Re: [PATCH net-next] icmp: Add icmp_timestamp_ignore_all to control ICMP_TIMESTAMP

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

Hi,

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/ye-xingchen-zte-com-cn/icmp-Add-icmp_timestamp_ignore_all-to-control-ICMP_TIMESTAMP/20240517-172903
base:   net-next/main
patch link:    https://lore.kernel.org/r/20240517172639229ec5bN7VBV7SGEHkSK5K6f%40zte.com.cn
patch subject: [PATCH net-next] icmp: Add icmp_timestamp_ignore_all to control ICMP_TIMESTAMP
config: arm-clps711x_defconfig (https://download.01.org/0day-ci/archive/20240518/202405180545.RQgwvazz-lkp@intel.com/config)
compiler: clang version 19.0.0git (https://github.com/llvm/llvm-project fa9b1be45088dce1e4b602d451f118128b94237b)
reproduce (this is a W=1 build): (https://download.01.org/0day-ci/archive/20240518/202405180545.RQgwvazz-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/202405180545.RQgwvazz-lkp@intel.com/

All warnings (new ones prefixed by >>):

   In file included from net/ipv4/icmp.c:69:
   In file included from include/linux/inet.h:42:
   In file included from include/net/net_namespace.h:43:
   In file included from include/linux/skbuff.h:17:
   In file included from include/linux/bvec.h:10:
   In file included from include/linux/highmem.h:8:
   In file included from include/linux/cacheflush.h:5:
   In file included from arch/arm/include/asm/cacheflush.h:10:
   In file included from include/linux/mm.h:2210:
   include/linux/vmstat.h:522:36: warning: arithmetic between different enumeration types ('enum node_stat_item' and 'enum lru_list') [-Wenum-enum-conversion]
     522 |         return node_stat_name(NR_LRU_BASE + lru) + 3; // skip "nr_"
         |                               ~~~~~~~~~~~ ^ ~~~
>> net/ipv4/icmp.c:1157:16: warning: variable 'net' is uninitialized when used here [-Wuninitialized]
    1157 |         if (READ_ONCE(net->ipv4.sysctl_icmp_timestamp_ignore_all))
         |                       ^~~
   include/asm-generic/rwonce.h:50:14: note: expanded from macro 'READ_ONCE'
      50 |         __READ_ONCE(x);                                                 \
         |                     ^
   include/asm-generic/rwonce.h:44:72: note: expanded from macro '__READ_ONCE'
      44 | #define __READ_ONCE(x)  (*(const volatile __unqual_scalar_typeof(x) *)&(x))
         |                                                                         ^
   net/ipv4/icmp.c:1155:17: note: initialize the variable 'net' to silence this warning
    1155 |         struct net *net;
         |                        ^
         |                         = NULL
   2 warnings generated.


vim +/net +1157 net/ipv4/icmp.c

  1144	
  1145	/*
  1146	 *	Handle ICMP Timestamp requests.
  1147	 *	RFC 1122: 3.2.2.8 MAY implement ICMP timestamp requests.
  1148	 *		  SHOULD be in the kernel for minimum random latency.
  1149	 *		  MUST be accurate to a few minutes.
  1150	 *		  MUST be updated at least at 15Hz.
  1151	 */
  1152	static enum skb_drop_reason icmp_timestamp(struct sk_buff *skb)
  1153	{
  1154		struct icmp_bxm icmp_param;
  1155		struct net *net;
  1156	
> 1157		if (READ_ONCE(net->ipv4.sysctl_icmp_timestamp_ignore_all))
  1158			return SKB_NOT_DROPPED_YET;
  1159	
  1160		/*
  1161		 *	Too short.
  1162		 */
  1163		if (skb->len < 4)
  1164			goto out_err;
  1165	
  1166		/*
  1167		 *	Fill in the current time as ms since midnight UT:
  1168		 */
  1169		icmp_param.data.times[1] = inet_current_timestamp();
  1170		icmp_param.data.times[2] = icmp_param.data.times[1];
  1171	
  1172		BUG_ON(skb_copy_bits(skb, 0, &icmp_param.data.times[0], 4));
  1173	
  1174		icmp_param.data.icmph	   = *icmp_hdr(skb);
  1175		icmp_param.data.icmph.type = ICMP_TIMESTAMPREPLY;
  1176		icmp_param.data.icmph.code = 0;
  1177		icmp_param.skb		   = skb;
  1178		icmp_param.offset	   = 0;
  1179		icmp_param.data_len	   = 0;
  1180		icmp_param.head_len	   = sizeof(struct icmphdr) + 12;
  1181		icmp_reply(&icmp_param, skb);
  1182		return SKB_NOT_DROPPED_YET;
  1183	
  1184	out_err:
  1185		__ICMP_INC_STATS(dev_net(skb_dst(skb)->dev), ICMP_MIB_INERRORS);
  1186		return SKB_DROP_REASON_PKT_TOO_SMALL;
  1187	}
  1188	

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