From: Oleksij Rempel <o.rempel@xxxxxxxxxxxxxx>
This patch delays the j1939_priv_put() until the socket is destroyed via
the sk_destruct callback, to avoid use-after-free problems.
Fixes: 9d71dd0c7009 ("can: add support of SAE J1939 protocol")
Signed-off-by: Oleksij Rempel <o.rempel@xxxxxxxxxxxxxx>
---
net/can/j1939/socket.c | 37 +++++++++++++++++++++++++++++++++++--
1 file changed, 35 insertions(+), 2 deletions(-)
diff --git a/net/can/j1939/socket.c b/net/can/j1939/socket.c
index 4d8ba701e15d..aee94b09ef08 100644
--- a/net/can/j1939/socket.c
+++ b/net/can/j1939/socket.c
@@ -78,7 +78,6 @@ static void j1939_jsk_add(struct j1939_priv *priv, struct j1939_sock *jsk)
{
jsk->state |= J1939_SOCK_BOUND;
j1939_priv_get(priv);
- jsk->priv = priv;
spin_lock_bh(&priv->j1939_socks_lock);
list_add_tail(&jsk->list, &priv->j1939_socks);
@@ -91,7 +90,6 @@ static void j1939_jsk_del(struct j1939_priv *priv, struct j1939_sock *jsk)
list_del_init(&jsk->list);
spin_unlock_bh(&priv->j1939_socks_lock);
- jsk->priv = NULL;
j1939_priv_put(priv);
jsk->state &= ~J1939_SOCK_BOUND;
}
@@ -349,6 +347,34 @@ void j1939_sk_recv(struct j1939_priv *priv, struct sk_buff *skb)
spin_unlock_bh(&priv->j1939_socks_lock);
}
+static void j1939_sk_sock_destruct(struct sock *sk)
+{
+ struct j1939_sock *jsk = j1939_sk(sk);
+
+ /* This function will be call by the generic networking code, when then
+ * the socket is ultimately closed (sk->sk_destruct).
+ *
+ * The race between
+ * - processing a received CAN frame
+ * (can_receive -> j1939_can_recv)
+ * and accessing j1939_priv
+ * ... and ...
+ * - closing a socket
+ * (j1939_can_rx_unregister -> can_rx_unregister)
+ * and calling the final j1939_priv_put()
+ *
+ * is avoided by calling the final j1939_priv_put() from this
+ * RCU deferred cleanup call.
+ */
+ if (jsk->priv) {
+ j1939_priv_put(jsk->priv);
+ jsk->priv = NULL;
+ }
+
+ /* call generic CAN sock destruct */
+ can_sock_destruct(sk);
+}
+
static int j1939_sk_init(struct sock *sk)
{
struct j1939_sock *jsk = j1939_sk(sk);
@@ -371,6 +397,7 @@ static int j1939_sk_init(struct sock *sk)
atomic_set(&jsk->skb_pending, 0);
spin_lock_init(&jsk->sk_session_queue_lock);
INIT_LIST_HEAD(&jsk->sk_session_queue);
+ sk->sk_destruct = j1939_sk_sock_destruct;
return 0;
}
@@ -443,6 +470,12 @@ static int j1939_sk_bind(struct socket *sock, struct sockaddr *uaddr, int len)
}
jsk->ifindex = addr->can_ifindex;
+
+ /* the corresponding j1939_priv_put() is called via
+ * sk->sk_destruct, which points to j1939_sk_sock_destruct()
+ */
+ j1939_priv_get(priv);
+ jsk->priv = priv;
}
/* set default transmit pgn */
--
2.24.0
