Tue, Nov 05, 2024 at 10:48:23AM CET, dmantipov@xxxxxxxxx wrote: >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 It is odd to write "I assume" for fix like this. You should know for sure, don't you? >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> >--- >v2: resend after hitting skb refcount underflow once again when looking >around https://syzkaller.appspot.com/bug?extid=0e6ddb1ef80986bdfe64 >--- > net/can/j1939/transport.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > >diff --git a/net/can/j1939/transport.c b/net/can/j1939/transport.c >index 319f47df3330..95f7a7e65a73 100644 >--- a/net/can/j1939/transport.c >+++ b/net/can/j1939/transport.c >@@ -1505,7 +1505,7 @@ 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); >+ skb_queue_tail(&session->skb_queue, skb_get(skb)); > > skcb = j1939_skb_to_cb(skb); > memcpy(&session->skcb, skcb, sizeof(session->skcb)); >-- >2.47.0 > >
