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 D66FCC54756 for ; Mon, 19 May 2025 10:50:17 +0000 (UTC) Received: from localhost ([::1] helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1uGy4O-0004ex-RF; Mon, 19 May 2025 06:50:08 -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 1uGy4M-0004el-3Q for qemu-devel@nongnu.org; Mon, 19 May 2025 06:50:06 -0400 Received: from us-smtp-delivery-124.mimecast.com ([170.10.129.124]) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1uGy4I-0001G9-NS for qemu-devel@nongnu.org; Mon, 19 May 2025 06:50:05 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1747651797; 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=xTn6bni0o1Yo/KduYnhokf80jbZXIW+ZD1FyX+562fc=; b=TwTcnNA98D1iYzmPgQJUAzTVdJYv01o+rpbg+mPd5Gy/IgmzF/zivmZAk9R/ZJGKXU+H8I 5goB0pXkmWmivFdk1p87gpvF1N3F90/Aehjn3xNwRbXQG6Z4SLNhF/1TqxFEHMVhHNY0aS VqS6sDwEiqWUj/LuZlk7EEymdQWQneY= Received: from mx-prod-mc-02.mail-002.prod.us-west-2.aws.redhat.com (ec2-54-186-198-63.us-west-2.compute.amazonaws.com [54.186.198.63]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_256_GCM_SHA384) id us-mta-401-PGopqNDnPnuk0YL2SYeKPg-1; Mon, 19 May 2025 06:49:54 -0400 X-MC-Unique: PGopqNDnPnuk0YL2SYeKPg-1 X-Mimecast-MFC-AGG-ID: PGopqNDnPnuk0YL2SYeKPg_1747651793 Received: from mx-prod-int-08.mail-002.prod.us-west-2.aws.redhat.com (mx-prod-int-08.mail-002.prod.us-west-2.aws.redhat.com [10.30.177.111]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits) server-digest SHA256) (No client certificate requested) by mx-prod-mc-02.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTPS id 642171956086; Mon, 19 May 2025 10:49:53 +0000 (UTC) Received: from redhat.com (unknown [10.42.28.50]) by mx-prod-int-08.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTPS id 4CBC018001D8; Mon, 19 May 2025 10:49:50 +0000 (UTC) Date: Mon, 19 May 2025 11:49:47 +0100 From: Daniel =?utf-8?B?UC4gQmVycmFuZ8Op?= To: Fabiano Rosas Cc: qemu-devel@nongnu.org, marcandre.lureau@redhat.com, pbonzini@redhat.com Subject: Re: [PATCH 1/4] chardev: Fix QIOChannel refcount Message-ID: References: <20250515222014.4161-1-farosas@suse.de> <20250515222014.4161-2-farosas@suse.de> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <20250515222014.4161-2-farosas@suse.de> User-Agent: Mutt/2.2.14 (2025-02-20) X-Scanned-By: MIMEDefang 3.4.1 on 10.30.177.111 Received-SPF: pass client-ip=170.10.129.124; envelope-from=berrange@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-Spam_score_int: -31 X-Spam_score: -3.2 X-Spam_bar: --- X-Spam_report: (-3.2 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.13, 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_H5=-1, RCVD_IN_MSPIKE_WL=-0.01, RCVD_IN_VALIDITY_CERTIFIED_BLOCKED=0.001, RCVD_IN_VALIDITY_RPBL_BLOCKED=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: , Reply-To: Daniel =?utf-8?B?UC4gQmVycmFuZ8Op?= Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org On Thu, May 15, 2025 at 07:20:11PM -0300, Fabiano Rosas wrote: > The IOWatchPoll holds a reference to the iochannel while the "child" > source (iwp->src) is removed from the context and freed. Freeing the > source leads to the iochannel being also freed at > qio_channel_fd_source_finalize(). > > Later, io_watch_poll_prepare() tries to create another source with the > same iochannel and hits an use after free: > > ==8241==ERROR: AddressSanitizer: heap-use-after-free on address 0x514000000040 > READ of size 8 at 0x514000000040 thread T2 > #0 0x561c2d272fcd in object_get_class ../qom/object.c:1043:17 > #1 0x561c2d338f84 in QIO_CHANNEL_GET_CLASS include/io/channel.h:29:1 > #2 0x561c2d33b26f in qio_channel_create_watch ../io/channel.c:388:30 > #3 0x561c2d2f0993 in io_watch_poll_prepare ../chardev/char-io.c:65:20 > ... > > 0x514000000040 is located 0 bytes inside of 392-byte region [0x514000000040,0x5140000001c8) > freed by thread T2 here: > #0 0x561c2d2319a5 in free > #1 0x7fb2c0926638 in g_free > #2 0x561c2d276507 in object_finalize ../qom/object.c:734:9 > #3 0x561c2d271d0d in object_unref ../qom/object.c:1231:9 > #4 0x561c2d32ef1d in qio_channel_fd_source_finalize ../io/channel-watch.c:95:5 > #5 0x7fb2c091d124 in g_source_unref_internal ../glib/gmain.c:2298 > #6 0x561c2d2f0b6c in io_watch_poll_prepare ../chardev/char-io.c:71:9 > ... > > previously allocated by thread T3 (connect) here: > #0 0x561c2d231c69 in malloc > #1 0x7fb2c0926518 in g_malloc > #2 0x561c2d27246e in object_new_with_type ../qom/object.c:767:15 > #3 0x561c2d272530 in object_new ../qom/object.c:789:12 > #4 0x561c2d320193 in qio_channel_socket_new ../io/channel-socket.c:64:31 > #5 0x561c2d308013 in tcp_chr_connect_client_async ../chardev/char-socket.c:1181:12 > #6 0x561c2d3002e7 in qmp_chardev_open_socket_client ../chardev/char-socket.c:1281:9 > ... > > Fix the issue by incrementing the iochannel reference count when the > IOWatchPoll takes a reference and decrementing when it is finalized. > > Signed-off-by: Fabiano Rosas > --- > chardev/char-io.c | 5 +++++ > 1 file changed, 5 insertions(+) Reviewed-by: Daniel P. Berrangé 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 :|