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Subject[PATCH] can: j1939: fix memory leak of skbs
Date
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.

Fixes: 9d71dd0c7009 ("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>
---
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 307ee1174a6e..d7d86c944d76 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->transmission) {
if (session->err)
j1939_sk_errqueue(session, J1939_ERRQUEUE_TX_ABORT);
@@ -274,7 +276,11 @@ 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);
--
2.25.1
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