arch/x86/kernel/cpu/mce/dev-mcelog.c:346:2: warning: 'strncpy' output truncated before terminating nul copying 12 bytes from a string of the same length

[kbuild test robot]

tree:   https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git 
master
head:   444fc5cde64330661bf59944c43844e7d4c2ccd8
commit: d8ecca4043f2d9d89daab7915eca8c2ec6254d0f x86/mce/dev-mcelog: 
Dynamically allocate space for machine check records
date:   3 months ago
config: x86_64-lkp (attached as .config)
compiler: gcc-9 (Debian 9.3.0-13) 9.3.0
reproduce (this is a W=1 build):
        git checkout d8ecca4043f2d9d89daab7915eca8c2ec6254d0f
        # save the attached .config to linux build tree
        make W=1 ARCH=x86_64 

If you fix the issue, kindly add following tag as appropriate
Reported-by: kbuild test robot <l...@intel.com>

All warnings (new ones prefixed by >>, old ones prefixed by <<):

arch/x86/kernel/cpu/mce/dev-mcelog.c: In function 'dev_mcelog_init_device':
>> arch/x86/kernel/cpu/mce/dev-mcelog.c:346:2: warning: 'strncpy' output 
>> truncated before terminating nul copying 12 bytes from a string of the same 
>> length [-Wstringop-truncation]
346 |  strncpy(mcelog->signature, MCE_LOG_SIGNATURE, sizeof(mcelog->signature));
|  ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

vim +/strncpy +346 arch/x86/kernel/cpu/mce/dev-mcelog.c

   335  
   336  static __init int dev_mcelog_init_device(void)
   337  {
   338          int mce_log_len;
   339          int err;
   340  
   341          mce_log_len = max(MCE_LOG_MIN_LEN, num_online_cpus());
   342          mcelog = kzalloc(sizeof(*mcelog) + mce_log_len * sizeof(struct 
mce), GFP_KERNEL);
   343          if (!mcelog)
   344                  return -ENOMEM;
   345  
 > 346          strncpy(mcelog->signature, MCE_LOG_SIGNATURE, 
 > sizeof(mcelog->signature));

---
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.config.gz
Description: application/gzip