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virtiofsd: stop all queue threads on exit in virtio_loop()

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On guest graceful shutdown, virtiofsd receives VHOST_USER_GET_VRING_BASE
request from VMM and shuts down virtqueues by calling fv_set_started(),
which joins fv_queue_thread() threads. So when virtio_loop() returns,
there should be no thread is still accessing data in fuse session and/or
virtio dev.

But on abnormal exit, e.g. guest got killed for whatever reason,
vhost-user socket is closed and virtio_loop() breaks out the main loop
and returns to main(). But it's possible fv_queue_worker()s are still
working and accessing fuse session and virtio dev, which results in
crash or use-after-free.

Fix it by stopping fv_queue_thread()s before virtio_loop() returns,
to make sure there's no-one could access fuse session and virtio dev.

Reported-by: Qingming Su <qingming.su@linux.alibaba.com>
Signed-off-by: Eryu Guan <eguan@linux.alibaba.com>
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
This commit is contained in:
Eryu Guan 2020-01-07 12:15:21 +08:00 committed by Dr. David Alan Gilbert
parent a931b6861e
commit 9883df8cca
1 changed files with 13 additions and 0 deletions
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13
tools/virtiofsd/fuse_virtio.c
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@ -815,6 +815,19 @@ int virtio_loop(struct fuse_session *se)
}
}
/*
* Make sure all fv_queue_thread()s quit on exit, as we're about to
* free virtio dev and fuse session, no one should access them anymore.
*/
for (int i = 0; i < se->virtio_dev->nqueues; i++) {
if (!se->virtio_dev->qi[i]) {
continue;
}
fuse_log(FUSE_LOG_INFO, "%s: Stopping queue %d thread\n", __func__, i);
fv_queue_cleanup_thread(se->virtio_dev, i);
}
fuse_log(FUSE_LOG_INFO, "%s: Exit\n", __func__);
return 0;