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can: j1939: prevent deadlock by changing j1939_socks_lock to rwlock
commit 6cdedc18ba
upstream.
The following 3 locks would race against each other, causing the
deadlock situation in the Syzbot bug report:
- j1939_socks_lock
- active_session_list_lock
- sk_session_queue_lock
A reasonable fix is to change j1939_socks_lock to an rwlock, since in
the rare situations where a write lock is required for the linked list
that j1939_socks_lock is protecting, the code does not attempt to
acquire any more locks. This would break the circular lock dependency,
where, for example, the current thread already locks j1939_socks_lock
and attempts to acquire sk_session_queue_lock, and at the same time,
another thread attempts to acquire j1939_socks_lock while holding
sk_session_queue_lock.
NOTE: This patch along does not fix the unregister_netdevice bug
reported by Syzbot; instead, it solves a deadlock situation to prepare
for one or more further patches to actually fix the Syzbot bug, which
appears to be a reference counting problem within the j1939 codebase.
Reported-by: <syzbot+1591462f226d9cbf0564@syzkaller.appspotmail.com>
Signed-off-by: Ziqi Zhao <astrajoan@yahoo.com>
Reviewed-by: Oleksij Rempel <o.rempel@pengutronix.de>
Acked-by: Oleksij Rempel <o.rempel@pengutronix.de>
Link: https://lore.kernel.org/all/20230721162226.8639-1-astrajoan@yahoo.com
[mkl: remove unrelated newline change]
Cc: stable@vger.kernel.org
Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
parent
8a72a4689a
commit
aedda066d7
3 changed files with 14 additions and 14 deletions
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@ -86,7 +86,7 @@ struct j1939_priv {
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unsigned int tp_max_packet_size;
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/* lock for j1939_socks list */
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spinlock_t j1939_socks_lock;
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rwlock_t j1939_socks_lock;
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struct list_head j1939_socks;
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struct kref rx_kref;
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@ -274,7 +274,7 @@ struct j1939_priv *j1939_netdev_start(struct net_device *ndev)
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return ERR_PTR(-ENOMEM);
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j1939_tp_init(priv);
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spin_lock_init(&priv->j1939_socks_lock);
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rwlock_init(&priv->j1939_socks_lock);
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INIT_LIST_HEAD(&priv->j1939_socks);
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mutex_lock(&j1939_netdev_lock);
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@ -80,16 +80,16 @@ static void j1939_jsk_add(struct j1939_priv *priv, struct j1939_sock *jsk)
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jsk->state |= J1939_SOCK_BOUND;
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j1939_priv_get(priv);
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spin_lock_bh(&priv->j1939_socks_lock);
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write_lock_bh(&priv->j1939_socks_lock);
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list_add_tail(&jsk->list, &priv->j1939_socks);
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spin_unlock_bh(&priv->j1939_socks_lock);
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write_unlock_bh(&priv->j1939_socks_lock);
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}
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static void j1939_jsk_del(struct j1939_priv *priv, struct j1939_sock *jsk)
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{
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spin_lock_bh(&priv->j1939_socks_lock);
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write_lock_bh(&priv->j1939_socks_lock);
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list_del_init(&jsk->list);
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spin_unlock_bh(&priv->j1939_socks_lock);
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write_unlock_bh(&priv->j1939_socks_lock);
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j1939_priv_put(priv);
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jsk->state &= ~J1939_SOCK_BOUND;
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@ -329,13 +329,13 @@ bool j1939_sk_recv_match(struct j1939_priv *priv, struct j1939_sk_buff_cb *skcb)
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struct j1939_sock *jsk;
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bool match = false;
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spin_lock_bh(&priv->j1939_socks_lock);
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read_lock_bh(&priv->j1939_socks_lock);
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list_for_each_entry(jsk, &priv->j1939_socks, list) {
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match = j1939_sk_recv_match_one(jsk, skcb);
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if (match)
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break;
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}
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spin_unlock_bh(&priv->j1939_socks_lock);
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read_unlock_bh(&priv->j1939_socks_lock);
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return match;
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}
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@ -344,11 +344,11 @@ void j1939_sk_recv(struct j1939_priv *priv, struct sk_buff *skb)
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{
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struct j1939_sock *jsk;
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spin_lock_bh(&priv->j1939_socks_lock);
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read_lock_bh(&priv->j1939_socks_lock);
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list_for_each_entry(jsk, &priv->j1939_socks, list) {
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j1939_sk_recv_one(jsk, skb);
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}
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spin_unlock_bh(&priv->j1939_socks_lock);
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read_unlock_bh(&priv->j1939_socks_lock);
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}
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static void j1939_sk_sock_destruct(struct sock *sk)
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@ -1080,12 +1080,12 @@ void j1939_sk_errqueue(struct j1939_session *session,
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}
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/* spread RX notifications to all sockets subscribed to this session */
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spin_lock_bh(&priv->j1939_socks_lock);
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read_lock_bh(&priv->j1939_socks_lock);
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list_for_each_entry(jsk, &priv->j1939_socks, list) {
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if (j1939_sk_recv_match_one(jsk, &session->skcb))
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__j1939_sk_errqueue(session, &jsk->sk, type);
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}
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spin_unlock_bh(&priv->j1939_socks_lock);
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read_unlock_bh(&priv->j1939_socks_lock);
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};
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void j1939_sk_send_loop_abort(struct sock *sk, int err)
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@ -1273,7 +1273,7 @@ void j1939_sk_netdev_event_netdown(struct j1939_priv *priv)
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struct j1939_sock *jsk;
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int error_code = ENETDOWN;
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spin_lock_bh(&priv->j1939_socks_lock);
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read_lock_bh(&priv->j1939_socks_lock);
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list_for_each_entry(jsk, &priv->j1939_socks, list) {
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jsk->sk.sk_err = error_code;
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if (!sock_flag(&jsk->sk, SOCK_DEAD))
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@ -1281,7 +1281,7 @@ void j1939_sk_netdev_event_netdown(struct j1939_priv *priv)
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j1939_sk_queue_drop_all(priv, jsk, error_code);
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}
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spin_unlock_bh(&priv->j1939_socks_lock);
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read_unlock_bh(&priv->j1939_socks_lock);
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}
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static int j1939_sk_no_ioctlcmd(struct socket *sock, unsigned int cmd,
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