wpa_supplicant uses PF_ROUTE to return the routing table in order to

determine the length of the routing table buffer. As of 81728a538d
wpa_supplicant is started before the routing table has been populated
resulting in the length of zero to be returned. This causes
wpa_supplicant to loop endlessly. (The workaround is to kill and restart
wpa_supplicant as by the time it is restarted the routing table is
populated.)

(Personally, I was not able to reproduce this unless wlan0 was a member of
lagg0. However, others experienced this problem on standalone wlan0.)

PR:		252844
Submitted by:	shu <ankohuu _ outlook.com>
Reported by:	shu <ankohuu _ outlook.com>
Reviewed by:	cy
X-MFC with:	81728a538d
Differential Revision:	https://reviews.freebsd.org/D28249

contrib/wpa/src/drivers/driver_bsd.c

@@ -648,7 +648,7 @@ rtbuf_len(void)
 		len = 2048;
 	}
 
-	return len;
+	return (len == 0) ? 2048 : len;
 }
 
 #ifdef HOSTAPD