linux-kernel - drivers/gpu/drm/nouveau/nouveau_backlight.c:56:69: error: '%d' directive output may be truncated writing between 1 and 10 bytes into a region of size 3

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Message-ID: <202501022122.Pct9ERae-lkp@intel.com>
Date: Thu, 2 Jan 2025 21:14:13 +0800
From: kernel test robot <lkp@...el.com>
To: Jani Nikula <jani.nikula@...el.com>
Cc: oe-kbuild-all@...ts.linux.dev, linux-kernel@...r.kernel.org,
	Hamza Mahfooz <hamza.mahfooz@....com>,
	Javier Martinez Canillas <javierm@...hat.com>
Subject: drivers/gpu/drm/nouveau/nouveau_backlight.c:56:69: error: '%d'
 directive output may be truncated writing between 1 and 10 bytes into a
 region of size 3

Hi Jani,

FYI, the error/warning still remains.

tree:   https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git master
head:   56e6a3499e14716b9a28a307bb6d18c10e95301e
commit: f89632a9e5fa6c4787c14458cd42a9ef42025434 drm: Add CONFIG_DRM_WERROR
date:   10 months ago
config: loongarch-randconfig-002-20250102 (https://download.01.org/0day-ci/archive/20250102/202501022122.Pct9ERae-lkp@intel.com/config)
compiler: loongarch64-linux-gcc (GCC) 14.2.0
reproduce (this is a W=1 build): (https://download.01.org/0day-ci/archive/20250102/202501022122.Pct9ERae-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/202501022122.Pct9ERae-lkp@intel.com/

All errors (new ones prefixed by >>):

   drivers/gpu/drm/nouveau/nouveau_backlight.c: In function 'nouveau_backlight_init':
>> drivers/gpu/drm/nouveau/nouveau_backlight.c:56:69: error: '%d' directive output may be truncated writing between 1 and 10 bytes into a region of size 3 [-Werror=format-truncation=]
      56 |                 snprintf(backlight_name, BL_NAME_SIZE, "nv_backlight%d", nb);
         |                                                                     ^~
   In function 'nouveau_get_backlight_name',
       inlined from 'nouveau_backlight_init' at drivers/gpu/drm/nouveau/nouveau_backlight.c:351:7:
   drivers/gpu/drm/nouveau/nouveau_backlight.c:56:56: note: directive argument in the range [1, 2147483647]
      56 |                 snprintf(backlight_name, BL_NAME_SIZE, "nv_backlight%d", nb);
         |                                                        ^~~~~~~~~~~~~~~~
   drivers/gpu/drm/nouveau/nouveau_backlight.c:56:17: note: 'snprintf' output between 14 and 23 bytes into a destination of size 15
      56 |                 snprintf(backlight_name, BL_NAME_SIZE, "nv_backlight%d", nb);
         |                 ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
   cc1: all warnings being treated as errors


vim +56 drivers/gpu/drm/nouveau/nouveau_backlight.c

db1a0ae21461af Pierre Moreau      2016-12-08  46  
db1a0ae21461af Pierre Moreau      2016-12-08  47  static bool
6d757753cef8d5 Lyude Paul         2018-09-06  48  nouveau_get_backlight_name(char backlight_name[BL_NAME_SIZE],
6d757753cef8d5 Lyude Paul         2018-09-06  49  			   struct nouveau_backlight *bl)
db1a0ae21461af Pierre Moreau      2016-12-08  50  {
ab244be47a8f11 Christophe JAILLET 2022-02-09  51  	const int nb = ida_alloc_max(&bl_ida, 99, GFP_KERNEL);
ab244be47a8f11 Christophe JAILLET 2022-02-09  52  
ab244be47a8f11 Christophe JAILLET 2022-02-09  53  	if (nb < 0)
db1a0ae21461af Pierre Moreau      2016-12-08  54  		return false;
db1a0ae21461af Pierre Moreau      2016-12-08  55  	if (nb > 0)
db1a0ae21461af Pierre Moreau      2016-12-08 @56  		snprintf(backlight_name, BL_NAME_SIZE, "nv_backlight%d", nb);
db1a0ae21461af Pierre Moreau      2016-12-08  57  	else
db1a0ae21461af Pierre Moreau      2016-12-08  58  		snprintf(backlight_name, BL_NAME_SIZE, "nv_backlight");
6d757753cef8d5 Lyude Paul         2018-09-06  59  	bl->id = nb;
db1a0ae21461af Pierre Moreau      2016-12-08  60  	return true;
db1a0ae21461af Pierre Moreau      2016-12-08  61  }
db1a0ae21461af Pierre Moreau      2016-12-08  62  

:::::: The code at line 56 was first introduced by commit
:::::: db1a0ae21461afa4bc435651a6dd55e0e6ef4a8b drm/nouveau/bl: Assign different names to interfaces

:::::: TO: Pierre Moreau <pierre.morrow@...e.fr>
:::::: CC: Ben Skeggs <bskeggs@...hat.com>

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