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From 356b67db7834c4a1f2c5e3caad8c18e71f046c24 Mon Sep 17 00:00:00 2001
From: Linus Walleij <linus.walleij@linaro.org>
Date: Sun, 26 Sep 2021 00:59:27 +0200
Subject: [PATCH] net: dsa: rtl8366rb: Fix off-by-one bug
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Git-commit: 5f5f12f5d4b108399130bb5c11f07765851d9cdb
Patch-mainline: v5.16-rc1
References: stable-5.14.19

[ Upstream commit 5f5f12f5d4b108399130bb5c11f07765851d9cdb ]

The max VLAN number with non-4K VLAN activated is 15, and the
range is 0..15. Not 16.

The impact should be low since we by default have 4K VLAN and
thus have 4095 VLANs to play with in this switch. There will
not be a problem unless the code is rewritten to only use
16 VLANs.

Fixes: d8652956cf37 ("net: dsa: realtek-smi: Add Realtek SMI driver")
Cc: Mauri Sandberg <sandberg@mailfence.com>
Cc: DENG Qingfang <dqfext@gmail.com>
Cc: Florian Fainelli <f.fainelli@gmail.com>
Reviewed-by: Alvin Šipraga <alsi@bang-olufsen.dk>
Reviewed-by: Vladimir Oltean <olteanv@gmail.com>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
Reviewed-by: Florian Fainelli <f.fainelli@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Sasha Levin <sashal@kernel.org>
Acked-by: Takashi Iwai <tiwai@suse.de>

---
 drivers/net/dsa/rtl8366rb.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/net/dsa/rtl8366rb.c b/drivers/net/dsa/rtl8366rb.c
index a89093bc6c6a..9e3b572ed999 100644
--- a/drivers/net/dsa/rtl8366rb.c
+++ b/drivers/net/dsa/rtl8366rb.c
@@ -1350,7 +1350,7 @@ static int rtl8366rb_set_mc_index(struct realtek_smi *smi, int port, int index)
 
 static bool rtl8366rb_is_vlan_valid(struct realtek_smi *smi, unsigned int vlan)
 {
-	unsigned int max = RTL8366RB_NUM_VLANS;
+	unsigned int max = RTL8366RB_NUM_VLANS - 1;
 
 	if (smi->vlan4k_enabled)
 		max = RTL8366RB_NUM_VIDS - 1;
-- 
2.26.2