>From 88328386f3f652e684ee33dc4cf63dcaed871aea Mon Sep 17 00:00:00 2001 From: Jason Wang Date: Fri, 18 May 2018 17:33:27 +0800 Subject: [PATCH] vhost: synchronize IOTLB message with dev cleanup DaeRyong Jeong reports a race between vhost_dev_cleanup() and vhost_process_iotlb_msg(): Thread interleaving: CPU0 (vhost_process_iotlb_msg) CPU1 (vhost_dev_cleanup) (In the case of both VHOST_IOTLB_UPDATE and VHOST_IOTLB_INVALIDATE) ===== ===== vhost_umem_clean(dev->iotlb); if (!dev->iotlb) { ret = -EFAULT; break; } dev->iotlb = NULL; The reason is we don't synchronize between them, fixing by protecting vhost_process_iotlb_msg() with dev mutex. Reported-by: DaeRyong Jeong Fixes: 6b1e6cc7855b0 ("vhost: new device IOTLB API") Reported-by: DaeRyong Jeong --- drivers/vhost/vhost.c | 3 +++ 1 file changed, 3 insertions(+) diff --git a/drivers/vhost/vhost.c b/drivers/vhost/vhost.c index f3bd8e9..f0be5f3 100644 --- a/drivers/vhost/vhost.c +++ b/drivers/vhost/vhost.c @@ -981,6 +981,7 @@ static int vhost_process_iotlb_msg(struct vhost_dev *dev, { int ret = 0; + mutex_lock(&dev->mutex); vhost_dev_lock_vqs(dev); switch (msg->type) { case VHOST_IOTLB_UPDATE: @@ -1016,6 +1017,8 @@ static int vhost_process_iotlb_msg(struct vhost_dev *dev, } vhost_dev_unlock_vqs(dev); + mutex_unlock(&dev->mutex); + return ret; } ssize_t vhost_chr_write_iter(struct vhost_dev *dev, -- 2.7.4