linux-kernel - drivers/gpu/drm/nouveau/nouveau_backlight.c:54:69: warning: '%d' directive output may be truncated writing between 1 and 10 bytes into a region of size 3

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Message-ID: <202312050324.0kv4PnfZ-lkp@intel.com>
Date:   Tue, 5 Dec 2023 03:40:06 +0800
From:   kernel test robot <lkp@...el.com>
To:     Christophe JAILLET <christophe.jaillet@...adoo.fr>
Cc:     oe-kbuild-all@...ts.linux.dev, linux-kernel@...r.kernel.org,
        Lyude Paul <lyude@...hat.com>
Subject: drivers/gpu/drm/nouveau/nouveau_backlight.c:54:69: warning: '%d'
 directive output may be truncated writing between 1 and 10 bytes into a
 region of size 3

tree:   https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git master
head:   33cc938e65a98f1d29d0a18403dbbee050dcad9a
commit: ab244be47a8f111bc82496a8a20c907236e37f95 drm/nouveau: Fix a potential theorical leak in nouveau_get_backlight_name()
date:   1 year, 7 months ago
config: x86_64-buildonly-randconfig-005-20230918 (https://download.01.org/0day-ci/archive/20231205/202312050324.0kv4PnfZ-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/20231205/202312050324.0kv4PnfZ-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/202312050324.0kv4PnfZ-lkp@intel.com/

All warnings (new ones prefixed by >>):

   drivers/gpu/drm/nouveau/nouveau_backlight.c: In function 'nouveau_backlight_init':
>> drivers/gpu/drm/nouveau/nouveau_backlight.c:54:69: warning: '%d' directive output may be truncated writing between 1 and 10 bytes into a region of size 3 [-Wformat-truncation=]
      54 |                 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:408:7:
   drivers/gpu/drm/nouveau/nouveau_backlight.c:54:56: note: directive argument in the range [1, 2147483647]
      54 |                 snprintf(backlight_name, BL_NAME_SIZE, "nv_backlight%d", nb);
         |                                                        ^~~~~~~~~~~~~~~~
   drivers/gpu/drm/nouveau/nouveau_backlight.c:54:17: note: 'snprintf' output between 14 and 23 bytes into a destination of size 15
      54 |                 snprintf(backlight_name, BL_NAME_SIZE, "nv_backlight%d", nb);
         |                 ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~


vim +54 drivers/gpu/drm/nouveau/nouveau_backlight.c

db1a0ae21461af Pierre Moreau      2016-12-08  44  
db1a0ae21461af Pierre Moreau      2016-12-08  45  static bool
6d757753cef8d5 Lyude Paul         2018-09-06  46  nouveau_get_backlight_name(char backlight_name[BL_NAME_SIZE],
6d757753cef8d5 Lyude Paul         2018-09-06  47  			   struct nouveau_backlight *bl)
db1a0ae21461af Pierre Moreau      2016-12-08  48  {
ab244be47a8f11 Christophe JAILLET 2022-02-09  49  	const int nb = ida_alloc_max(&bl_ida, 99, GFP_KERNEL);
ab244be47a8f11 Christophe JAILLET 2022-02-09  50  
ab244be47a8f11 Christophe JAILLET 2022-02-09  51  	if (nb < 0)
db1a0ae21461af Pierre Moreau      2016-12-08  52  		return false;
db1a0ae21461af Pierre Moreau      2016-12-08  53  	if (nb > 0)
db1a0ae21461af Pierre Moreau      2016-12-08 @54  		snprintf(backlight_name, BL_NAME_SIZE, "nv_backlight%d", nb);
db1a0ae21461af Pierre Moreau      2016-12-08  55  	else
db1a0ae21461af Pierre Moreau      2016-12-08  56  		snprintf(backlight_name, BL_NAME_SIZE, "nv_backlight");
6d757753cef8d5 Lyude Paul         2018-09-06  57  	bl->id = nb;
db1a0ae21461af Pierre Moreau      2016-12-08  58  	return true;
db1a0ae21461af Pierre Moreau      2016-12-08  59  }
db1a0ae21461af Pierre Moreau      2016-12-08  60  

:::::: The code at line 54 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