linux-can-fixes-for-6.17-20250910

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Merge tag 'linux-can-fixes-for-6.17-20250910' of git://git.kernel.org/pub/scm/linux/kernel/git/mkl/linux-can

Marc Kleine-Budde says:

====================
pull-request: can 2025-09-10

The 1st patch is by Alex Tran and fixes the Documentation of the
struct bcm_msg_head.

Davide Caratti's patch enabled the VCAN driver as a module for the
Linux self tests.

Tetsuo Handa contributes 3 patches that fix various problems in the
CAN j1939 protocol.

Anssi Hannula's patch fixes a potential use-after-free in the
xilinx_can driver.

Geert Uytterhoeven's patch fixes the rcan_can's suspend to RAM on
R-Car Gen3 using PSCI.

* tag 'linux-can-fixes-for-6.17-20250910' of git://git.kernel.org/pub/scm/linux/kernel/git/mkl/linux-can:
  can: rcar_can: rcar_can_resume(): fix s2ram with PSCI
  can: xilinx_can: xcan_write_frame(): fix use-after-free of transmitted SKB
  can: j1939: j1939_local_ecu_get(): undo increment when j1939_local_ecu_get() fails
  can: j1939: j1939_sk_bind(): call j1939_priv_put() immediately when j1939_local_ecu_get() failed
  can: j1939: implement NETDEV_UNREGISTER notification handler
  selftests: can: enable CONFIG_CAN_VCAN as a module
  docs: networking: can: change bcm_msg_head frames member to support flexible array
====================

Link: https://patch.msgid.link/20250910162907.948454-1-mkl@pengutronix.de
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

Documentation/networking/can.rst

@@ -742,7 +742,7 @@ The broadcast manager sends responses to user space in the same form:
             struct timeval ival1, ival2;    /* count and subsequent interval */
             canid_t can_id;                 /* unique can_id for task */
             __u32 nframes;                  /* number of can_frames following */
-            struct can_frame frames[0];
+            struct can_frame frames[];
     };
 
 The aligned payload 'frames' uses the same basic CAN frame structure defined

drivers/net/can/rcar/rcar_can.c

@@ -861,7 +861,6 @@ static int rcar_can_resume(struct device *dev)
 {
 	struct net_device *ndev = dev_get_drvdata(dev);
 	struct rcar_can_priv *priv = netdev_priv(ndev);
-	u16 ctlr;
 	int err;
 
 	if (!netif_running(ndev))
@@ -873,12 +872,7 @@ static int rcar_can_resume(struct device *dev)
 		return err;
 	}
 
-	ctlr = readw(&priv->regs->ctlr);
+	rcar_can_start(ndev);
-	ctlr &= ~RCAR_CAN_CTLR_SLPM;
-	writew(ctlr, &priv->regs->ctlr);
-	ctlr &= ~RCAR_CAN_CTLR_CANM;
-	writew(ctlr, &priv->regs->ctlr);
-	priv->can.state = CAN_STATE_ERROR_ACTIVE;
 
 	netif_device_attach(ndev);
 	netif_start_queue(ndev);

drivers/net/can/xilinx_can.c

@@ -690,14 +690,6 @@ static void xcan_write_frame(struct net_device *ndev, struct sk_buff *skb,
 		dlc |= XCAN_DLCR_EDL_MASK;
 	}
 
-	if (!(priv->devtype.flags & XCAN_FLAG_TX_MAILBOXES) &&
-	    (priv->devtype.flags & XCAN_FLAG_TXFEMP))
-		can_put_echo_skb(skb, ndev, priv->tx_head % priv->tx_max, 0);
-	else
-		can_put_echo_skb(skb, ndev, 0, 0);
-
-	priv->tx_head++;
-
 	priv->write_reg(priv, XCAN_FRAME_ID_OFFSET(frame_offset), id);
 	/* If the CAN frame is RTR frame this write triggers transmission
 	 * (not on CAN FD)
@@ -730,6 +722,14 @@ static void xcan_write_frame(struct net_device *ndev, struct sk_buff *skb,
 					data[1]);
 		}
 	}
+
+	if (!(priv->devtype.flags & XCAN_FLAG_TX_MAILBOXES) &&
+	    (priv->devtype.flags & XCAN_FLAG_TXFEMP))
+		can_put_echo_skb(skb, ndev, priv->tx_head % priv->tx_max, 0);
+	else
+		can_put_echo_skb(skb, ndev, 0, 0);
+
+	priv->tx_head++;
 }
 
 /**

net/can/j1939/bus.c

@@ -290,8 +290,11 @@ int j1939_local_ecu_get(struct j1939_priv *priv, name_t name, u8 sa)
 	if (!ecu)
 		ecu = j1939_ecu_create_locked(priv, name);
 	err = PTR_ERR_OR_ZERO(ecu);
-	if (err)
+	if (err) {
+		if (j1939_address_is_unicast(sa))
+			priv->ents[sa].nusers--;
 		goto done;
+	}
 
 	ecu->nusers++;
 	/* TODO: do we care if ecu->addr != sa? */

net/can/j1939/j1939-priv.h

@@ -212,6 +212,7 @@ void j1939_priv_get(struct j1939_priv *priv);
 
 /* notify/alert all j1939 sockets bound to ifindex */
 void j1939_sk_netdev_event_netdown(struct j1939_priv *priv);
+void j1939_sk_netdev_event_unregister(struct j1939_priv *priv);
 int j1939_cancel_active_session(struct j1939_priv *priv, struct sock *sk);
 void j1939_tp_init(struct j1939_priv *priv);
 

net/can/j1939/main.c

@@ -377,6 +377,9 @@ static int j1939_netdev_notify(struct notifier_block *nb,
 		j1939_sk_netdev_event_netdown(priv);
 		j1939_ecu_unmap_all(priv);
 		break;
+	case NETDEV_UNREGISTER:
+		j1939_sk_netdev_event_unregister(priv);
+		break;
 	}
 
 	j1939_priv_put(priv);

net/can/j1939/socket.c

@@ -521,6 +521,9 @@ static int j1939_sk_bind(struct socket *sock, struct sockaddr *uaddr, int len)
 	ret = j1939_local_ecu_get(priv, jsk->addr.src_name, jsk->addr.sa);
 	if (ret) {
 		j1939_netdev_stop(priv);
+		jsk->priv = NULL;
+		synchronize_rcu();
+		j1939_priv_put(priv);
 		goto out_release_sock;
 	}
 
@@ -1300,6 +1303,55 @@ void j1939_sk_netdev_event_netdown(struct j1939_priv *priv)
 	read_unlock_bh(&priv->j1939_socks_lock);
 }
 
+void j1939_sk_netdev_event_unregister(struct j1939_priv *priv)
+{
+	struct sock *sk;
+	struct j1939_sock *jsk;
+	bool wait_rcu = false;
+
+rescan: /* The caller is holding a ref on this "priv" via j1939_priv_get_by_ndev(). */
+	read_lock_bh(&priv->j1939_socks_lock);
+	list_for_each_entry(jsk, &priv->j1939_socks, list) {
+		/* Skip if j1939_jsk_add() is not called on this socket. */
+		if (!(jsk->state & J1939_SOCK_BOUND))
+			continue;
+		sk = &jsk->sk;
+		sock_hold(sk);
+		read_unlock_bh(&priv->j1939_socks_lock);
+		/* Check if j1939_jsk_del() is not yet called on this socket after holding
+		 * socket's lock, for both j1939_sk_bind() and j1939_sk_release() call
+		 * j1939_jsk_del() with socket's lock held.
+		 */
+		lock_sock(sk);
+		if (jsk->state & J1939_SOCK_BOUND) {
+			/* Neither j1939_sk_bind() nor j1939_sk_release() called j1939_jsk_del().
+			 * Make this socket no longer bound, by pretending as if j1939_sk_bind()
+			 * dropped old references but did not get new references.
+			 */
+			j1939_jsk_del(priv, jsk);
+			j1939_local_ecu_put(priv, jsk->addr.src_name, jsk->addr.sa);
+			j1939_netdev_stop(priv);
+			/* Call j1939_priv_put() now and prevent j1939_sk_sock_destruct() from
+			 * calling the corresponding j1939_priv_put().
+			 *
+			 * j1939_sk_sock_destruct() is supposed to call j1939_priv_put() after
+			 * an RCU grace period. But since the caller is holding a ref on this
+			 * "priv", we can defer synchronize_rcu() until immediately before
+			 * the caller calls j1939_priv_put().
+			 */
+			j1939_priv_put(priv);
+			jsk->priv = NULL;
+			wait_rcu = true;
+		}
+		release_sock(sk);
+		sock_put(sk);
+		goto rescan;
+	}
+	read_unlock_bh(&priv->j1939_socks_lock);
+	if (wait_rcu)
+		synchronize_rcu();
+}
+
 static int j1939_sk_no_ioctlcmd(struct socket *sock, unsigned int cmd,
 				unsigned long arg)
 {

tools/testing/selftests/net/can/config

@@ -0,0 +1,3 @@
+CONFIG_CAN=m
+CONFIG_CAN_DEV=m
+CONFIG_CAN_VCAN=m