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

From: kernel test robot
Date: Sat Jan 06 2024 - 20:39:53 EST


Hi Thomas,

FYI, the error/warning still remains.

tree: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git master
head: 52b1853b080a082ec3749c3a9577f6c71b1d4a90
commit: f5c1bb2afe93396d41c5cbdcb909b08a75b8dde4 x86/calldepth: Add ret/call counting for debug
date: 1 year, 3 months ago
config: x86_64-randconfig-r052-20240106 (https://download.01.org/0day-ci/archive/20240107/202401070957.QH0oQjgO-lkp@xxxxxxxxx/config)
compiler: gcc-11 (Debian 11.3.0-12) 11.3.0
reproduce (this is a W=1 build): (https://download.01.org/0day-ci/archive/20240107/202401070957.QH0oQjgO-lkp@xxxxxxxxx/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@xxxxxxxxx>
| Closes: https://lore.kernel.org/oe-kbuild-all/202401070957.QH0oQjgO-lkp@xxxxxxxxx/

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);

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