Re: net/mptcp/pm_netlink.c:1169 mptcp_pm_parse_pm_addr_attr() warn: missing error code? 'err'

Mat Martineau
2022-12-02T23:38:15Z

On Fri, 2 Dec 2022, Dan Carpenter wrote:

> tree: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git master
> head: a4412fdd49dc011bcc2c0d81ac4cab7457092650
> commit: 982f17ba1a2534b878fbcb1a5273bfbc551c5397 mptcp: netlink: split mptcp_pm_parse_addr into two functions
> config: i386-randconfig-m021
> compiler: gcc-11 (Debian 11.3.0-8) 11.3.0
>
> If you fix the issue, kindly add following tag where applicable
> | Reported-by: kernel test robot <lkp@intel.com>
> | Reported-by: Dan Carpenter <error27@gmail.com>
>
> smatch warnings:
> net/mptcp/pm_netlink.c:1169 mptcp_pm_parse_pm_addr_attr() warn: missing error code? 'err'
>
> vim +/err +1169 net/mptcp/pm_netlink.c
>
> 982f17ba1a2534 Florian Westphal 2022-05-03 1145 static int mptcp_pm_parse_pm_addr_attr(struct nlattr *tb[],
> 982f17ba1a2534 Florian Westphal 2022-05-03 1146 const struct nlattr *attr,
> 982f17ba1a2534 Florian Westphal 2022-05-03 1147 struct genl_info *info,
> 982f17ba1a2534 Florian Westphal 2022-05-03 1148 struct mptcp_addr_info *addr,
> 982f17ba1a2534 Florian Westphal 2022-05-03 1149 bool require_family)
> 01cacb00b35cb6 Paolo Abeni 2020-03-27 1150 {
> 01cacb00b35cb6 Paolo Abeni 2020-03-27 1151 int err, addr_addr;
> 01cacb00b35cb6 Paolo Abeni 2020-03-27 1152
> 01cacb00b35cb6 Paolo Abeni 2020-03-27 1153 if (!attr) {
> 01cacb00b35cb6 Paolo Abeni 2020-03-27 1154 GENL_SET_ERR_MSG(info, "missing address info");
> 01cacb00b35cb6 Paolo Abeni 2020-03-27 1155 return -EINVAL;
> 01cacb00b35cb6 Paolo Abeni 2020-03-27 1156 }
> 01cacb00b35cb6 Paolo Abeni 2020-03-27 1157
> 01cacb00b35cb6 Paolo Abeni 2020-03-27 1158 /* no validation needed - was already done via nested policy */
> 01cacb00b35cb6 Paolo Abeni 2020-03-27 1159 err = nla_parse_nested_deprecated(tb, MPTCP_PM_ADDR_ATTR_MAX, attr,
> 01cacb00b35cb6 Paolo Abeni 2020-03-27 1160 mptcp_pm_addr_policy, info->extack);
> 01cacb00b35cb6 Paolo Abeni 2020-03-27 1161 if (err)
> 01cacb00b35cb6 Paolo Abeni 2020-03-27 1162 return err;
> 01cacb00b35cb6 Paolo Abeni 2020-03-27 1163
> 982f17ba1a2534 Florian Westphal 2022-05-03 1164 if (tb[MPTCP_PM_ADDR_ATTR_ID])
> 982f17ba1a2534 Florian Westphal 2022-05-03 1165 addr->id = nla_get_u8(tb[MPTCP_PM_ADDR_ATTR_ID]);
> 982f17ba1a2534 Florian Westphal 2022-05-03 1166
> 01cacb00b35cb6 Paolo Abeni 2020-03-27 1167 if (!tb[MPTCP_PM_ADDR_ATTR_FAMILY]) {
> 01cacb00b35cb6 Paolo Abeni 2020-03-27 1168 if (!require_family)
> 982f17ba1a2534 Florian Westphal 2022-05-03 @1169 return err;
>
> "err" is zero at this point. Presumably a negative error code was
> intended.

Hi Dan -

The intended error code is 0 here: the return happens if no
MPTCP_PM_ADDR_ATTR_FAMILY value is present and require_family is false.

It would be clearer to "return 0;", but the code is working as expected.

Could you be sure to cc mptcp@lists.linux.dev and
matthieu.baerts@tessares.net for future MPTCP issues?

Thanks,

Mat

>
> 01cacb00b35cb6 Paolo Abeni 2020-03-27 1170
> 01cacb00b35cb6 Paolo Abeni 2020-03-27 1171 NL_SET_ERR_MSG_ATTR(info->extack, attr,
> 01cacb00b35cb6 Paolo Abeni 2020-03-27 1172 "missing family");
> 01cacb00b35cb6 Paolo Abeni 2020-03-27 1173 return -EINVAL;
> 01cacb00b35cb6 Paolo Abeni 2020-03-27 1174 }
> 01cacb00b35cb6 Paolo Abeni 2020-03-27 1175
> 982f17ba1a2534 Florian Westphal 2022-05-03 1176 addr->family = nla_get_u16(tb[MPTCP_PM_ADDR_ATTR_FAMILY]);
> 982f17ba1a2534 Florian Westphal 2022-05-03 1177 if (addr->family != AF_INET
> 01cacb00b35cb6 Paolo Abeni 2020-03-27 1178 #if IS_ENABLED(CONFIG_MPTCP_IPV6)
> 982f17ba1a2534 Florian Westphal 2022-05-03 1179 && addr->family != AF_INET6
> 01cacb00b35cb6 Paolo Abeni 2020-03-27 1180 #endif
> 01cacb00b35cb6 Paolo Abeni 2020-03-27 1181 ) {
> 01cacb00b35cb6 Paolo Abeni 2020-03-27 1182 NL_SET_ERR_MSG_ATTR(info->extack, attr,
> 01cacb00b35cb6 Paolo Abeni 2020-03-27 1183 "unknown address family");
> 01cacb00b35cb6 Paolo Abeni 2020-03-27 1184 return -EINVAL;
> 01cacb00b35cb6 Paolo Abeni 2020-03-27 1185 }
> 982f17ba1a2534 Florian Westphal 2022-05-03 1186 addr_addr = mptcp_pm_family_to_addr(addr->family);
> 01cacb00b35cb6 Paolo Abeni 2020-03-27 1187 if (!tb[addr_addr]) {
> 01cacb00b35cb6 Paolo Abeni 2020-03-27 1188 NL_SET_ERR_MSG_ATTR(info->extack, attr,
> 01cacb00b35cb6 Paolo Abeni 2020-03-27 1189 "missing address data");
> 01cacb00b35cb6 Paolo Abeni 2020-03-27 1190 return -EINVAL;
> 01cacb00b35cb6 Paolo Abeni 2020-03-27 1191 }
>
> --
> 0-DAY CI Kernel Test Service
> https://01.org/lkp
>
>

--
Mat Martineau
Intel