Index: sys/compat/linux/linux.c
===================================================================
--- sys/compat/linux/linux.c
+++ sys/compat/linux/linux.c
@@ -227,18 +227,23 @@
 	struct ifnet *ifp;
 	int len, unit;
 	char *ep;
-	int is_eth, index;
+	int index;
+	bool is_eth, is_lo;
 
 	for (len = 0; len < LINUX_IFNAMSIZ; ++len)
-		if (!isalpha(lxname[len]))
+		if (isalpha(lxname[len]) == 0 || lxname[len] == 0)
 			break;
 	if (len == 0 || len == LINUX_IFNAMSIZ)
 		return (NULL);
+	/* Linux loopback interface name is lo (not lo0) */
+	is_lo = (len == 2 && strncmp(lxname, "lo", len) == 0);
 	unit = (int)strtoul(lxname + len, &ep, 10);
-	if (ep == NULL || ep == lxname + len || ep >= lxname + LINUX_IFNAMSIZ)
+	if ((ep == NULL || ep == lxname + len || ep >= lxname + LINUX_IFNAMSIZ) &&
+	    is_lo == 0)
 		return (NULL);
 	index = 0;
-	is_eth = (len == 3 && !strncmp(lxname, "eth", len)) ? 1 : 0;
+	is_eth = (len == 3 && strncmp(lxname, "eth", len) == 0);
+
 	CURVNET_SET(TD_TO_VNET(td));
 	IFNET_RLOCK();
 	CK_STAILQ_FOREACH(ifp, &V_ifnet, if_link) {
@@ -251,10 +256,12 @@
 			break;
 		if (is_eth && IFP_IS_ETH(ifp) && unit == index++)
 			break;
+		if (is_lo && IFP_IS_LOOP(ifp))
+			break;
 	}
 	IFNET_RUNLOCK();
 	CURVNET_RESTORE();
-	if (ifp != NULL)
+	if (ifp != NULL && bsdname != NULL)
 		strlcpy(bsdname, ifp->if_xname, IFNAMSIZ);
 	return (ifp);
 }
@@ -302,6 +309,3 @@
 
 	return (ENOENT);
 }
-
-
-