw4xWEJlg-1; Thu, 26 Mar 2020 09:23:24 -0400 X-MC-Unique: 2fY6K8pEN1yH4Uw4xWEJlg-1 Received: from smtp.corp.redhat.com (int-mx05.intmail.prod.int.phx2.redhat.com [10.5.11.15]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id 0D24E8010F2; Thu, 26 Mar 2020 13:23:23 +0000 (UTC) Received: from localhost (unknown [10.40.208.76]) by smtp.corp.redhat.com (Postfix) with ESMTP id E92FD5E008; Thu, 26 Mar 2020 13:23:18 +0000 (UTC) Date: Thu, 26 Mar 2020 14:23:17 +0100 From: Igor Mammedov To: Peter Maydell Subject: Re: acpi_pcihp_eject_slot() bug if passed 'slots == 0' Message-ID: <20200326142317.018c13e1@redhat.com> In-Reply-To: References: MIME-Version: 1.0 X-Scanned-By: MIMEDefang 2.79 on 10.5.11.15 X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit X-detected-operating-system: by eggs.gnu.org: GNU/Linux 2.2.x-3.x [generic] [fuzzy] X-Received-From: 216.205.24.74 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: QEMU Developers , "Michael S. Tsirkin" Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" On Thu, 26 Mar 2020 11:52:36 +0000 Peter Maydell wrote: > Hi; Coverity spots that if hw/acpi/pcihp.c:acpi_pcihp_eject_slot() > is passed a zero 'slots' argument then ctz32(slots) will return 32, > and then the code that does '1U << slot' is C undefined behaviour > because it's an oversized shift. (This is CID 1421896.) > > Since the pci_write() function in this file can call > acpi_pcihp_eject_slot() with an arbitrary value from the guest, > I think we need to handle 'slots == 0' safely. But what should > the behaviour be? it also uncovers a bug, where we are not able to eject slot 0 on bridge, can be reproduced with: -enable-kvm -m 4G -device pci-bridge,chassis_nr=1 -global PIIX4_PM.acpi-pci-hotplug-with-bridge-support=on -device virtio-net-pci,bus=pci.1,addr=0,id=netdev12 (monitor) device_del netdev12 (monitor) qtree # still shows the device reason is that acpi_pcihp_eject_slot() if (PCI_SLOT(dev->devfn) == slot) { # doesn't match (0 != 32) so device is not deleted > thanks > -- PMM >