From f79ea4755f6bac95b8df24ca9a7df1707e72aa27 Mon Sep 17 00:00:00 2001 From: Oleksij Rempel Date: Thu, 17 Jun 2021 15:06:23 +0200 Subject: [PATCH] can: j1939: j1939_sk_init(): set SOCK_RCU_FREE to call sk_destruct() after RCU is done commit 22c696fed25c63c7f67508309820358b94a96b6d upstream. Set SOCK_RCU_FREE to let RCU to call sk_destruct() on completion. Without this patch, we will run in to j1939_can_recv() after priv was freed by j1939_sk_release()->j1939_sk_sock_destruct() Fixes: 25fe97cb7620 ("can: j1939: move j1939_priv_put() into sk_destruct callback") Link: https://lore.kernel.org/r/20210617130623.12705-1-o.rempel@pengutronix.de Cc: linux-stable Reported-by: Thadeu Lima de Souza Cascardo Reported-by: syzbot+bdf710cfc41c186fdff3@syzkaller.appspotmail.com Signed-off-by: Oleksij Rempel Signed-off-by: Marc Kleine-Budde Signed-off-by: Greg Kroah-Hartman --- net/can/j1939/main.c | 4 ++++ net/can/j1939/socket.c | 3 +++ 2 files changed, 7 insertions(+) diff --git a/net/can/j1939/main.c b/net/can/j1939/main.c index e52330f..6884d18 100644 --- a/net/can/j1939/main.c +++ b/net/can/j1939/main.c @@ -193,6 +193,10 @@ static void j1939_can_rx_unregister(struct j1939_priv *priv) can_rx_unregister(dev_net(ndev), ndev, J1939_CAN_ID, J1939_CAN_MASK, j1939_can_recv, priv); + /* The last reference of priv is dropped by the RCU deferred + * j1939_sk_sock_destruct() of the last socket, so we can + * safely drop this reference here. + */ j1939_priv_put(priv); } diff --git a/net/can/j1939/socket.c b/net/can/j1939/socket.c index 56aa661..fce8bc8 100644 --- a/net/can/j1939/socket.c +++ b/net/can/j1939/socket.c @@ -398,6 +398,9 @@ 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); + + /* j1939_sk_sock_destruct() depends on SOCK_RCU_FREE flag */ + sock_set_flag(sk, SOCK_RCU_FREE); sk->sk_destruct = j1939_sk_sock_destruct; sk->sk_protocol = CAN_J1939; -- 2.7.4