Since 'j1939_session_skb_queue()' do an extra 'skb_get()' for each new skb, I assume that the same should be done for an initial one in 'j1939_session_new()' just to avoid refcount underflow. Reported-by: syzbot+d4e8dc385d9258220c31@xxxxxxxxxxxxxxxxxxxxxxxxx Closes: https://syzkaller.appspot.com/bug?extid=d4e8dc385d9258220c31 Fixes: 9d71dd0c7009 ("can: add support of SAE J1939 protocol") Signed-off-by: Dmitry Antipov <dmantipov@xxxxxxxxx> --- net/can/j1939/transport.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) diff --git a/net/can/j1939/transport.c b/net/can/j1939/transport.c index 319f47df3330..fecee36dbb70 100644 --- a/net/can/j1939/transport.c +++ b/net/can/j1939/transport.c @@ -1505,7 +1505,8 @@ static struct j1939_session *j1939_session_new(struct j1939_priv *priv, session->state = J1939_SESSION_NEW; skb_queue_head_init(&session->skb_queue); - skb_queue_tail(&session->skb_queue, skb); + /* Take an extra ref just like in j1939_session_skb_queue(). */ + skb_queue_tail(&session->skb_queue, skb_get(skb)); skcb = j1939_skb_to_cb(skb); memcpy(&session->skcb, skcb, sizeof(session->skcb)); -- 2.46.2
