Merge patch series "can: j1939: resend lost patches for buffer init and netdevice tracking"

Oleksij Rempel <o.rempel@pengutronix.de> says:

This series collects and resends two j1939 patches that were previously
lost on their way upstream. They address different, unconnected issues in
the stack:

- Patch 1 prevents residual data leaks by zeroing the allocated receive
  buffer in j1939_session_fresh_new().
- Patch 2 implements netdevice_tracker for j1939_{priv,session,ecu}
  management to help investigate a dev_hold()/dev_put() refcount
  leak (unregister_netdevice() waiting for vcan0) reported by syzbot.

Link: https://patch.msgid.link/20260728055835.1151785-1-o.rempel@pengutronix.de
Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>

4 files changed, 12 insertions, 5 deletions

diff --git a/net/can/j1939/bus.c b/net/can/j1939/bus.c
index dc374286eeb6..cdc3c0a71937 100644
--- a/net/can/j1939/bus.c
+++ b/net/can/j1939/bus.c
@@ -20,6 +20,7 @@ static void __j1939_ecu_release(struct kref *kref)
 	struct j1939_priv *priv = ecu->priv;
 
 	list_del(&ecu->list);
+	netdev_put(priv->ndev, &ecu->priv_dev_tracker);
 	kfree(ecu);
 	j1939_priv_put(priv);
 }
@@ -155,6 +156,7 @@ struct j1939_ecu *j1939_ecu_create_locked(struct j1939_priv *priv, name_t name)
 	if (!ecu)
 		return ERR_PTR(-ENOMEM);
 	kref_init(&ecu->kref);
+	netdev_hold(priv->ndev, &ecu->priv_dev_tracker, gfp_any());
 	ecu->addr = J1939_IDLE_ADDR;
 	ecu->name = name;
 
diff --git a/net/can/j1939/j1939-priv.h b/net/can/j1939/j1939-priv.h
index 81f58924b4ac..cf26352d1d8c 100644
--- a/net/can/j1939/j1939-priv.h
+++ b/net/can/j1939/j1939-priv.h
@@ -38,6 +38,7 @@ struct j1939_ecu {
 	struct hrtimer ac_timer;
 	struct kref kref;
 	struct j1939_priv *priv;
+	netdevice_tracker priv_dev_tracker;
 
 	/* count users, to help transport protocol decide for interaction */
 	int nusers;
@@ -60,6 +61,7 @@ struct j1939_priv {
 	rwlock_t lock;
 
 	struct net_device *ndev;
+	netdevice_tracker dev_tracker;
 
 	/* list of 256 ecu ptrs, that cache the claimed addresses.
 	 * also protected by the above lock
@@ -230,6 +232,7 @@ enum j1939_session_state {
 
 struct j1939_session {
 	struct j1939_priv *priv;
+	netdevice_tracker priv_dev_tracker;
 	struct list_head active_session_list_entry;
 	struct list_head sk_session_queue_entry;
 	struct kref kref;
diff --git a/net/can/j1939/main.c b/net/can/j1939/main.c
index 9937c04241bc..5e5e6c228f22 100644
--- a/net/can/j1939/main.c
+++ b/net/can/j1939/main.c
@@ -137,7 +137,7 @@ static struct j1939_priv *j1939_priv_create(struct net_device *ndev)
 	priv->ndev = ndev;
 	kref_init(&priv->kref);
 	kref_init(&priv->rx_kref);
-	dev_hold(ndev);
+	netdev_hold(ndev, &priv->dev_tracker, GFP_KERNEL);
 
 	netdev_dbg(priv->ndev, "%s : 0x%p\n", __func__, priv);
 
@@ -163,7 +163,7 @@ static void __j1939_priv_release(struct kref *kref)
 	WARN_ON_ONCE(!list_empty(&priv->ecus));
 	WARN_ON_ONCE(!list_empty(&priv->j1939_socks));
 
-	dev_put(ndev);
+	netdev_put(ndev, &priv->dev_tracker);
 	kfree(priv);
 }
 
@@ -281,7 +281,7 @@ struct j1939_priv *j1939_netdev_start(struct net_device *ndev)
 		 */
 		kref_get(&priv_new->rx_kref);
 		mutex_unlock(&j1939_netdev_lock);
-		dev_put(ndev);
+		netdev_put(ndev, &priv->dev_tracker);
 		kfree(priv);
 		return priv_new;
 	}
@@ -298,7 +298,7 @@ struct j1939_priv *j1939_netdev_start(struct net_device *ndev)
 	j1939_priv_set(ndev, NULL);
 	mutex_unlock(&j1939_netdev_lock);
 
-	dev_put(ndev);
+	netdev_put(ndev, &priv->dev_tracker);
 	kfree(priv);
 
 	return ERR_PTR(ret);
diff --git a/net/can/j1939/transport.c b/net/can/j1939/transport.c
index 8a31cb23bc76..8fcfd13e5e6f 100644
--- a/net/can/j1939/transport.c
+++ b/net/can/j1939/transport.c
@@ -283,6 +283,7 @@ static void j1939_session_destroy(struct j1939_session *session)
 		kfree_skb(skb);
 	}
 	__j1939_session_drop(session);
+	netdev_put(session->priv->ndev, &session->priv_dev_tracker);
 	j1939_priv_put(session->priv);
 	kfree(session);
 }
@@ -1526,6 +1527,7 @@ static struct j1939_session *j1939_session_new(struct j1939_priv *priv,
 	INIT_LIST_HEAD(&session->active_session_list_entry);
 	INIT_LIST_HEAD(&session->sk_session_queue_entry);
 	kref_init(&session->kref);
+	netdev_hold(priv->ndev, &session->priv_dev_tracker, gfp_any());
 
 	j1939_priv_get(priv);
 	session->priv = priv;
@@ -1579,7 +1581,7 @@ j1939_session *j1939_session_fresh_new(struct j1939_priv *priv,
 	}
 
 	/* alloc data area */
-	skb_put(skb, size);
+	skb_put_zero(skb, size);
 	/* skb is recounted in j1939_session_new() */
 	return session;
 }