Re: [PATCH v1 1/1] ACPI: processor: idle: Replace strlcat() with better alternative

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

Hi Andy,

kernel test robot noticed the following build warnings:

[auto build test WARNING on rafael-pm/linux-next]
[also build test WARNING on rafael-pm/bleeding-edge linus/master v7.0-rc4 next-20260316]
[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/Andy-Shevchenko/ACPI-processor-idle-Replace-strlcat-with-better-alternative/20260317-014800
base:   https://git.kernel.org/pub/scm/linux/kernel/git/rafael/linux-pm.git linux-next
patch link:    https://lore.kernel.org/r/20260316170158.1596857-1-andriy.shevchenko%40linux.intel.com
patch subject: [PATCH v1 1/1] ACPI: processor: idle: Replace strlcat() with better alternative
config: x86_64-rhel-9.4 (https://download.01.org/0day-ci/archive/20260317/202603170957.D9ZQ5sVR-lkp@intel.com/config)
compiler: gcc-14 (Debian 14.2.0-19) 14.2.0
reproduce (this is a W=1 build): (https://download.01.org/0day-ci/archive/20260317/202603170957.D9ZQ5sVR-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/202603170957.D9ZQ5sVR-lkp@intel.com/

All warnings (new ones prefixed by >>):

   drivers/acpi/processor_idle.c: In function 'flatten_lpi_states':
>> drivers/acpi/processor_idle.c:1013:56: warning: 'snprintf' output may be truncated before the last format character [-Wformat-truncation=]
    1013 |         snprintf(result->desc, ACPI_CX_DESC_LEN, "%s+%s", local->desc, parent->desc);
         |                                                        ^
   In function 'combine_lpi_states',
       inlined from 'flatten_lpi_states' at drivers/acpi/processor_idle.c:1059:8:
   drivers/acpi/processor_idle.c:1013:9: note: 'snprintf' output 2 or more bytes (assuming 33) into a destination of size 32
    1013 |         snprintf(result->desc, ACPI_CX_DESC_LEN, "%s+%s", local->desc, parent->desc);
         |         ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~


vim +/snprintf +1013 drivers/acpi/processor_idle.c

   984	
   985	/**
   986	 * combine_lpi_states - combine local and parent LPI states to form a composite LPI state
   987	 *
   988	 * @local: local LPI state
   989	 * @parent: parent LPI state
   990	 * @result: composite LPI state
   991	 */
   992	static bool combine_lpi_states(struct acpi_lpi_state *local,
   993				       struct acpi_lpi_state *parent,
   994				       struct acpi_lpi_state *result)
   995	{
   996		if (parent->entry_method == ACPI_CSTATE_INTEGER) {
   997			if (!parent->address) /* 0 means autopromotable */
   998				return false;
   999			result->address = local->address + parent->address;
  1000		} else {
  1001			result->address = parent->address;
  1002		}
  1003	
  1004		result->min_residency = max(local->min_residency, parent->min_residency);
  1005		result->wake_latency = local->wake_latency + parent->wake_latency;
  1006		result->enable_parent_state = parent->enable_parent_state;
  1007		result->entry_method = local->entry_method;
  1008	
  1009		result->flags = parent->flags;
  1010		result->arch_flags = parent->arch_flags;
  1011		result->index = parent->index;
  1012	
> 1013		snprintf(result->desc, ACPI_CX_DESC_LEN, "%s+%s", local->desc, parent->desc);
  1014		return true;
  1015	}
  1016	

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