netlbl_unlabel_addrinfo_get() used the address attribute length to
determine whether the attribute data could be read as an IPv4 or IPv6
address, but did not independently validate the corresponding mask
attribute length. A crafted Generic Netlink request could therefore
provide a valid IPv4/IPv6 address attribute with a shorter mask
attribute, which would later be read as a full struct in_addr or
struct in6_addr.
NLA_BINARY policy lengths are maximum lengths by default, so use
NLA_POLICY_EXACT_LEN() for the unlabeled IPv4/IPv6 address and mask
attributes. This rejects short attributes during policy validation and
also exposes the exact length requirements through policy introspection.
Fixes: 8cc44579d1 ("NetLabel: Introduce static network labels for unlabeled connections")
Signed-off-by: Chenguang Zhao <zhaochenguang@kylinos.cn>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
9772589b57