From patchwork Mon Feb 8 13:55:07 2016 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: =?utf-8?q?Daniel_P=2E_Berrang=C3=A9?= X-Patchwork-Id: 580289 Return-Path: X-Original-To: incoming@patchwork.ozlabs.org Delivered-To: patchwork-incoming@bilbo.ozlabs.org Received: from lists.gnu.org (lists.gnu.org [IPv6:2001:4830:134:3::11]) (using TLSv1 with cipher AES256-SHA (256/256 bits)) (No client certificate requested) by ozlabs.org (Postfix) with ESMTPS id 1E429140B0F for ; Tue, 9 Feb 2016 00:55:51 +1100 (AEDT) Received: from localhost ([::1]:44928 helo=lists.gnu.org) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1aSmI9-0005Ry-7s for incoming@patchwork.ozlabs.org; Mon, 08 Feb 2016 08:55:49 -0500 Received: from eggs.gnu.org ([2001:4830:134:3::10]:45942) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1aSmHe-0004lF-Fb for qemu-devel@nongnu.org; Mon, 08 Feb 2016 08:55:19 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1aSmHb-0007B8-4X for qemu-devel@nongnu.org; Mon, 08 Feb 2016 08:55:18 -0500 Received: from mx1.redhat.com ([209.132.183.28]:52387) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1aSmHa-0007Au-Vl; Mon, 08 Feb 2016 08:55:15 -0500 Received: from int-mx14.intmail.prod.int.phx2.redhat.com (int-mx14.intmail.prod.int.phx2.redhat.com [10.5.11.27]) by mx1.redhat.com (Postfix) with ESMTPS id 619B88E221; Mon, 8 Feb 2016 13:55:14 +0000 (UTC) Received: from t530wlan.home.berrange.com.com (vpn1-6-235.ams2.redhat.com [10.36.6.235]) by int-mx14.intmail.prod.int.phx2.redhat.com (8.14.4/8.14.4) with ESMTP id u18DtBDP002691; Mon, 8 Feb 2016 08:55:12 -0500 From: "Daniel P. Berrange" To: qemu-devel@nongnu.org Date: Mon, 8 Feb 2016 13:55:07 +0000 Message-Id: <1454939707-10869-1-git-send-email-berrange@redhat.com> X-Scanned-By: MIMEDefang 2.68 on 10.5.11.27 X-detected-operating-system: by eggs.gnu.org: GNU/Linux 3.x X-Received-From: 209.132.183.28 Cc: qemu-trivial@nongnu.org, Paolo Bonzini , Mark Cave-Ayland Subject: [Qemu-devel] [PATCH] char: fix repeated registration of tcp chardev I/O handlers X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.14 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: qemu-devel-bounces+incoming=patchwork.ozlabs.org@nongnu.org Sender: qemu-devel-bounces+incoming=patchwork.ozlabs.org@nongnu.org In previous commit: commit f2001a7e0555b66d6db25a3ff1801540814045bb Author: Daniel P. Berrange Date: Tue Jan 19 11:14:30 2016 +0000 char: don't assume telnet initialization will not block The code which writes the telnet initialization sequence moved to an event loop callback. If the TCP chardev is opened as a server in blocking mode (ie -serial telnet:0.0.0.0:3000,server,wait) this results in a state where the TCP chardev is connected, but not yet ready to send/recv data when virtual hardware is created. When the virtual hardware initialization registers its chardev callbacks, it triggers tcp_chr_update_read_handler, which will add I/O watches to the connection. When the telnet initialization finally runs, it will then call tcp_chr_connect to finish the connection setup. This will in turn add I/O watches to the connection too. There are now two sets of I/O watches registered on the same connection. This ultimately causes data loss on the connection, for example, when typing into the telnet console only every second byte is echoed back to the client. The same flaw can affect channels running with TLS encryption too, since they also have delayed connection setup completion. The fix is to update tcp_chr_update_read_handler so that it avoids registering watches if the connection is not fully setup yet. Signed-off-by: Daniel P. Berrange --- qemu-char.c | 4 ++++ 1 file changed, 4 insertions(+) diff --git a/qemu-char.c b/qemu-char.c index 927c47e..9060f8a 100644 --- a/qemu-char.c +++ b/qemu-char.c @@ -2856,6 +2856,10 @@ static void tcp_chr_update_read_handler(CharDriverState *chr) { TCPCharDriver *s = chr->opaque; + if (!s->connected) { + return; + } + remove_fd_in_watch(chr); if (s->ioc) { chr->fd_in_tag = io_add_watch_poll(s->ioc,