Index: bpf.c
===================================================================
RCS file: /cvs/src/sys/net/bpf.c,v
retrieving revision 1.203
diff -u -p -r1.203 bpf.c
--- bpf.c	21 Jan 2021 12:33:14 -0000	1.203
+++ bpf.c	21 Apr 2021 00:03:15 -0000
@@ -1222,6 +1222,7 @@ int
 filt_bpfread(struct knote *kn, long hint)
 {
 	struct bpf_d *d = kn->kn_hook;
+	struct bpf_if *bp;
 
 	KERNEL_ASSERT_LOCKED();
 
@@ -1229,9 +1230,11 @@ filt_bpfread(struct knote *kn, long hint
 	kn->kn_data = d->bd_hlen;
 	if (d->bd_immediate)
 		kn->kn_data += d->bd_slen;
+
+	bp = d->bd_bif; /* check that the interface is still attached */
 	mtx_leave(&d->bd_mtx);
 
-	return (kn->kn_data > 0);
+	return (kn->kn_data > 0 || bp == NULL);
 }
 
 /*
Index: if_tun.c
===================================================================
RCS file: /cvs/src/sys/net/if_tun.c,v
retrieving revision 1.231
diff -u -p -r1.231 if_tun.c
--- if_tun.c	9 Mar 2021 20:05:14 -0000	1.231
+++ if_tun.c	21 Apr 2021 00:03:15 -0000
@@ -1029,7 +1029,7 @@ filt_tunread(struct knote *kn, long hint
 
 	kn->kn_data = ifq_hdatalen(&ifp->if_snd);
 
-	return (kn->kn_data > 0);
+	return (kn->kn_data > 0 || sc->sc_dev == 0);
 }
 
 void