Merge tag 'for_linus' of git://git.kernel.org/pub/scm/linux/kernel/git/mst/vhost

Pull vhost/virtio fixes from Michael Tsirkin:
 "A couple of last-minute fixes"

* tag 'for_linus' of git://git.kernel.org/pub/scm/linux/kernel/git/mst/vhost:
  vhost/vsock: fix use-after-free in network stack callers
  virtio/s390: fix race in ccw_io_helper()
  virtio/s390: avoid race on vcdev->config
  vhost/vsock: fix reset orphans race with close timeout

2 files changed, 62 insertions, 34 deletions

diff --git a/drivers/s390/virtio/virtio_ccw.c b/drivers/s390/virtio/virtio_ccw.c
index 97b6f197f007..c9c57b4a0b71 100644
--- a/drivers/s390/virtio/virtio_ccw.c
+++ b/drivers/s390/virtio/virtio_ccw.c
@@ -56,6 +56,7 @@ struct virtio_ccw_device {
 	unsigned int revision; /* Transport revision */
 	wait_queue_head_t wait_q;
 	spinlock_t lock;
+	struct mutex io_lock; /* Serializes I/O requests */
 	struct list_head virtqueues;
 	unsigned long indicators;
 	unsigned long indicators2;
@@ -296,6 +297,7 @@ static int ccw_io_helper(struct virtio_ccw_device *vcdev,
 	unsigned long flags;
 	int flag = intparm & VIRTIO_CCW_INTPARM_MASK;
 
+	mutex_lock(&vcdev->io_lock);
 	do {
 		spin_lock_irqsave(get_ccwdev_lock(vcdev->cdev), flags);
 		ret = ccw_device_start(vcdev->cdev, ccw, intparm, 0, 0);
@@ -308,7 +310,9 @@ static int ccw_io_helper(struct virtio_ccw_device *vcdev,
 		cpu_relax();
 	} while (ret == -EBUSY);
 	wait_event(vcdev->wait_q, doing_io(vcdev, flag) == 0);
-	return ret ? ret : vcdev->err;
+	ret = ret ? ret : vcdev->err;
+	mutex_unlock(&vcdev->io_lock);
+	return ret;
 }
 
 static void virtio_ccw_drop_indicator(struct virtio_ccw_device *vcdev,
@@ -828,6 +832,7 @@ static void virtio_ccw_get_config(struct virtio_device *vdev,
 	int ret;
 	struct ccw1 *ccw;
 	void *config_area;
+	unsigned long flags;
 
 	ccw = kzalloc(sizeof(*ccw), GFP_DMA | GFP_KERNEL);
 	if (!ccw)
@@ -846,11 +851,13 @@ static void virtio_ccw_get_config(struct virtio_device *vdev,
 	if (ret)
 		goto out_free;
 
+	spin_lock_irqsave(&vcdev->lock, flags);
 	memcpy(vcdev->config, config_area, offset + len);
-	if (buf)
-		memcpy(buf, &vcdev->config[offset], len);
 	if (vcdev->config_ready < offset + len)
 		vcdev->config_ready = offset + len;
+	spin_unlock_irqrestore(&vcdev->lock, flags);
+	if (buf)
+		memcpy(buf, config_area + offset, len);
 
 out_free:
 	kfree(config_area);
@@ -864,6 +871,7 @@ static void virtio_ccw_set_config(struct virtio_device *vdev,
 	struct virtio_ccw_device *vcdev = to_vc_device(vdev);
 	struct ccw1 *ccw;
 	void *config_area;
+	unsigned long flags;
 
 	ccw = kzalloc(sizeof(*ccw), GFP_DMA | GFP_KERNEL);
 	if (!ccw)
@@ -876,9 +884,11 @@ static void virtio_ccw_set_config(struct virtio_device *vdev,
 	/* Make sure we don't overwrite fields. */
 	if (vcdev->config_ready < offset)
 		virtio_ccw_get_config(vdev, 0, NULL, offset);
+	spin_lock_irqsave(&vcdev->lock, flags);
 	memcpy(&vcdev->config[offset], buf, len);
 	/* Write the config area to the host. */
 	memcpy(config_area, vcdev->config, sizeof(vcdev->config));
+	spin_unlock_irqrestore(&vcdev->lock, flags);
 	ccw->cmd_code = CCW_CMD_WRITE_CONF;
 	ccw->flags = 0;
 	ccw->count = offset + len;
@@ -1247,6 +1257,7 @@ static int virtio_ccw_online(struct ccw_device *cdev)
 	init_waitqueue_head(&vcdev->wait_q);
 	INIT_LIST_HEAD(&vcdev->virtqueues);
 	spin_lock_init(&vcdev->lock);
+	mutex_init(&vcdev->io_lock);
 
 	spin_lock_irqsave(get_ccwdev_lock(cdev), flags);
 	dev_set_drvdata(&cdev->dev, vcdev);
diff --git a/drivers/vhost/vsock.c b/drivers/vhost/vsock.c
index 34bc3ab40c6d..98ed5be132c6 100644
--- a/drivers/vhost/vsock.c
+++ b/drivers/vhost/vsock.c
@@ -15,6 +15,7 @@
 #include <net/sock.h>
 #include <linux/virtio_vsock.h>
 #include <linux/vhost.h>
+#include <linux/hashtable.h>
 
 #include <net/af_vsock.h>
 #include "vhost.h"
@@ -27,14 +28,14 @@ enum {
 
 /* Used to track all the vhost_vsock instances on the system. */
 static DEFINE_SPINLOCK(vhost_vsock_lock);
-static LIST_HEAD(vhost_vsock_list);
+static DEFINE_READ_MOSTLY_HASHTABLE(vhost_vsock_hash, 8);
 
 struct vhost_vsock {
 	struct vhost_dev dev;
 	struct vhost_virtqueue vqs[2];
 
-	/* Link to global vhost_vsock_list, protected by vhost_vsock_lock */
-	struct list_head list;
+	/* Link to global vhost_vsock_hash, writes use vhost_vsock_lock */
+	struct hlist_node hash;
 
 	struct vhost_work send_pkt_work;
 	spinlock_t send_pkt_list_lock;
@@ -50,11 +51,14 @@ static u32 vhost_transport_get_local_cid(void)
 	return VHOST_VSOCK_DEFAULT_HOST_CID;
 }
 
-static struct vhost_vsock *__vhost_vsock_get(u32 guest_cid)
+/* Callers that dereference the return value must hold vhost_vsock_lock or the
+ * RCU read lock.
+ */
+static struct vhost_vsock *vhost_vsock_get(u32 guest_cid)
 {
 	struct vhost_vsock *vsock;
 
-	list_for_each_entry(vsock, &vhost_vsock_list, list) {
+	hash_for_each_possible_rcu(vhost_vsock_hash, vsock, hash, guest_cid) {
 		u32 other_cid = vsock->guest_cid;
 
 		/* Skip instances that have no CID yet */
@@ -69,17 +73,6 @@ static struct vhost_vsock *__vhost_vsock_get(u32 guest_cid)
 	return NULL;
 }
 
-static struct vhost_vsock *vhost_vsock_get(u32 guest_cid)
-{
-	struct vhost_vsock *vsock;
-
-	spin_lock_bh(&vhost_vsock_lock);
-	vsock = __vhost_vsock_get(guest_cid);
-	spin_unlock_bh(&vhost_vsock_lock);
-
-	return vsock;
-}
-
 static void
 vhost_transport_do_send_pkt(struct vhost_vsock *vsock,
 			    struct vhost_virtqueue *vq)
@@ -210,9 +203,12 @@ vhost_transport_send_pkt(struct virtio_vsock_pkt *pkt)
 	struct vhost_vsock *vsock;
 	int len = pkt->len;
 
+	rcu_read_lock();
+
 	/* Find the vhost_vsock according to guest context id  */
 	vsock = vhost_vsock_get(le64_to_cpu(pkt->hdr.dst_cid));
 	if (!vsock) {
+		rcu_read_unlock();
 		virtio_transport_free_pkt(pkt);
 		return -ENODEV;
 	}
@@ -225,6 +221,8 @@ vhost_transport_send_pkt(struct virtio_vsock_pkt *pkt)
 	spin_unlock_bh(&vsock->send_pkt_list_lock);
 
 	vhost_work_queue(&vsock->dev, &vsock->send_pkt_work);
+
+	rcu_read_unlock();
 	return len;
 }
 
@@ -234,12 +232,15 @@ vhost_transport_cancel_pkt(struct vsock_sock *vsk)
 	struct vhost_vsock *vsock;
 	struct virtio_vsock_pkt *pkt, *n;
 	int cnt = 0;
+	int ret = -ENODEV;
 	LIST_HEAD(freeme);
 
+	rcu_read_lock();
+
 	/* Find the vhost_vsock according to guest context id  */
 	vsock = vhost_vsock_get(vsk->remote_addr.svm_cid);
 	if (!vsock)
-		return -ENODEV;
+		goto out;
 
 	spin_lock_bh(&vsock->send_pkt_list_lock);
 	list_for_each_entry_safe(pkt, n, &vsock->send_pkt_list, list) {
@@ -265,7 +266,10 @@ vhost_transport_cancel_pkt(struct vsock_sock *vsk)
 			vhost_poll_queue(&tx_vq->poll);
 	}
 
-	return 0;
+	ret = 0;
+out:
+	rcu_read_unlock();
+	return ret;
 }
 
 static struct virtio_vsock_pkt *
@@ -533,10 +537,6 @@ static int vhost_vsock_dev_open(struct inode *inode, struct file *file)
 	spin_lock_init(&vsock->send_pkt_list_lock);
 	INIT_LIST_HEAD(&vsock->send_pkt_list);
 	vhost_work_init(&vsock->send_pkt_work, vhost_transport_send_pkt_work);
-
-	spin_lock_bh(&vhost_vsock_lock);
-	list_add_tail(&vsock->list, &vhost_vsock_list);
-	spin_unlock_bh(&vhost_vsock_lock);
 	return 0;
 
 out:
@@ -563,13 +563,21 @@ static void vhost_vsock_reset_orphans(struct sock *sk)
 	 * executing.
 	 */
 
-	if (!vhost_vsock_get(vsk->remote_addr.svm_cid)) {
-		sock_set_flag(sk, SOCK_DONE);
-		vsk->peer_shutdown = SHUTDOWN_MASK;
-		sk->sk_state = SS_UNCONNECTED;
-		sk->sk_err = ECONNRESET;
-		sk->sk_error_report(sk);
-	}
+	/* If the peer is still valid, no need to reset connection */
+	if (vhost_vsock_get(vsk->remote_addr.svm_cid))
+		return;
+
+	/* If the close timeout is pending, let it expire.  This avoids races
+	 * with the timeout callback.
+	 */
+	if (vsk->close_work_scheduled)
+		return;
+
+	sock_set_flag(sk, SOCK_DONE);
+	vsk->peer_shutdown = SHUTDOWN_MASK;
+	sk->sk_state = SS_UNCONNECTED;
+	sk->sk_err = ECONNRESET;
+	sk->sk_error_report(sk);
 }
 
 static int vhost_vsock_dev_release(struct inode *inode, struct file *file)
@@ -577,9 +585,13 @@ static int vhost_vsock_dev_release(struct inode *inode, struct file *file)
 	struct vhost_vsock *vsock = file->private_data;
 
 	spin_lock_bh(&vhost_vsock_lock);
-	list_del(&vsock->list);
+	if (vsock->guest_cid)
+		hash_del_rcu(&vsock->hash);
 	spin_unlock_bh(&vhost_vsock_lock);
 
+	/* Wait for other CPUs to finish using vsock */
+	synchronize_rcu();
+
 	/* Iterating over all connections for all CIDs to find orphans is
 	 * inefficient.  Room for improvement here. */
 	vsock_for_each_connected_socket(vhost_vsock_reset_orphans);
@@ -620,12 +632,17 @@ static int vhost_vsock_set_cid(struct vhost_vsock *vsock, u64 guest_cid)
 
 	/* Refuse if CID is already in use */
 	spin_lock_bh(&vhost_vsock_lock);
-	other = __vhost_vsock_get(guest_cid);
+	other = vhost_vsock_get(guest_cid);
 	if (other && other != vsock) {
 		spin_unlock_bh(&vhost_vsock_lock);
 		return -EADDRINUSE;
 	}
+
+	if (vsock->guest_cid)
+		hash_del_rcu(&vsock->hash);
+
 	vsock->guest_cid = guest_cid;
+	hash_add_rcu(vhost_vsock_hash, &vsock->hash, guest_cid);
 	spin_unlock_bh(&vhost_vsock_lock);
 
 	return 0;