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When DPO >= session->pkt.total, the subsequent j1939_session_skb_get() returns NULL, and j1939_session_completed() passes it to j1939_sk_recv() which dereferences oskb->sk, causing a kernel panic. Oops: general protection fault, 0000 [#1] SMP KASAN NOPTI KASAN: null-ptr-deref in range [0x0000000000000018-0x000000000000001f] RIP: 0010:j1939_sk_recv (socket.c:318 socket.c:363) Call Trace: j1939_xtp_rx_eoma (transport.c:1235 transport.c:1412) j1939_tp_recv (transport.c:2141 transport.c:2189) j1939_can_recv (main.c:108) Validate DPO against session->pkt.total in j1939_xtp_rx_dpo_one() and abort the session if out of bounds. Also add a NULL guard in j1939_session_completed() as defense in depth. Fixes: 9d71dd0c7009 ("can: add support of SAE J1939 protocol") Reported-by: Xiang Mei Signed-off-by: Weiming Shi --- net/can/j1939/transport.c | 13 ++++++++++--- 1 file changed, 10 insertions(+), 3 deletions(-) diff --git a/net/can/j1939/transport.c b/net/can/j1939/transport.c index df93d57907da..9b0d67c8a9a0 100644 --- a/net/can/j1939/transport.c +++ b/net/can/j1939/transport.c @@ -1231,9 +1231,11 @@ static void j1939_session_completed(struct j1939_session *session) if (!session->transmission) { se_skb = j1939_session_skb_get(session); - /* distribute among j1939 receivers */ - j1939_sk_recv(session->priv, se_skb); - consume_skb(se_skb); + if (se_skb) { + /* distribute among j1939 receivers */ + j1939_sk_recv(session->priv, se_skb); + consume_skb(se_skb); + } } j1939_session_deactivate_activate_next(session); @@ -1818,6 +1820,11 @@ static void j1939_xtp_rx_dpo_one(struct j1939_session *session, /* transmitted without problems */ session->pkt.dpo = j1939_etp_ctl_to_packet(skb->data); + if (session->pkt.dpo >= session->pkt.total) { + j1939_session_timers_cancel(session); + j1939_session_cancel(session, J1939_XTP_ABORT_FAULT); + return; + } session->last_cmd = dat[0]; j1939_tp_set_rxtimeout(session, 750); -- 2.43.0