Subject: [PATCH] vlan: fix the bug that cannot create vlan4095

From: Huang Qijun <[email-masked]>
Date: Mon, 18 May 2020 13:27:55 +0800

According to the 8021q standard, the VLAN id range is 1 to 4095.
But in the register_vlan_device function, the range is 1 to 4094,
because ">= VLAN_VID_MASK" is used to determine whether the id
is illegal. This will prevent the creation of the vlan4095 interface:
    $ vconfig add sit0 4095
    vconfig: ioctl error for add: Numerical result out of range

To fix this error, this patch uses ">= VLAN_N_VID" instead to
determine if the id is illegal.

Signed-off-by: Huang Qijun <[email-masked]>
---
 net/8021q/vlan.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/net/8021q/vlan.c b/net/8021q/vlan.c
index d4bcfd8f95bf..5de7861ddf64 100644
--- a/net/8021q/vlan.c
+++ b/net/8021q/vlan.c
@@ -219,7 +219,7 @@ static int register_vlan_device(struct net_device *real_dev, u16 vlan_id)
 	char name[IFNAMSIZ];
 	int err;
 
-	if (vlan_id >= VLAN_VID_MASK)
+	if (vlan_id >= VLAN_N_VID)
 		return -ERANGE;
 
 	err = vlan_check_real_dev(real_dev, htons(ETH_P_8021Q), vlan_id,
-- 
2.17.1