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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: DaeRyong Jeong <threeearcat@gmail.com>
Fixes: 6b1e6cc785 ("vhost: new device IOTLB API")
Signed-off-by: Jason Wang <jasowang@redhat.com>
Acked-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Jason Wang 2018-05-22 19:58:57 +08:00 committed by David S. Miller
parent d681bc027a
commit 1b15ad683a
1 changed files with 3 additions and 0 deletions
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3
drivers/vhost/vhost.c
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@ -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,