4.9-stable review patch. If anyone has any objections, please let me know.
------------------
From: Jason Wang <jasowang@xxxxxxxxxx>
[ Upstream commit 1b15ad683ab42a203f98b67045b40720e99d0e9a ]
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@xxxxxxxxx>
Fixes: 6b1e6cc7855b0 ("vhost: new device IOTLB API")
Signed-off-by: Jason Wang <jasowang@xxxxxxxxxx>
Acked-by: Michael S. Tsirkin <mst@xxxxxxxxxx>
Signed-off-by: David S. Miller <davem@xxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
drivers/vhost/vhost.c | 3 +++
1 file changed, 3 insertions(+)
--- a/drivers/vhost/vhost.c
+++ b/drivers/vhost/vhost.c
@@ -938,6 +938,7 @@ int vhost_process_iotlb_msg(struct vhost
{
int ret = 0;
+ mutex_lock(&dev->mutex);
vhost_dev_lock_vqs(dev);
switch (msg->type) {
case VHOST_IOTLB_UPDATE:
@@ -967,6 +968,8 @@ int vhost_process_iotlb_msg(struct vhost
}
vhost_dev_unlock_vqs(dev);
+ mutex_unlock(&dev->mutex);
+
return ret;
}
ssize_t vhost_chr_write_iter(struct vhost_dev *dev,
