Re: [PATCH] netfilter: tproxy: Add RCU protection in nf_tproxy_laddr4

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

Hi Jiawei,

kernel test robot noticed the following build warnings:

[auto build test WARNING on netfilter-nf/main]
[also build test WARNING on linus/master v6.11-rc6 next-20240905]
[cannot apply to nf-next/master horms-ipvs/master]
[If your patch is applied to the wrong git tree, kindly drop us a note.
And when submitting patch, we suggest to use '--base' as documented in
https://git-scm.com/docs/git-format-patch#_base_tree_information]

url:    https://github.com/intel-lab-lkp/linux/commits/Jiawei-Ye/netfilter-tproxy-Add-RCU-protection-in-nf_tproxy_laddr4/20240904-202126
base:   https://git.kernel.org/pub/scm/linux/kernel/git/netfilter/nf.git main
patch link:    https://lore.kernel.org/r/tencent_DE4D2D0FE82F3CA9294AEEB3A949A44F6008%40qq.com
patch subject: [PATCH] netfilter: tproxy: Add RCU protection in nf_tproxy_laddr4
config: m68k-allmodconfig (https://download.01.org/0day-ci/archive/20240905/202409052334.kT8sZWuh-lkp@intel.com/config)
compiler: m68k-linux-gcc (GCC) 14.1.0
reproduce (this is a W=1 build): (https://download.01.org/0day-ci/archive/20240905/202409052334.kT8sZWuh-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/202409052334.kT8sZWuh-lkp@intel.com/

All warnings (new ones prefixed by >>):

   net/ipv4/netfilter/nf_tproxy_ipv4.c: In function 'nf_tproxy_laddr4':
>> net/ipv4/netfilter/nf_tproxy_ipv4.c:62:9: warning: this 'if' clause does not guard... [-Wmisleading-indentation]
      62 |         if (!indev)
         |         ^~
   net/ipv4/netfilter/nf_tproxy_ipv4.c:64:17: note: ...this statement, but the latter is misleadingly indented as if it were guarded by the 'if'
      64 |                 return daddr;
         |                 ^~~~~~


vim +/if +62 net/ipv4/netfilter/nf_tproxy_ipv4.c

45ca4e0cf2734f Máté Eckl        2018-06-01  49  
45ca4e0cf2734f Máté Eckl        2018-06-01  50  __be32 nf_tproxy_laddr4(struct sk_buff *skb, __be32 user_laddr, __be32 daddr)
45ca4e0cf2734f Máté Eckl        2018-06-01  51  {
b8d19572367bb0 Florian Westphal 2019-05-31  52  	const struct in_ifaddr *ifa;
45ca4e0cf2734f Máté Eckl        2018-06-01  53  	struct in_device *indev;
45ca4e0cf2734f Máté Eckl        2018-06-01  54  	__be32 laddr;
45ca4e0cf2734f Máté Eckl        2018-06-01  55  
45ca4e0cf2734f Máté Eckl        2018-06-01  56  	if (user_laddr)
45ca4e0cf2734f Máté Eckl        2018-06-01  57  		return user_laddr;
45ca4e0cf2734f Máté Eckl        2018-06-01  58  
45ca4e0cf2734f Máté Eckl        2018-06-01  59  	laddr = 0;
2729675b33a93a Jiawei Ye        2024-09-04  60  	rcu_read_lock();
45ca4e0cf2734f Máté Eckl        2018-06-01  61  	indev = __in_dev_get_rcu(skb->dev);
21a673bddc8fd4 Florian Westphal 2024-05-13 @62  	if (!indev)
2729675b33a93a Jiawei Ye        2024-09-04  63  		rcu_read_unlock();
21a673bddc8fd4 Florian Westphal 2024-05-13  64  		return daddr;
b8d19572367bb0 Florian Westphal 2019-05-31  65  
b8d19572367bb0 Florian Westphal 2019-05-31  66  	in_dev_for_each_ifa_rcu(ifa, indev) {
b8d19572367bb0 Florian Westphal 2019-05-31  67  		if (ifa->ifa_flags & IFA_F_SECONDARY)
b8d19572367bb0 Florian Westphal 2019-05-31  68  			continue;
b8d19572367bb0 Florian Westphal 2019-05-31  69  
45ca4e0cf2734f Máté Eckl        2018-06-01  70  		laddr = ifa->ifa_local;
45ca4e0cf2734f Máté Eckl        2018-06-01  71  		break;
b8d19572367bb0 Florian Westphal 2019-05-31  72  	}
2729675b33a93a Jiawei Ye        2024-09-04  73  	rcu_read_unlock();
45ca4e0cf2734f Máté Eckl        2018-06-01  74  
45ca4e0cf2734f Máté Eckl        2018-06-01  75  	return laddr ? laddr : daddr;
45ca4e0cf2734f Máté Eckl        2018-06-01  76  }
45ca4e0cf2734f Máté Eckl        2018-06-01  77  EXPORT_SYMBOL_GPL(nf_tproxy_laddr4);
45ca4e0cf2734f Máté Eckl        2018-06-01  78  

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