diff --git a/sys/dev/netif/iwi/if_iwi.c b/sys/dev/netif/iwi/if_iwi.c
--- a/sys/dev/netif/iwi/if_iwi.c
+++ b/sys/dev/netif/iwi/if_iwi.c
@@ -1801,7 +1801,7 @@
 	desc->hdr.flags = IWI_HDR_FLAG_IRQ;
 	desc->type = type;
 	desc->len = len;
-	memcpy(desc->data, data, len);
+	memcpy(desc->data, data, MIN(len, sizeof(desc->data)));
 
 	bus_dmamap_sync(sc->cmdq.desc_dmat, sc->cmdq.desc_map,
 	    BUS_DMASYNC_PREWRITE);