linux-kernel - arch/x86/kernel/callthunks.c:332:35: warning: '%lu' directive writing between 1 and 10 bytes into a region of size 7

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Date:   Sun, 29 Oct 2023 08:55:12 +0800
From:   kernel test robot <lkp@...el.com>
To:     Thomas Gleixner <tglx@...utronix.de>
Cc:     oe-kbuild-all@...ts.linux.dev, linux-kernel@...r.kernel.org,
        Peter Zijlstra <peterz@...radead.org>
Subject: arch/x86/kernel/callthunks.c:332:35: warning: '%lu' directive
 writing between 1 and 10 bytes into a region of size 7

tree:   https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git master
head:   2af9b20dbb39f6ebf9b9b6c090271594627d818e
commit: f5c1bb2afe93396d41c5cbdcb909b08a75b8dde4 x86/calldepth: Add ret/call counting for debug
date:   1 year ago
config: x86_64-randconfig-r013-20230116 (https://download.01.org/0day-ci/archive/20231029/202310290814.2Io3e73Q-lkp@intel.com/config)
compiler: gcc-12 (Debian 12.2.0-14) 12.2.0
reproduce (this is a W=1 build): (https://download.01.org/0day-ci/archive/20231029/202310290814.2Io3e73Q-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@...el.com>
| Closes: https://lore.kernel.org/oe-kbuild-all/202310290814.2Io3e73Q-lkp@intel.com/

All warnings (new ones prefixed by >>):

   arch/x86/kernel/callthunks.c: In function 'callthunks_debugfs_init':
>> arch/x86/kernel/callthunks.c:332:35: warning: '%lu' directive writing between 1 and 10 bytes into a region of size 7 [-Wformat-overflow=]
     332 |                 sprintf(name, "cpu%lu", cpu);
         |                                   ^~~
   arch/x86/kernel/callthunks.c:332:31: note: directive argument in the range [0, 4294967294]
     332 |                 sprintf(name, "cpu%lu", cpu);
         |                               ^~~~~~~~
   arch/x86/kernel/callthunks.c:332:17: note: 'sprintf' output between 5 and 14 bytes into a destination of size 10
     332 |                 sprintf(name, "cpu%lu", cpu);
         |                 ^~~~~~~~~~~~~~~~~~~~~~~~~~~~


vim +332 arch/x86/kernel/callthunks.c

   321	
   322	static int __init callthunks_debugfs_init(void)
   323	{
   324		struct dentry *dir;
   325		unsigned long cpu;
   326	
   327		dir = debugfs_create_dir("callthunks", NULL);
   328		for_each_possible_cpu(cpu) {
   329			void *arg = (void *)cpu;
   330			char name [10];
   331	
 > 332			sprintf(name, "cpu%lu", cpu);

-- 
0-DAY CI Kernel Test Service
https://github.com/intel/lkp-tests/wiki