linux-kernel - Re: drivers/clk/clk-renesas-pcie.c:178:31: warning: '%d' directive output may be truncated writing between 1 and 4 bytes into a region of size 2

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Message-ID: <55f6f8ec-48bf-4d0e-ab74-b5bc7c9a7f56@mailbox.org>
Date: Mon, 20 Jan 2025 08:19:20 +0100
From: Marek Vasut <marek.vasut@...lbox.org>
To: kernel test robot <lkp@...el.com>,
 Marek Vasut <marek.vasut+renesas@...lbox.org>
Cc: oe-kbuild-all@...ts.linux.dev, linux-kernel@...r.kernel.org,
 Stephen Boyd <sboyd@...nel.org>
Subject: Re: drivers/clk/clk-renesas-pcie.c:178:31: warning: '%d' directive
 output may be truncated writing between 1 and 4 bytes into a region of size 2

On 1/20/25 12:45 AM, kernel test robot wrote:
> tree:   https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git master
> head:   9528d418de4d83c7ada69314ddd8d4427b1f703a
> commit: cd9a5c97dfdaeb9c8ac02e14d7ccbd445e8b5265 clk: rs9: Replace model check with bitshift from chip data
> date:   1 year, 1 month ago
> config: s390-randconfig-r111-20250120 (https://download.01.org/0day-ci/archive/20250120/202501200756.HycDH8wZ-lkp@intel.com/config)
> compiler: s390-linux-gcc (GCC) 14.2.0
> reproduce: (https://download.01.org/0day-ci/archive/20250120/202501200756.HycDH8wZ-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/202501200756.HycDH8wZ-lkp@intel.com/
> 
> All warnings (new ones prefixed by >>):
> 
>     drivers/clk/clk-renesas-pcie.c: In function 'rs9_probe':
>>> drivers/clk/clk-renesas-pcie.c:178:31: warning: '%d' directive output may be truncated writing between 1 and 4 bytes into a region of size 2 [-Wformat-truncation=]
>       178 |         snprintf(name, 5, "DIF%d", idx);
>           |                               ^~
>     In function 'rs9_get_output_config',
>         inlined from 'rs9_probe' at drivers/clk/clk-renesas-pcie.c:305:9:
>     drivers/clk/clk-renesas-pcie.c:178:27: note: directive argument in the range [-250, 63]
>       178 |         snprintf(name, 5, "DIF%d", idx);
>           |                           ^~~~~~~
>     drivers/clk/clk-renesas-pcie.c:178:9: note: 'snprintf' output between 5 and 8 bytes into a destination of size 5
>       178 |         snprintf(name, 5, "DIF%d", idx);
>           |         ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
> 
I can extend the name variable to length 8 to mitigate this warning, but 
there is some 8 DIF outputs maximum on this hardware, so it is known 
this %d field would not be longer than 1 decimal number. Shall I send 
such a patch ?