neighbour: allow NUD_NOARP entries to be forced GCed

IFF_POINTOPOINT interfaces use NUD_NOARP entries for IPv6. It's possible to
fill up the neighbour table with enough entries that it will overflow for
valid connections after that.

This behaviour is more prevalent after commit 58956317c8de ("neighbor:
Improve garbage collection") is applied, as it prevents removal from
entries that are not NUD_FAILED, unless they are more than 5s old.

Fixes: 58956317c8de (neighbor: Improve garbage collection)
Reported-by: Kasper Dupont <kasperd@gjkwv.06.feb.2021.kasperd.net>
Signed-off-by: Thadeu Lima de Souza Cascardo <cascardo@canonical.com>
Signed-off-by: David Ahern <dsahern@kernel.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/net/core/neighbour.c b/net/core/neighbour.c
index 98f20efbfadf26a6bcaa894445f482043dfc3716..bf774575ad7169800a1a1357eb290e8b0d3f25fe 100644 (file)
--- a/net/core/neighbour.c
+++ b/net/core/neighbour.c
@@ -238,6 +238,7 @@ static int neigh_forced_gc(struct neigh_table *tbl)
 
                        write_lock(&n->lock);
                        if ((n->nud_state == NUD_FAILED) ||
+                           (n->nud_state == NUD_NOARP) ||
                            (tbl->is_multicast &&
                             tbl->is_multicast(n->primary_key)) ||
                            time_after(tref, n->updated))