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can: j1939: move j1939_priv_put() into sk_destruct callback 

This patch delays the j1939_priv_put() until the socket is destroyed via
the sk_destruct callback, to avoid use-after-free problems.

Fixes: 9d71dd0c70 ("can: add support of SAE J1939 protocol")
Signed-off-by: Oleksij Rempel <o.rempel@pengutronix.de>
This commit is contained in:
Oleksij Rempel 2019-11-07 11:57:36 +01:00 committed by Marc Kleine-Budde
parent 975987e701
commit 25fe97cb76
1 changed files with 35 additions and 2 deletions
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37
net/can/j1939/socket.c
View File

@ -78,7 +78,6 @@ static void j1939_jsk_add(struct j1939_priv *priv, struct j1939_sock *jsk)
{ {
jsk->state |= J1939_SOCK_BOUND; jsk->state |= J1939_SOCK_BOUND;
j1939_priv_get(priv); j1939_priv_get(priv);
jsk->priv = priv;
spin_lock_bh(&priv->j1939_socks_lock); spin_lock_bh(&priv->j1939_socks_lock);
list_add_tail(&jsk->list, &priv->j1939_socks); 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); list_del_init(&jsk->list);
spin_unlock_bh(&priv->j1939_socks_lock); spin_unlock_bh(&priv->j1939_socks_lock);
jsk->priv = NULL;
j1939_priv_put(priv); j1939_priv_put(priv);
jsk->state &= ~J1939_SOCK_BOUND; 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); 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) static int j1939_sk_init(struct sock *sk)
{ {
struct j1939_sock *jsk = j1939_sk(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); atomic_set(&jsk->skb_pending, 0);
spin_lock_init(&jsk->sk_session_queue_lock); spin_lock_init(&jsk->sk_session_queue_lock);
INIT_LIST_HEAD(&jsk->sk_session_queue); INIT_LIST_HEAD(&jsk->sk_session_queue);
sk->sk_destruct = j1939_sk_sock_destruct;
return 0; return 0;
} }
@ -443,6 +470,12 @@ static int j1939_sk_bind(struct socket *sock, struct sockaddr *uaddr, int len)
} }
jsk->ifindex = addr->can_ifindex; 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 */ /* set default transmit pgn */