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[Qemu-devel] [PULL 2/7] io/channel-websock: handle continuous reads with
From: |
Daniel P . Berrangé |
Subject: |
[Qemu-devel] [PULL 2/7] io/channel-websock: handle continuous reads without any data |
Date: |
Thu, 15 Feb 2018 17:50:39 +0000 |
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 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 <address@hidden>
Signed-off-by: Daniel P. Berrange <address@hidden>
---
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
- [Qemu-devel] [PULL 0/7] Qio next patches, Daniel P . Berrangé, 2018/02/15
- [Qemu-devel] [PULL 1/7] io: fix QIONetListener memory leak, Daniel P . Berrangé, 2018/02/15
- [Qemu-devel] [PULL 5/7] io: Add /dev/fdset/ support to QIOChannelFile, Daniel P . Berrangé, 2018/02/15
- [Qemu-devel] [PULL 6/7] io/channel-command: Do not kill the child process after closing the pipe, Daniel P . Berrangé, 2018/02/15
- [Qemu-devel] [PULL 2/7] io/channel-websock: handle continuous reads without any data,
Daniel P . Berrangé <=
- [Qemu-devel] [PULL 4/7] io: Don't call close multiple times in QIOChannelFile, Daniel P . Berrangé, 2018/02/15
- [Qemu-devel] [PULL 3/7] io: Fix QIOChannelFile when creating and opening read-write, Daniel P . Berrangé, 2018/02/15
- [Qemu-devel] [PULL 7/7] allow to build with older sed, Daniel P . Berrangé, 2018/02/15
- Re: [Qemu-devel] [PULL 0/7] Qio next patches, Peter Maydell, 2018/02/15
- Re: [Qemu-devel] [PULL 0/7] Qio next patches, Peter Maydell, 2018/02/16