From patchwork Wed Sep 13 07:46:57 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Eric Auger X-Patchwork-Id: 13382559 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org 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 smtp.lore.kernel.org (Postfix) with ESMTPS id 276FDCA5501 for ; Wed, 13 Sep 2023 07:48:00 +0000 (UTC) Received: from localhost ([::1] helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1qgKah-0003Fq-Vq; Wed, 13 Sep 2023 03:47:16 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1qgKaf-0003FQ-TU for qemu-devel@nongnu.org; Wed, 13 Sep 2023 03:47:13 -0400 Received: from us-smtp-delivery-124.mimecast.com ([170.10.133.124]) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1qgKad-000630-J1 for qemu-devel@nongnu.org; Wed, 13 Sep 2023 03:47:13 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1694591223; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version: content-transfer-encoding:content-transfer-encoding; bh=I5eMpr2L+oDdbAVnMFYihTm1RKGCWAkzGk6JihsOgwQ=; b=gfVpklRWF9dnGo3ZjUOZ1OnGviTIquQfsGNjAQ2sx6CYWQ9QOYb5ap8lMGhIPSLt55qlOU t6cihi4KsXMBuawzNaXrDap+AtzEmCbCoWig7Y4PX9TaWieyPCWDTPPKfL38hL9XU4CoHA RhehwCoce2cMrF1tMf9ghgiX42CoY7Q= Received: from mimecast-mx02.redhat.com (mimecast-mx02.redhat.com [66.187.233.88]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id us-mta-554-qcWGqic5OH2ogHhqfJTogw-1; Wed, 13 Sep 2023 03:47:02 -0400 X-MC-Unique: qcWGqic5OH2ogHhqfJTogw-1 Received: from smtp.corp.redhat.com (int-mx05.intmail.prod.int.rdu2.redhat.com [10.11.54.5]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mimecast-mx02.redhat.com (Postfix) with ESMTPS id C4C128A12B9; Wed, 13 Sep 2023 07:47:01 +0000 (UTC) Received: from laptop.redhat.com (unknown [10.39.192.7]) by smtp.corp.redhat.com (Postfix) with ESMTP id 62617422E0; Wed, 13 Sep 2023 07:47:00 +0000 (UTC) From: Eric Auger To: eric.auger.pro@gmail.com, eric.auger@redhat.com, mst@redhat.com, qemu-devel@nongnu.org Cc: jasowang@redhat.com, lvivier@redhat.com Subject: [PATCH] vhost: Add a defensive check in vhost_commit against wrong deallocation Date: Wed, 13 Sep 2023 09:46:57 +0200 Message-ID: <20230913074657.523530-1-eric.auger@redhat.com> MIME-Version: 1.0 X-Scanned-By: MIMEDefang 3.1 on 10.11.54.5 Received-SPF: pass client-ip=170.10.133.124; envelope-from=eric.auger@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-Spam_score_int: -20 X-Spam_score: -2.1 X-Spam_bar: -- X-Spam_report: (-2.1 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.001, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_NONE=-0.0001, RCVD_IN_MSPIKE_H3=0.001, RCVD_IN_MSPIKE_WL=0.001, SPF_HELO_NONE=0.001, SPF_PASS=-0.001 autolearn=ham autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org In vhost_commit(), it may happen that dev->mem_sections and dev->tmp_sections are equal, in which case, unconditionally freeing old_sections at the end of the function will also free dev->mem_sections used on subsequent call leading to a segmentation fault. Check this situation before deallocating memory. Signed-off-by: Eric Auger Fixes: c44317efecb2 ("vhost: Build temporary section list and deref after commit") CC: QEMU Stable --- This SIGSEV condition can be reproduced with https://lore.kernel.org/all/20230904080451.424731-1-eric.auger@redhat.com/#r This is most probably happening in a situation where the memory API is used in a wrong manner but well. --- hw/virtio/vhost.c | 5 +++++ 1 file changed, 5 insertions(+) diff --git a/hw/virtio/vhost.c b/hw/virtio/vhost.c index e2f6ffb446..c02c599ef0 100644 --- a/hw/virtio/vhost.c +++ b/hw/virtio/vhost.c @@ -545,6 +545,11 @@ static void vhost_commit(MemoryListener *listener) dev->mem_sections = dev->tmp_sections; dev->n_mem_sections = dev->n_tmp_sections; + if (old_sections == dev->mem_sections) { + assert(n_old_sections == dev->n_mem_sections); + return; + } + if (dev->n_mem_sections != n_old_sections) { changed = true; } else {