ethtool: strset: allow ETHTOOL_A_STRSET_COUNTS_ONLY attr

The ETHTOOL_A_STRSET_COUNTS_ONLY flag attribute was previously
not allowed to be used, but now due to the policy size reduction
we would access the tb[] array out of bounds since we tried to
check for the attribute despite it not being accepted.

Fix both issues by adding it correctly to the appropriate policy.

Fixes: ff419afa4310 ("ethtool: trim policy tables")
Fixes: 71921690f974 ("ethtool: provide string sets with STRSET_GET request")
Reported-by: Leon Romanovsky <[e-mail]>
Signed-off-by: Johannes Berg <[e-mail]>
Tested-by: Leon Romanovsky <[e-mail]>
Reviewed-by: Jakub Kicinski <[e-mail]>
Signed-off-by: Jakub Kicinski <[e-mail]>

net/ethtool/netlink.h

···
 
 extern const struct nla_policy ethnl_header_policy[ETHTOOL_A_HEADER_FLAGS + 1];
 extern const struct nla_policy ethnl_header_policy_stats[ETHTOOL_A_HEADER_FLAGS + 1];
-extern const struct nla_policy ethnl_strset_get_policy[ETHTOOL_A_STRSET_STRINGSETS + 1];
+extern const struct nla_policy ethnl_strset_get_policy[ETHTOOL_A_STRSET_COUNTS_ONLY + 1];
 extern const struct nla_policy ethnl_linkinfo_get_policy[ETHTOOL_A_LINKINFO_HEADER + 1];
 extern const struct nla_policy ethnl_linkinfo_set_policy[ETHTOOL_A_LINKINFO_TP_MDIX_CTRL + 1];
 extern const struct nla_policy ethnl_linkmodes_get_policy[ETHTOOL_A_LINKMODES_HEADER + 1];

net/ethtool/strset.c

···
 	[ETHTOOL_A_STRSET_HEADER]	=
 		NLA_POLICY_NESTED(ethnl_header_policy),
 	[ETHTOOL_A_STRSET_STRINGSETS]	= { .type = NLA_NESTED },
+	[ETHTOOL_A_STRSET_COUNTS_ONLY]	= { .type = NLA_FLAG },
 };
 
 static const struct nla_policy get_stringset_policy[] = {