From nobody Mon Feb 9 18:44:29 2026 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; 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; dmarc=fail(p=none dis=none) header.from=redhat.com ARC-Seal: i=1; a=rsa-sha256; t=1566409109; cv=none; d=zoho.com; s=zohoarc; b=GZbY2K058pRc9Tsu+Nkn/8ciseK/j1Asiw+1OyRJH4xS3XQY2nAL6gjkhZS2DpEO3kkBFalG9Kw5mkgy4ohe0bX8ilB1DdG2iwoQwBFk5FxWo/8Fl3qFzEaYBc8hFA368D7l8mpezDKabKSf8Nr8ecNZdq142xTVKo/OPxIAUsg= ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=zoho.com; s=zohoarc; t=1566409109; h=Cc:Date:From:In-Reply-To:List-Subscribe:List-Post:List-Id:List-Archive:List-Help:List-Unsubscribe:Message-ID:References:Sender:Subject:To:ARC-Authentication-Results; bh=Of0lmw/xYEFMyObyQUHOy2BHTAMgM6Twz2t+HDawnOU=; b=AH9KVxycKn9ViXLhEpRL2mfMywr5ukTlHjaTfcKeO8kQbWgGRUp9cFrZ45sJw+pivYJrKLRzC7AF/M4WHvOF65eTY7QkWsqtHzdWZXZB22VbAEo0njCzBW/HA9agTjVCS6VjoaS/82dwI2jD9bI2HLp0a8dCyc4A+VuQRzF0mTc= ARC-Authentication-Results: i=1; mx.zoho.com; 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; dmarc=fail header.from= (p=none dis=none) header.from= Return-Path: Received: from lists.gnu.org (lists.gnu.org [209.51.188.17]) by mx.zohomail.com with SMTPS id 1566409109017423.62202266819656; Wed, 21 Aug 2019 10:38:29 -0700 (PDT) Received: from localhost ([::1]:51192 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1i0UZ1-0002fJ-Bj for importer@patchew.org; Wed, 21 Aug 2019 13:38:27 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]:40455) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1i0UPp-0007HX-Uq for qemu-devel@nongnu.org; Wed, 21 Aug 2019 13:28:59 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1i0UPn-0005c5-E7 for qemu-devel@nongnu.org; Wed, 21 Aug 2019 13:28:57 -0400 Received: from mx1.redhat.com ([209.132.183.28]:57480) by eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1i0UPn-0005bQ-1t for qemu-devel@nongnu.org; Wed, 21 Aug 2019 13:28:55 -0400 Received: from smtp.corp.redhat.com (int-mx02.intmail.prod.int.phx2.redhat.com [10.5.11.12]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id 33FB4A2F6B6; Wed, 21 Aug 2019 17:28:54 +0000 (UTC) Received: from 640k.localdomain.com (ovpn-112-20.ams2.redhat.com [10.36.112.20]) by smtp.corp.redhat.com (Postfix) with ESMTP id CC03860E1C; Wed, 21 Aug 2019 17:28:52 +0000 (UTC) From: Paolo Bonzini To: qemu-devel@nongnu.org Date: Wed, 21 Aug 2019 19:28:21 +0200 Message-Id: <1566408501-48680-14-git-send-email-pbonzini@redhat.com> In-Reply-To: <1566408501-48680-1-git-send-email-pbonzini@redhat.com> References: <1566408501-48680-1-git-send-email-pbonzini@redhat.com> X-Scanned-By: MIMEDefang 2.79 on 10.5.11.12 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.6.2 (mx1.redhat.com [10.5.110.68]); Wed, 21 Aug 2019 17:28:54 +0000 (UTC) X-detected-operating-system: by eggs.gnu.org: GNU/Linux 2.2.x-3.x [generic] X-Received-From: 209.132.183.28 Subject: [Qemu-devel] [PULL 13/13] char-socket: Lock tcp_chr_disconnect() and socket_reconnect_timeout() X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.23 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Andrey Shinkevich , Alberto Garcia Errors-To: qemu-devel-bounces+importer=patchew.org@nongnu.org Sender: "Qemu-devel" Content-Transfer-Encoding: quoted-printable MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" From: Alberto Garcia 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 Signed-off-by: Andrey Shinkevich Message-Id: <1565625509-404969-3-git-send-email-andrey.shinkevich@virtuozzo= .com> Signed-off-by: Paolo Bonzini --- chardev/char-socket.c | 16 +++++++++++++--- 1 file changed, 13 insertions(+), 3 deletions(-) diff --git a/chardev/char-socket.c b/chardev/char-socket.c index 7ca5d97..03f0340 100644 --- a/chardev/char-socket.c +++ b/chardev/char-socket.c @@ -150,7 +150,7 @@ 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) @@ -174,7 +174,7 @@ 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 */ } @@ -469,8 +469,9 @@ static void update_disconnected_filename(SocketChardev = *s) /* 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; @@ -490,6 +491,13 @@ static void tcp_chr_disconnect(Chardev *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); @@ -1131,8 +1139,10 @@ 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 1.8.3.1