s390/virtio: handle find on invalid queue gracefully

halil-pasic · mstsirkin · commit 3438b2c039b4 · 2019-03-06T11:19:44.000-05:00
A queue with a capacity of zero is clearly not a valid virtio queue.
Some emulators report zero queue size if queried with an invalid queue
index. Instead of crashing in this case let us just return -ENOENT. To
make that work properly, let us fix the notifier cleanup logic as well.

Cc: stable@vger.kernel.org
Signed-off-by: Halil Pasic &lt;pasic@linux.ibm.com&gt;
Signed-off-by: Cornelia Huck &lt;cohuck@redhat.com&gt;
Signed-off-by: Michael S. Tsirkin &lt;mst@redhat.com&gt;
diff --git a/drivers/s390/virtio/virtio_ccw.c b/drivers/s390/virtio/virtio_ccw.c
@@ -272,6 +272,8 @@ static void virtio_ccw_drop_indicators(struct virtio_ccw_device *vcdev)
 {
 	struct virtio_ccw_vq_info *info;
 
+	if (!vcdev->airq_info)
+		return;
 	list_for_each_entry(info, &vcdev->virtqueues, node)
 		drop_airq_indicator(info->vq, vcdev->airq_info);
 }
@@ -413,7 +415,7 @@ static int virtio_ccw_read_vq_conf(struct virtio_ccw_device *vcdev,
 	ret = ccw_io_helper(vcdev, ccw, VIRTIO_CCW_DOING_READ_VQ_CONF);
 	if (ret)
 		return ret;
-	return vcdev->config_block->num;
+	return vcdev->config_block->num ?: -ENOENT;
 }
 
 static void virtio_ccw_del_vq(struct virtqueue *vq, struct ccw1 *ccw)

Original file line number	Diff line number	Diff line change
`@@ -272,6 +272,8 @@ static void virtio_ccw_drop_indicators(struct virtio_ccw_device *vcdev)`
`272`	`272`	`{`
`273`	`273`	`struct virtio_ccw_vq_info *info;`
`274`	`274`
	`275`	`+ if (!vcdev->airq_info)`
	`276`	`+ return;`
`275`	`277`	`list_for_each_entry(info, &vcdev->virtqueues, node)`
`276`	`278`	`drop_airq_indicator(info->vq, vcdev->airq_info);`
`277`	`279`	`}`
`@@ -413,7 +415,7 @@ static int virtio_ccw_read_vq_conf(struct virtio_ccw_device *vcdev,`
`413`	`415`	`ret = ccw_io_helper(vcdev, ccw, VIRTIO_CCW_DOING_READ_VQ_CONF);`
`414`	`416`	`if (ret)`
`415`	`417`	`return ret;`
`416`		`- return vcdev->config_block->num;`
	`418`	`+ return vcdev->config_block->num ?: -ENOENT;`
`417`	`419`	`}`
`418`	`420`
`419`	`421`	`static void virtio_ccw_del_vq(struct virtqueue vq, struct ccw1 ccw)`