Re: [PATCH v1 net-next 12/13] rtnetlink: Call rtnl_link_get_net_capable() in do_setlink().

[kernel test robot <lkp@intel.com>]

Hi Kuniyuki,

kernel test robot noticed the following build warnings:

[auto build test WARNING on net-next/main]

url:    https://github.com/intel-lab-lkp/linux/commits/Kuniyuki-Iwashima/rtnetlink-Allocate-linkinfo-as-struct-rtnl_newlink_tbs/20241010-072158
base:   net-next/main
patch link:    https://lore.kernel.org/r/20241009231656.57830-13-kuniyu%40amazon.com
patch subject: [PATCH v1 net-next 12/13] rtnetlink: Call rtnl_link_get_net_capable() in do_setlink().
config: x86_64-buildonly-randconfig-003-20241011 (https://download.01.org/0day-ci/archive/20241011/202410111515.TbOH4hSS-lkp@intel.com/config)
compiler: clang version 18.1.8 (https://github.com/llvm/llvm-project 3b5b5c1ec4a3095ab096dd780e84d7ab81f3d7ff)
reproduce (this is a W=1 build): (https://download.01.org/0day-ci/archive/20241011/202410111515.TbOH4hSS-lkp@intel.com/reproduce)

If you fix the issue in a separate patch/commit (i.e. not just a new version of
the same patch/commit), kindly add following tags
| Reported-by: kernel test robot <lkp@intel.com>
| Closes: https://lore.kernel.org/oe-kbuild-all/202410111515.TbOH4hSS-lkp@intel.com/

All warnings (new ones prefixed by >>):

>> net/core/rtnetlink.c:3281:6: warning: variable 'tgt_net' is used uninitialized whenever 'if' condition is true [-Wsometimes-uninitialized]
    3281 |         if (err < 0)
         |             ^~~~~~~
   net/core/rtnetlink.c:3301:10: note: uninitialized use occurs here
    3301 |         put_net(tgt_net);
         |                 ^~~~~~~
   net/core/rtnetlink.c:3281:2: note: remove the 'if' if its condition is always false
    3281 |         if (err < 0)
         |         ^~~~~~~~~~~~
    3282 |                 goto errout;
         |                 ~~~~~~~~~~~
   net/core/rtnetlink.c:3277:6: warning: variable 'tgt_net' is used uninitialized whenever 'if' condition is true [-Wsometimes-uninitialized]
    3277 |         if (err < 0)
         |             ^~~~~~~
   net/core/rtnetlink.c:3301:10: note: uninitialized use occurs here
    3301 |         put_net(tgt_net);
         |                 ^~~~~~~
   net/core/rtnetlink.c:3277:2: note: remove the 'if' if its condition is always false
    3277 |         if (err < 0)
         |         ^~~~~~~~~~~~
    3278 |                 goto errout;
         |                 ~~~~~~~~~~~
   net/core/rtnetlink.c:3272:21: note: initialize the variable 'tgt_net' to silence this warning
    3272 |         struct net *tgt_net;
         |                            ^
         |                             = NULL
   2 warnings generated.


vim +3281 net/core/rtnetlink.c

cc6090e985d7d6 Jiri Pirko        2019-09-30  3264  
c21ef3e343ae91 David Ahern       2017-04-16  3265  static int rtnl_setlink(struct sk_buff *skb, struct nlmsghdr *nlh,
c21ef3e343ae91 David Ahern       2017-04-16  3266  			struct netlink_ext_ack *extack)
0157f60c0caea2 Patrick McHardy   2007-06-13  3267  {
3a6cb17da69fbf Kuniyuki Iwashima 2024-10-09  3268  	struct ifinfomsg *ifm = nlmsg_data(nlh);
3b1e0a655f8eba YOSHIFUJI Hideaki 2008-03-26  3269  	struct net *net = sock_net(skb->sk);
0157f60c0caea2 Patrick McHardy   2007-06-13  3270  	struct nlattr *tb[IFLA_MAX+1];
3a6cb17da69fbf Kuniyuki Iwashima 2024-10-09  3271  	struct net_device *dev = NULL;
b27f78e2575aa2 Kuniyuki Iwashima 2024-10-09  3272  	struct net *tgt_net;
3a6cb17da69fbf Kuniyuki Iwashima 2024-10-09  3273  	int err;
0157f60c0caea2 Patrick McHardy   2007-06-13  3274  
8cb081746c031f Johannes Berg     2019-04-26  3275  	err = nlmsg_parse_deprecated(nlh, sizeof(*ifm), tb, IFLA_MAX,
8cb081746c031f Johannes Berg     2019-04-26  3276  				     ifla_policy, extack);
0157f60c0caea2 Patrick McHardy   2007-06-13  3277  	if (err < 0)
0157f60c0caea2 Patrick McHardy   2007-06-13  3278  		goto errout;
0157f60c0caea2 Patrick McHardy   2007-06-13  3279  
4ff66cae7f10b6 Christian Brauner 2018-02-07  3280  	err = rtnl_ensure_unique_netns(tb, extack, false);
4ff66cae7f10b6 Christian Brauner 2018-02-07 @3281  	if (err < 0)
4ff66cae7f10b6 Christian Brauner 2018-02-07  3282  		goto errout;
4ff66cae7f10b6 Christian Brauner 2018-02-07  3283  
b27f78e2575aa2 Kuniyuki Iwashima 2024-10-09  3284  	tgt_net = rtnl_link_get_net_capable(skb, net, tb, CAP_NET_ADMIN);
b27f78e2575aa2 Kuniyuki Iwashima 2024-10-09  3285  	if (IS_ERR(tgt_net))
b27f78e2575aa2 Kuniyuki Iwashima 2024-10-09  3286  		return PTR_ERR(tgt_net);
b27f78e2575aa2 Kuniyuki Iwashima 2024-10-09  3287  
0157f60c0caea2 Patrick McHardy   2007-06-13  3288  	if (ifm->ifi_index > 0)
a3d1289126e7b1 Eric Dumazet      2009-10-21  3289  		dev = __dev_get_by_index(net, ifm->ifi_index);
76c9ac0ee878f6 Jiri Pirko        2019-09-30  3290  	else if (tb[IFLA_IFNAME] || tb[IFLA_ALT_IFNAME])
5ea08b5286f66e Florent Fourcot   2022-04-15  3291  		dev = rtnl_dev_get(net, tb);
0157f60c0caea2 Patrick McHardy   2007-06-13  3292  	else
3a6cb17da69fbf Kuniyuki Iwashima 2024-10-09  3293  		err = -EINVAL;
0157f60c0caea2 Patrick McHardy   2007-06-13  3294  
3a6cb17da69fbf Kuniyuki Iwashima 2024-10-09  3295  	if (dev)
b27f78e2575aa2 Kuniyuki Iwashima 2024-10-09  3296  		err = do_setlink(skb, dev, tgt_net, ifm, extack, tb, 0);
3a6cb17da69fbf Kuniyuki Iwashima 2024-10-09  3297  	else if (!err)
0157f60c0caea2 Patrick McHardy   2007-06-13  3298  		err = -ENODEV;
0157f60c0caea2 Patrick McHardy   2007-06-13  3299  
da5e0494c542dd Thomas Graf       2006-08-10  3300  errout:
b27f78e2575aa2 Kuniyuki Iwashima 2024-10-09  3301  	put_net(tgt_net);
b27f78e2575aa2 Kuniyuki Iwashima 2024-10-09  3302  
^1da177e4c3f41 Linus Torvalds    2005-04-16  3303  	return err;
^1da177e4c3f41 Linus Torvalds    2005-04-16  3304  }
^1da177e4c3f41 Linus Torvalds    2005-04-16  3305  

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