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>

1 files changed, 52 insertions, 0 deletions

diff --git a/net/can/j1939/socket.c b/net/can/j1939/socket.c
index 3d8b588822f9..88e7160d4248 100644
--- a/net/can/j1939/socket.c
+++ b/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)
 {