From: Oliver Hartkopp socketcan@hartkopp.net

The read access to struct canxl_frame::len inside of a j1939 created skbuff revealed a missing initialization of reserved and later filled elements in struct can_frame.

This patch initializes the 8 byte CAN header with zero.

Fixes: 9d71dd0c7009 ("can: add support of SAE J1939 protocol") Cc: Oleksij Rempel o.rempel@pengutronix.de Link: https://lore.kernel.org/linux-can/20221104052235.GA6474@pengutronix.de Reported-by: syzbot+d168ec0caca4697e03b1@syzkaller.appspotmail.com Signed-off-by: Oliver Hartkopp socketcan@hartkopp.net Link: https://lore.kernel.org/all/20221104075000.105414-1-socketcan@hartkopp.net Cc: stable@vger.kernel.org Signed-off-by: Marc Kleine-Budde mkl@pengutronix.de --- net/can/j1939/main.c | 3 +++ 1 file changed, 3 insertions(+)

diff --git a/net/can/j1939/main.c b/net/can/j1939/main.c index 144c86b0e3ff..821d4ff303b3 100644 --- a/net/can/j1939/main.c +++ b/net/can/j1939/main.c @@ -336,6 +336,9 @@ int j1939_send_one(struct j1939_priv *priv, struct sk_buff *skb) /* re-claim the CAN_HDR from the SKB */ cf = skb_push(skb, J1939_CAN_HDR);

+ /* initialize header structure */ + memset(cf, 0, J1939_CAN_HDR); + /* make it a full can frame again */ skb_put(skb, J1939_CAN_FTR + (8 - dlc));