From: Fedor Pchelkin pchelkin@ispras.ru

commit 8c21c54a53ab21842f5050fa090f26b03c0313d6 upstream.

We need to drop skb references taken in j1939_session_skb_queue() when destroying a session in j1939_session_destroy(). Otherwise those skbs would be lost.

Link to Syzkaller info and repro: https://forge.ispras.ru/issues/11743.

Found by Linux Verification Center (linuxtesting.org) with Syzkaller.

V1: https://lore.kernel.org/all/20220708175949.539064-1-pchelkin@ispras.ru

Fixes: 9d71dd0 ("can: add support of SAE J1939 protocol") Suggested-by: Oleksij Rempel o.rempel@pengutronix.de Signed-off-by: Fedor Pchelkin pchelkin@ispras.ru Signed-off-by: Alexey Khoroshilov khoroshilov@ispras.ru Acked-by: Oleksij Rempel o.rempel@pengutronix.de Link: https://lore.kernel.org/all/20220805150216.66313-1-pchelkin@ispras.ru Signed-off-by: Marc Kleine-Budde mkl@pengutronix.de --- net/can/j1939/transport.c | 8 +++++++- 1 file changed, 7 insertions(+), 1 deletion(-)

diff --git a/net/can/j1939/transport.c b/net/can/j1939/transport.c index 9c39b0f5d6e0..2830a12a4dd1 100644 --- a/net/can/j1939/transport.c +++ b/net/can/j1939/transport.c @@ -260,6 +260,8 @@ static void __j1939_session_drop(struct j1939_session *session)

static void j1939_session_destroy(struct j1939_session *session) { + struct sk_buff *skb; + if (session->err) j1939_sk_errqueue(session, J1939_ERRQUEUE_ABORT); else @@ -270,7 +272,11 @@ static void j1939_session_destroy(struct j1939_session *session) WARN_ON_ONCE(!list_empty(&session->sk_session_queue_entry)); WARN_ON_ONCE(!list_empty(&session->active_session_list_entry));

- skb_queue_purge(&session->skb_queue); + while ((skb = skb_dequeue(&session->skb_queue)) != NULL) { + /* drop ref taken in j1939_session_skb_queue() */ + skb_unref(skb); + kfree_skb(skb); + } __j1939_session_drop(session); j1939_priv_put(session->priv); kfree(session);