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 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 78515C43334 for ; Wed, 20 Jul 2022 09:05:51 +0000 (UTC) Received: from localhost ([::1]:39826 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1oE5eQ-0001wr-5P for qemu-devel@archiver.kernel.org; Wed, 20 Jul 2022 05:05:50 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]:57628) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1oE5Zn-00066U-EN for qemu-devel@nongnu.org; Wed, 20 Jul 2022 05:01:15 -0400 Received: from us-smtp-delivery-124.mimecast.com ([170.10.133.124]:46716) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1oE5Zj-0000jb-La for qemu-devel@nongnu.org; Wed, 20 Jul 2022 05:01:01 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1658307658; h=from:from:reply-to: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=mMNVs/SOALWTpUJy5SOSKs4X9WPKAe79d2xdGVHf2H4=; b=UB2B0w2PDbaTzRGxmhFqJSG6HCe8qgc+qHu8dPikIl+nP+zQbqD8hbg9dyf6BeVkV24F6g Rb2hvdBBHnfVAQi5Y4DaAi1tTPrDGYMgKJm5QRWKplqKjQPfGT5cxKjQEN2HarMvQrnCPg 6vhx+u7vs7CR4BObtpcIhP8vkltfqng= Received: from mimecast-mx02.redhat.com (mx3-rdu2.redhat.com [66.187.233.73]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id us-mta-658-mTyYwI2dOw-FefVEhnPH8A-1; Wed, 20 Jul 2022 05:00:49 -0400 X-MC-Unique: mTyYwI2dOw-FefVEhnPH8A-1 Received: from smtp.corp.redhat.com (int-mx09.intmail.prod.int.rdu2.redhat.com [10.11.54.9]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx02.redhat.com (Postfix) with ESMTPS id 1960D3C138A3; Wed, 20 Jul 2022 09:00:49 +0000 (UTC) Received: from redhat.com (unknown [10.33.36.41]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 03D1F492C3B; Wed, 20 Jul 2022 09:00:47 +0000 (UTC) Date: Wed, 20 Jul 2022 10:00:45 +0100 From: Daniel =?utf-8?B?UC4gQmVycmFuZ8Op?= To: "Wangjing(Hogan)" Cc: =?utf-8?Q?Marc-Andr=C3=A9?= Lureau , Markus Armbruster , QEMU , Paolo Bonzini , "Wangxin (Alexander)" Subject: Re: [PATCH v2] chardev: avoid use-after-free when client disconnect Message-ID: References: <30274fbaea9d437baff2d703a203f9a8@huawei.com> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <30274fbaea9d437baff2d703a203f9a8@huawei.com> User-Agent: Mutt/2.2.6 (2022-06-05) X-Scanned-By: MIMEDefang 2.85 on 10.11.54.9 Received-SPF: pass client-ip=170.10.133.124; envelope-from=berrange@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-Spam_score_int: -21 X-Spam_score: -2.2 X-Spam_bar: -- X-Spam_report: (-2.2 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.082, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_NONE=-0.0001, SPF_HELO_NONE=0.001, SPF_PASS=-0.001, T_SCC_BODY_TEXT_LINE=-0.01 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: , Reply-To: Daniel =?utf-8?B?UC4gQmVycmFuZ8Op?= Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" On Wed, Jul 20, 2022 at 08:55:46AM +0000, Wangjing(Hogan) wrote: > > > On Wed, Jul 20, 2022 at 11:36:07AM +0400, Marc-André Lureau wrote: > > > Hi > > > > > > On Wed, Jul 20, 2022 at 11:13 AM Hogan Wang via > > > > > > wrote: > > > > > > > IOWatchPoll object did not hold the @ioc and @src objects reference, > > > > then io_watch_poll_prepare execute in IO thread, if IOWatchPoll > > > > removed by mian thread, then io_watch_poll_prepare access @ioc or > > > > > > > > > > mian->main > > > > > > > > > > @src concurrently lead to coredump. > > > > > > > > In IO thread monitor scene, the IO thread used to accept client, > > > > receive qmp request and handle hung-up event. Main thread used to > > > > handle qmp request and send response, it will remove IOWatchPoll and > > > > free @ioc when send response fail, then cause use-after-free > > > > > > > > > > I wonder if we are misusing GSources in that case, by removing sources > > > from different threads.. Could you be more specific about the code > > > path that leads to that? > > > > It is permitted, but unfortunately every version of glib prior to 2.64 has a race condition that means you'll periodically get a use-after-free and a crash: > > > > https://gitlab.gnome.org/GNOME/glib/-/merge_requests/1358 > > > > Libvirt worked around this problem by not calling 'g_source_unref' > > directly, but instead have a helper that uses g_idle_add to delay the unref such that its guaranteed to happen inside the main event loop thread. > > > > So I'd like to know what version of glib Hogan is using > > I am using glib2-2.62.5 in test environment, so it's looks like a glib2 known issue. Hmm, actually the fix should have been backported into the 2.62.5 release according to this https://gitlab.gnome.org/GNOME/glib/-/merge_requests/1361 With regards, Daniel -- |: https://berrange.com -o- https://www.flickr.com/photos/dberrange :| |: https://libvirt.org -o- https://fstop138.berrange.com :| |: https://entangle-photo.org -o- https://www.instagram.com/dberrange :|