From nobody Sun May 5 18:31:39 2024 Delivered-To: importer@patchew.org Received-SPF: temperror (zoho.com: Error in retrieving data from DNS) client-ip=209.51.188.17; envelope-from=qemu-devel-bounces+importer=patchew.org@nongnu.org; helo=lists.gnu.org; Authentication-Results: mx.zohomail.com; dkim=fail; spf=temperror (zoho.com: Error in retrieving data from DNS) smtp.mailfrom=qemu-devel-bounces+importer=patchew.org@nongnu.org Return-Path: Received: from lists.gnu.org (209.51.188.17 [209.51.188.17]) by mx.zohomail.com with SMTPS id 1549457155683402.81961096069006; Wed, 6 Feb 2019 04:45:55 -0800 (PST) Received: from localhost ([127.0.0.1]:49967 helo=lists.gnu.org) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1grMaG-0001mE-Ht for importer@patchew.org; Wed, 06 Feb 2019 07:45:44 -0500 Received: from eggs.gnu.org ([209.51.188.92]:45538) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1grMZE-000172-8Y for qemu-devel@nongnu.org; Wed, 06 Feb 2019 07:44:41 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1grMZB-0006pc-FW for qemu-devel@nongnu.org; Wed, 06 Feb 2019 07:44:39 -0500 Received: from fanzine.igalia.com ([91.117.99.155]:58108) by eggs.gnu.org with esmtps (TLS1.0:RSA_AES_128_CBC_SHA1:16) (Exim 4.71) (envelope-from ) id 1grMZ7-0006bS-L8 for qemu-devel@nongnu.org; Wed, 06 Feb 2019 07:44:35 -0500 Received: from 62-165-147-230.co.dnainternet.fi ([62.165.147.230] helo=perseus.local) by fanzine.igalia.com with esmtpsa (Cipher TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim) id 1grMYk-00006U-SL; Wed, 06 Feb 2019 13:44:10 +0100 Received: from berto by perseus.local with local (Exim 4.89) (envelope-from ) id 1grMYX-0003tm-OP; Wed, 06 Feb 2019 14:43:57 +0200 DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=igalia.com; s=20170329; h=Message-Id:Date:Subject:Cc:To:From; bh=sqLSPEh9mS0QkKvfysvsJq2X7F9n1ku+CfhJx1NGqyE=; b=e0647URSdfAxaplCMiw2TbxO8/r69eCCl7fPQip7xKHtQUffGaqObmx4MC/GwkQqeVBGNSOXDUvsW4SMuIGkF26vXSsAq8u1GiUZ48vTJ2vg3gTksSShPEe5H2ILxJdWhkHxH8PATJo2nveEBsjEsFCTZIWwI+BoDIi5AOhybP0rpyJxYOQh1n7TgqsEodO9Ffj854Shdr94sj6R3d8IgMpYYlQD3DJK8omK0QBvF/sgg2J4xEjaujA77hrkhchstMDMi6mHNFU4eZMyfh5GoVmXREQTonUf+rwgxq/jR95HRBiInVFAiG6yqQML9K9aT8wI7IeO2WaO9omKKeK80g==; From: Alberto Garcia To: qemu-devel@nongnu.org Date: Wed, 6 Feb 2019 14:43:45 +0200 Message-Id: <20190206124345.14942-1-berto@igalia.com> X-Mailer: git-send-email 2.11.0 X-detected-operating-system: by eggs.gnu.org: GNU/Linux 2.2.x-3.x (no timestamps) [generic] [fuzzy] X-Received-From: 91.117.99.155 Subject: [Qemu-devel] [RFC PATCH] char-socket: hold chr_write_lock during tcp_chr_free_connection() X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.21 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: =?UTF-8?q?Marc-Andr=C3=A9=20Lureau?= , Alberto Garcia , Paolo Bonzini Errors-To: qemu-devel-bounces+importer=patchew.org@nongnu.org Sender: "Qemu-devel" X-ZohoMail-DKIM: fail (Header signature does not verify) Content-Transfer-Encoding: quoted-printable MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" There's a race condition in which the tcp_chr_read() ioc handler can close a connection that is being written to from another thread. Running iotest 136 in a loop triggers this problem and crashes QEMU. (gdb) bt #0 0x00005558b842902d in object_get_class (obj=3D0x0) at qom/object.c:860 #1 0x00005558b84f92db in qio_channel_writev_full (ioc=3D0x0, iov=3D0x7ffc= 355decf0, niov=3D1, fds=3D0x0, nfds=3D0, errp=3D0x0) at io/channel.c:76 #2 0x00005558b84e0e9e in io_channel_send_full (ioc=3D0x0, buf=3D0x5558baf= 5beb0, len=3D138, fds=3D0x0, nfds=3D0) at chardev/char-io.c:123 #3 0x00005558b84e4a69 in tcp_chr_write (chr=3D0x5558ba460380, buf=3D0x555= 8baf5beb0 "...", len=3D138) at chardev/char-socket.c:135 #4 0x00005558b84dca55 in qemu_chr_write_buffer (s=3D0x5558ba460380, buf= =3D0x5558baf5beb0 "...", len=3D138, offset=3D0x7ffc355dedd0, write_all=3Dfa= lse) at chardev/char.c:112 #5 0x00005558b84dcbc2 in qemu_chr_write (s=3D0x5558ba460380, buf=3D0x5558= baf5beb0 "...", len=3D138, write_all=3Dfalse) at chardev/char.c:147 #6 0x00005558b84dfb26 in qemu_chr_fe_write (be=3D0x5558ba476610, buf=3D0x= 5558baf5beb0 "...", len=3D138) at chardev/char-fe.c:42 #7 0x00005558b8088c86 in monitor_flush_locked (mon=3D0x5558ba476610) at m= onitor.c:406 #8 0x00005558b8088e8c in monitor_puts (mon=3D0x5558ba476610, str=3D0x5558= ba921e49 "") at monitor.c:449 #9 0x00005558b8089178 in qmp_send_response (mon=3D0x5558ba476610, rsp=3D0= x5558bb161600) at monitor.c:498 #10 0x00005558b808920c in monitor_qapi_event_emit (event=3DQAPI_EVENT_SHUT= DOWN, qdict=3D0x5558bb161600) at monitor.c:526 #11 0x00005558b8089307 in monitor_qapi_event_queue_no_reenter (event=3DQAP= I_EVENT_SHUTDOWN, qdict=3D0x5558bb161600) at monitor.c:551 #12 0x00005558b80896c0 in qapi_event_emit (event=3DQAPI_EVENT_SHUTDOWN, qd= ict=3D0x5558bb161600) at monitor.c:626 #13 0x00005558b855f23b in qapi_event_send_shutdown (guest=3Dfalse, reason= =3DSHUTDOWN_CAUSE_HOST_QMP_QUIT) at qapi/qapi-events-run-state.c:43 #14 0x00005558b81911ef in qemu_system_shutdown (cause=3DSHUTDOWN_CAUSE_HOS= T_QMP_QUIT) at vl.c:1837 #15 0x00005558b8191308 in main_loop_should_exit () at vl.c:1885 #16 0x00005558b819140d in main_loop () at vl.c:1924 #17 0x00005558b8198c84 in main (argc=3D18, argv=3D0x7ffc355df3f8, envp=3D0= x7ffc355df490) at vl.c:4665 Signed-off-by: Alberto Garcia --- chardev/char-socket.c | 4 ++++ 1 file changed, 4 insertions(+) diff --git a/chardev/char-socket.c b/chardev/char-socket.c index eaa8e8b68f..47bef1d2bd 100644 --- a/chardev/char-socket.c +++ b/chardev/char-socket.c @@ -148,7 +148,9 @@ static int tcp_chr_write(Chardev *chr, const uint8_t *b= uf, int len) =20 if (ret < 0 && errno !=3D EAGAIN) { if (tcp_chr_read_poll(chr) <=3D 0) { + qemu_mutex_unlock(&chr->chr_write_lock); tcp_chr_disconnect(chr); + qemu_mutex_lock(&chr->chr_write_lock); return len; } /* else let the read handler finish it properly */ } @@ -449,7 +451,9 @@ static void tcp_chr_disconnect(Chardev *chr) SocketChardev *s =3D SOCKET_CHARDEV(chr); bool emit_close =3D s->connected; =20 + qemu_mutex_lock(&chr->chr_write_lock); tcp_chr_free_connection(chr); + qemu_mutex_unlock(&chr->chr_write_lock); =20 if (s->listener) { qio_net_listener_set_client_func_full(s->listener, tcp_chr_accept, --=20 2.11.0