netdev - [PATCH net-next] openvswitch: Fix userspace attribute length validation

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Message-ID: <051302b5ef5e5ac8801bbef5a20ef2ab15b997a2.1746696747.git.echaudro@redhat.com>
Date: Thu,  8 May 2025 11:32:27 +0200
From: Eelco Chaudron <echaudro@...hat.com>
To: netdev@...r.kernel.org
Cc: dev@...nvswitch.org,
	aconole@...hat.com,
	echaudro@...hat.com,
	i.maximets@....org,
	davem@...emloft.net,
	edumazet@...gle.com,
	kuba@...nel.org,
	pabeni@...hat.com,
	horms@...nel.org
Subject: [PATCH net-next] openvswitch: Fix userspace attribute length validation

The current implementation of validate_userspace() does not verify
whether all Netlink attributes fit within the parent attribute. This
is because nla_parse_nested_deprecated() stops processing Netlink
attributes as soon as an invalid one is encountered.

To address this, we use nla_parse_deprecated_strict() which will
return an error upon encountering attributes with an invalid size.

Fixes: ccb1352e76cf ("net: Add Open vSwitch kernel components.")
Signed-off-by: Eelco Chaudron <echaudro@...hat.com>
---
 net/openvswitch/flow_netlink.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/net/openvswitch/flow_netlink.c b/net/openvswitch/flow_netlink.c
index 518be23e48ea..ad64bb9ab5e2 100644
--- a/net/openvswitch/flow_netlink.c
+++ b/net/openvswitch/flow_netlink.c
@@ -3049,7 +3049,8 @@ static int validate_userspace(const struct nlattr *attr)
 	struct nlattr *a[OVS_USERSPACE_ATTR_MAX + 1];
 	int error;
 
-	error = nla_parse_nested_deprecated(a, OVS_USERSPACE_ATTR_MAX, attr,
+	error = nla_parse_deprecated_strict(a, OVS_USERSPACE_ATTR_MAX,
+					    nla_data(attr), nla_len(attr),
 					    userspace_policy, NULL);
 	if (error)
 		return error;
-- 
2.47.1