From nobody Sun Nov 9 14:50:02 2025 Delivered-To: importer@patchew.org Received-SPF: pass (zoho.com: domain of gnu.org designates 209.51.188.17 as permitted sender) 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=pass (zoho.com: domain of gnu.org designates 209.51.188.17 as permitted sender) smtp.mailfrom=qemu-devel-bounces+importer=patchew.org@nongnu.org Return-Path: Received: from lists.gnu.org (lists.gnu.org [209.51.188.17]) by mx.zohomail.com with SMTPS id 1550843540090332.72818307596106; Fri, 22 Feb 2019 05:52:20 -0800 (PST) Received: from localhost ([127.0.0.1]:51008 helo=lists.gnu.org) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1gxBFQ-0001kd-VI for importer@patchew.org; Fri, 22 Feb 2019 08:52:16 -0500 Received: from eggs.gnu.org ([209.51.188.92]:55267) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1gxBBX-0007Kf-KQ for qemu-devel@nongnu.org; Fri, 22 Feb 2019 08:48:19 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1gxBBV-0001jG-9E for qemu-devel@nongnu.org; Fri, 22 Feb 2019 08:48:15 -0500 Received: from fanzine.igalia.com ([91.117.99.155]:56218) by eggs.gnu.org with esmtps (TLS1.0:RSA_AES_128_CBC_SHA1:16) (Exim 4.71) (envelope-from ) id 1gxBBU-0000ic-GP for qemu-devel@nongnu.org; Fri, 22 Feb 2019 08:48:13 -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 1gxBAX-0007ys-7R; Fri, 22 Feb 2019 14:47:13 +0100 Received: from berto by perseus.local with local (Exim 4.89) (envelope-from ) id 1gxBAJ-0006PT-Cj; Fri, 22 Feb 2019 15:46:59 +0200 DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=igalia.com; s=20170329; h=References:In-Reply-To:References:In-Reply-To:Message-Id:Date:Subject:Cc:To:From; bh=wwwYObyQQglCF+PKULsz7D73vI/9oKchURnKdOTgEeM=; b=iAo6uzkZMjKd3j9SAiADjdCbUBYrn+jOrIblIJXrEgcTQTTW/F+w9zCejWH4Tzf03VTptLNBZGJJ4/nqborZCoo+dnmF9pDtsdbREJlklm6yts4muu71e3OiL0TaGoiNsWqiq4KwAboyT7ukGAhR/Se2Ce18HHE3ixpO5/+L6YlkSQjleu6qEVWNYmeE93DQUFrCjHlPt2Uie+ze2gk/n2nywWvyYWZLoJYO5MyKt7s7dRJy43oWKzV6L9KfDMt1RB0YUWMilhiMNGFNdwOoKJj31BizwiNt/YATOJBbaZXCQnj9uh5EHIiECms6tLyYdRA9/0nBv1bnWVenLrfbog==; From: Alberto Garcia To: qemu-devel@nongnu.org Date: Fri, 22 Feb 2019 15:46:26 +0200 Message-Id: <48f7e50413f6f222acb1bf3a9de773e387a2855a.1550842915.git.berto@igalia.com> X-Mailer: git-send-email 2.11.0 In-Reply-To: References: In-Reply-To: References: 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] [PATCH v3 3/3] char-socket: Lock tcp_chr_disconnect() and socket_reconnect_timeout() 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: Paolo Bonzini , Alberto Garcia , =?UTF-8?q?Marc-Andr=C3=A9=20Lureau?= 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 This patch adds a lock to protect tcp_chr_disconnect() and socket_reconnect_timeout() Signed-off-by: Alberto Garcia Reviewed-by: Daniel P. Berrang=C3=A9 --- chardev/char-socket.c | 25 +++++++++++++++++++++---- 1 file changed, 21 insertions(+), 4 deletions(-) diff --git a/chardev/char-socket.c b/chardev/char-socket.c index 4fcdd8aedd..94522777dc 100644 --- a/chardev/char-socket.c +++ b/chardev/char-socket.c @@ -148,7 +148,7 @@ static void tcp_chr_accept(QIONetListener *listener, void *opaque); =20 static int tcp_chr_read_poll(void *opaque); -static void tcp_chr_disconnect(Chardev *chr); +static void tcp_chr_disconnect_locked(Chardev *chr); =20 /* Called with chr_write_lock held. */ static int tcp_chr_write(Chardev *chr, const uint8_t *buf, int len) @@ -172,7 +172,7 @@ 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) { - tcp_chr_disconnect(chr); + tcp_chr_disconnect_locked(chr); return len; } /* else let the read handler finish it properly */ } @@ -464,11 +464,19 @@ static void update_disconnected_filename(SocketCharde= v *s) } } =20 +static gboolean tcp_chr_be_event_closed(gpointer opaque) +{ + Chardev *chr =3D opaque; + qemu_chr_be_event(chr, CHR_EVENT_CLOSED); + return FALSE; +} + /* NB may be called even if tcp_chr_connect has not been * reached, due to TLS or telnet initialization failure, * so can *not* assume s->state =3D=3D TCP_CHARDEV_STATE_CONNECTED + * This must be called with chr->chr_write_lock held. */ -static void tcp_chr_disconnect(Chardev *chr) +static void tcp_chr_disconnect_locked(Chardev *chr) { SocketChardev *s =3D SOCKET_CHARDEV(chr); bool emit_close =3D s->state =3D=3D TCP_CHARDEV_STATE_CONNECTED; @@ -481,13 +489,20 @@ static void tcp_chr_disconnect(Chardev *chr) } update_disconnected_filename(s); if (emit_close) { - qemu_chr_be_event(chr, CHR_EVENT_CLOSED); + qemu_idle_add(tcp_chr_be_event_closed, chr, chr->gcontext); } if (s->reconnect_time) { qemu_chr_socket_restart_timer(chr); } } =20 +static void tcp_chr_disconnect(Chardev *chr) +{ + qemu_mutex_lock(&chr->chr_write_lock); + tcp_chr_disconnect_locked(chr); + qemu_mutex_unlock(&chr->chr_write_lock); +} + static gboolean tcp_chr_read(QIOChannel *chan, GIOCondition cond, void *op= aque) { Chardev *chr =3D CHARDEV(opaque); @@ -1128,8 +1143,10 @@ static gboolean socket_reconnect_timeout(gpointer op= aque) Chardev *chr =3D CHARDEV(opaque); SocketChardev *s =3D SOCKET_CHARDEV(opaque); =20 + qemu_mutex_lock(&chr->chr_write_lock); g_source_unref(s->reconnect_timer); s->reconnect_timer =3D NULL; + qemu_mutex_unlock(&chr->chr_write_lock); =20 if (chr->be_open) { return false; --=20 2.11.0