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Commit 1b15ad68 authored by Jason Wang's avatar Jason Wang Committed by David S. Miller
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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: default avatarDaeRyong Jeong <threeearcat@gmail.com>
Fixes: 6b1e6cc7 ("vhost: new device IOTLB API")
Signed-off-by: default avatarJason Wang <jasowang@redhat.com>
Acked-by: default avatarMichael S. Tsirkin <mst@redhat.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent d681bc02

drivers/vhost/vhost.c

+3 −0
Original line number Diff line number Diff line
@@ -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,