On Thu, Dec 28, 2017 at 12:36:18PM +0300, Denis V. Lunev wrote:
From: Edgar Kaziakhmedov <address@hidden>
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 tcp socket. But this subroutine
doesn't cover scenario when socket was closed while handshaking. Therefore,
if G_IO_IN is caught and qio_channel_websock_handshake_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:
- 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 usage
Signed-off-by: Edgar Kaziakhmedov <address@hidden>
Signed-off-by: Denis V. Lunev <address@hidden>
CC: Daniel P. Berrange <address@hidden>
---
io/channel-websock.c | 8 +++++---
1 file changed, 5 insertions(+), 3 deletions(-)
diff --git a/io/channel-websock.c b/io/channel-websock.c
index 87ebdeb..71f046a 100644
--- a/io/channel-websock.c
+++ b/io/channel-websock.c
@@ -581,9 +581,11 @@ static gboolean
qio_channel_websock_handshake_io(QIOChannel *ioc,
return FALSE;
}
if (ret == 0) {
- trace_qio_channel_websock_handshake_pending(ioc, G_IO_IN);
- /* need more data still */
- return TRUE;
+ /* If G_IN_IO happened and there is no data to read, close connection
*/
+ error_setg(&err, "connection was closed");
+ qio_task_set_error(task, err);
+ qio_task_complete(task);
+ return FALSE;
This is bogus - 'ret == 0' from qio_channel_websock_handshake_read()
does *not* imply end of file.
It says we have read some data, but not yet seen the end of the HTTP
headers.