[PATCH net v4 3/8] net: dsa: b53: clear stale state when creating an ARL entry

[Florian Fainelli <florian.fainelli@broadcom.com>]

When an ARL lookup does not find the requested MAC and VID, b53_arl_read()
returns the first free bin index but leaves the entry populated with the
last bin examined. The multicast add path then ORs the requested port into
that unrelated entry's forwarding bitmap, potentially forwarding packets
to ports which are not members of the multicast group.

Clear the entry before creating a new one. Also return without writing
anything when deleting an entry which is not present, instead of making
a new entry from stale bin contents.

Deleting an entry which is not present now returns -ENOENT, including
when the lookup ran out of space (-ENOSPC), where it previously returned
0 in that case.

Fixes: 5d65b64a3d97 ("net: dsa: b53: Add support for MDB")
Signed-off-by: Florian Fainelli <florian.fainelli@broadcom.com>
---
 drivers/net/dsa/b53/b53_common.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/drivers/net/dsa/b53/b53_common.c b/drivers/net/dsa/b53/b53_common.c
index ca2ba8c157b7..cc42b2a4870a 100644
--- a/drivers/net/dsa/b53/b53_common.c
+++ b/drivers/net/dsa/b53/b53_common.c
@@ -2055,9 +2055,13 @@ static int b53_arl_op(struct b53_device *dev, int op, int port,
 			addr, vid);
 		return is_valid ? ret : 0;
 	case -ENOENT:
+		if (!is_valid)
+			return 0;
+
 		/* We could not find a matching MAC, so reset to a new entry */
 		dev_dbg(dev->dev, "{%pM,%.4d} not found, using idx: %d\n",
 			addr, vid, idx);
+		memset(&ent, 0, sizeof(ent));
 		break;
 	default:
 		dev_dbg(dev->dev, "{%pM,%.4d} found, using idx: %d\n",
-- 
2.53.0