From: Eryu Guan Date: Mon, 27 Jan 2020 19:02:25 +0000 Subject: [PATCH] virtiofsd: stop all queue threads on exit in virtio_loop() 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 Signed-off-by: Eryu Guan Reviewed-by: Stefan Hajnoczi Signed-off-by: Dr. David Alan Gilbert (cherry picked from commit 9883df8ccae6d744a0c8d9cbf9d62b1797d70ebd) --- tools/virtiofsd/fuse_virtio.c | 13 +++++++++++++ 1 file changed, 13 insertions(+) diff --git a/tools/virtiofsd/fuse_virtio.c b/tools/virtiofsd/fuse_virtio.c index 9f6582343c..80a6e929df 100644 --- a/tools/virtiofsd/fuse_virtio.c +++ b/tools/virtiofsd/fuse_virtio.c @@ -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;