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From: Lin Ma <linma@zju.edu.cn>
To: davem@davemloft.net,
	edumazet@google.com,
	kuba@kernel.org,
	pabeni@redhat.com,
	linma@zju.edu.cn,
	netdev@vger.kernel.org,
	linux-kernel@vger.kernel.org
Subject: [PATCH net v2] vlan: skip nested type that is not IFLA_VLAN_QOS_MAPPING
Date: Thu, 18 Jan 2024 21:03:06 +0800
Message-Id: <20240118130306.1644001-1-linma@zju.edu.cn>
Precedence: bulk

In the vlan_changelink function, a loop is used to parse the nested
attributes IFLA_VLAN_EGRESS_QOS and IFLA_VLAN_INGRESS_QOS in order to
obtain the struct ifla_vlan_qos_mapping. These two nested attributes are
checked in the vlan_validate_qos_map function, which calls
nla_validate_nested_deprecated with the vlan_map_policy.

However, this deprecated validator applies a LIBERAL strictness, allowing
the presence of an attribute with the type IFLA_VLAN_QOS_UNSPEC.
Consequently, the loop in vlan_changelink may parse an attribute of type
IFLA_VLAN_QOS_UNSPEC and believe it carries a payload of
struct ifla_vlan_qos_mapping, which is not necessarily true.

To address this issue and ensure compatibility, this patch introduces two
type checks that skip attributes whose type is not IFLA_VLAN_QOS_MAPPING.

Fixes: 07b5b17e157b ("[VLAN]: Use rtnl_link API")
Signed-off-by: Lin Ma <linma@zju.edu.cn>
---
V1 -> V2: make net-next to net as suggested by Paolo
          and add Fixes tag for this one

 net/8021q/vlan_netlink.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/net/8021q/vlan_netlink.c b/net/8021q/vlan_netlink.c
index 214532173536..a3b68243fd4b 100644
--- a/net/8021q/vlan_netlink.c
+++ b/net/8021q/vlan_netlink.c
@@ -118,12 +118,16 @@ static int vlan_changelink(struct net_device *dev, struct nlattr *tb[],
 	}
 	if (data[IFLA_VLAN_INGRESS_QOS]) {
 		nla_for_each_nested(attr, data[IFLA_VLAN_INGRESS_QOS], rem) {
+			if (nla_type(attr) != IFLA_VLAN_QOS_MAPPING)
+				continue;
 			m = nla_data(attr);
 			vlan_dev_set_ingress_priority(dev, m->to, m->from);
 		}
 	}
 	if (data[IFLA_VLAN_EGRESS_QOS]) {
 		nla_for_each_nested(attr, data[IFLA_VLAN_EGRESS_QOS], rem) {
+			if (nla_type(attr) != IFLA_VLAN_QOS_MAPPING)
+				continue;
 			m = nla_data(attr);
 			err = vlan_dev_set_egress_priority(dev, m->from, m->to);
 			if (err)
-- 
2.17.1