openvswitch: Stricter validation for the userspace action

This change enhances the robustness of validate_userspace() by ensuring
that all Netlink attributes are fully contained within the parent
attribute. The previous use of nla_parse_nested_deprecated() could
silently skip trailing or malformed attributes, as it stops parsing at
the first invalid entry.

By switching to nla_parse_deprecated_strict(), we make sure only fully
validated attributes are copied for later use.

Signed-off-by: Eelco Chaudron <[e-mail]>
Reviewed-by: Simon Horman <[e-mail]>
Acked-by: Ilya Maximets <[e-mail]>
Link: https://patch.msgid.link/[e-mail]
Signed-off-by: Jakub Kicinski <[e-mail]>

net/openvswitch/flow_netlink.c

···
 	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;