From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:54015) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1emNgT-00022n-Qr for qemu-devel@nongnu.org; Thu, 15 Feb 2018 12:51:03 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1emNgP-0003KY-2A for qemu-devel@nongnu.org; Thu, 15 Feb 2018 12:51:01 -0500 Received: from mx3-rdu2.redhat.com ([66.187.233.73]:60016 helo=mx1.redhat.com) by eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1emNgO-0003Jh-SA for qemu-devel@nongnu.org; Thu, 15 Feb 2018 12:50:56 -0500 From: =?UTF-8?q?Daniel=20P=2E=20Berrang=C3=A9?= Date: Thu, 15 Feb 2018 17:50:39 +0000 Message-Id: <20180215175044.8159-3-berrange@redhat.com> In-Reply-To: <20180215175044.8159-1-berrange@redhat.com> References: <20180215175044.8159-1-berrange@redhat.com> Subject: [Qemu-devel] [PULL 2/7] io/channel-websock: handle continuous reads without any data List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: qemu-devel@nongnu.org Cc: Peter Maydell , Edgar Kaziakhmedov , "Daniel P . Berrange" From: Edgar Kaziakhmedov According to the current implementation of websocket protocol in QEMU, qio_channel_websock_handshake_io tries to read handshake from the channel to start communication over socket. But this approach doesn't cover scenario when socket was closed while handshaking. Therefore, if G_IO_IN is caught and qio_channel_read returns zero, error has to be set and connection has to be done. Such behaviour causes 100% CPU load in main QEMU loop, because main loop poll continues to receive and handle G_IO_IN events from websocket. Step to reproduce 100% CPU load: 1) start qemu with the simplest configuration $ qemu -vnc [::1]:1,websocket=7500 2) open any vnc listener (which doesn't follow websocket protocol) $ vncviewer :7500 3) kill listener 4) qemu main thread eats 100% CPU Signed-off-by: Edgar Kaziakhmedov Signed-off-by: Daniel P. Berrange --- io/channel-websock.c | 7 +++++-- 1 file changed, 5 insertions(+), 2 deletions(-) diff --git a/io/channel-websock.c b/io/channel-websock.c index 7fd6bb68ba..ec48a305f0 100644 --- a/io/channel-websock.c +++ b/io/channel-websock.c @@ -499,9 +499,12 @@ static int qio_channel_websock_handshake_read(QIOChannelWebsock *ioc, error_setg(errp, "End of headers not found in first 4096 bytes"); return 1; - } else { - return 0; + } else if (ret == 0) { + error_setg(errp, + "End of headers not found before connection closed"); + return -1; } + return 0; } *handshake_end = '\0'; -- 2.14.3