diff --git a/net/can/j1939/transport.c b/net/can/j1939/transport.c
index 9c8c7c5dc9c3..42fb83605d4c 100644
--- a/net/can/j1939/transport.c
+++ b/net/can/j1939/transport.c
@@ -600,7 +600,10 @@ sk_buff *j1939_tp_tx_dat_new(struct j1939_priv *priv,
 	/* reserve CAN header */
 	skb_reserve(skb, offsetof(struct can_frame, data));
 
-	memcpy(skb->cb, re_skcb, sizeof(skb->cb));
+	/* skb->cb must be large enough to hold a j1939_sk_buff_cb structure */
+	BUILD_BUG_ON(sizeof(skb->cb) < sizeof(*re_skcb));
+
+	memcpy(skb->cb, re_skcb, sizeof(*re_skcb));
 	skcb = j1939_skb_to_cb(skb);
 	if (swap_src_dst)
 		j1939_skbcb_swap(skcb);