4.9-stable review patch. If anyone has any objections, please let me know.
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From: Jason Wang jasowang@redhat.com
[ 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@gmail.com Fixes: 6b1e6cc7855b0 ("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 Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- 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,