Re: [PATCH v7 3/4] treewide: Replace 'get_task_comm()' with 'strscpy_pad()'

[Bhupesh Sharma <bhsharma@igalia.com>]

Hi,

On 8/11/25 4:55 PM, kernel test robot wrote:
> Hi Bhupesh,
>
> kernel test robot noticed the following build errors:
>
> [auto build test ERROR on next-20250808]
> [cannot apply to trace/for-next tip/sched/core brauner-vfs/vfs.all linus/master v6.17-rc1 v6.16 v6.16-rc7 v6.17-rc1]
> [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/Bhupesh/exec-Remove-obsolete-comments/20250811-144920
> base:   next-20250808
> patch link:    https://lore.kernel.org/r/20250811064609.918593-4-bhupesh%40igalia.com
> patch subject: [PATCH v7 3/4] treewide: Replace 'get_task_comm()' with 'strscpy_pad()'
> config: sh-randconfig-002-20250811 (https://download.01.org/0day-ci/archive/20250811/202508111835.JFL8DgKY-lkp@intel.com/config)
> compiler: sh4-linux-gcc (GCC) 15.1.0
> reproduce (this is a W=1 build): (https://download.01.org/0day-ci/archive/20250811/202508111835.JFL8DgKY-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/202508111835.JFL8DgKY-lkp@intel.com/
>
> All errors (new ones prefixed by >>):
>
>     In file included from include/linux/bitmap.h:13,
>                      from include/linux/cpumask.h:12,
>                      from include/linux/smp.h:13,
>                      from include/linux/lockdep.h:14,
>                      from include/linux/spinlock.h:63,
>                      from include/linux/mmzone.h:8,
>                      from include/linux/gfp.h:7,
>                      from include/linux/umh.h:4,
>                      from include/linux/kmod.h:9,
>                      from include/linux/module.h:18,
>                      from net/netfilter/nf_tables_api.c:8:
>     net/netfilter/nf_tables_api.c: In function 'nf_tables_fill_gen_info':
>>> include/linux/string.h:116:50: error: passing argument 3 of 'nla_put_string' makes pointer from integer without a cast [-Wint-conversion]
>       116 | #define sized_strscpy_pad(dest, src, count)     ({                      \
>           |                                                 ~^~~~~~~~~~~~~~~~~~~~~~~~
>           |                                                  |
>           |                                                  ssize_t {aka int}
>       117 |         char *__dst = (dest);                                           \
>           |         ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
>       118 |         const char *__src = (src);                                      \
>           |         ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
>       119 |         const size_t __count = (count);                                 \
>           |         ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
>       120 |         ssize_t __wrote;                                                \
>           |         ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
>       121 |                                                                         \
>           |                                                                         ~
>       122 |         __wrote = sized_strscpy(__dst, __src, __count);                 \
>           |         ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
>       123 |         if (__wrote >= 0 && __wrote < __count)                          \
>           |         ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
>       124 |                 memset(__dst + __wrote + 1, 0, __count - __wrote - 1);  \
>           |                 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
>       125 |         __wrote;                                                        \
>           |         ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
>       126 | })
>           | ~~
>     include/linux/string.h:86:9: note: in expansion of macro 'sized_strscpy_pad'
>        86 |         sized_strscpy_pad(dst, src, sizeof(dst) + __must_be_array(dst) +        \
>           |         ^~~~~~~~~~~~~~~~~
>     include/linux/args.h:25:24: note: in expansion of macro '__strscpy_pad0'
>        25 | #define __CONCAT(a, b) a ## b
>           |                        ^
>     include/linux/args.h:26:27: note: in expansion of macro '__CONCAT'
>        26 | #define CONCATENATE(a, b) __CONCAT(a, b)
>           |                           ^~~~~~~~
>     include/linux/string.h:149:9: note: in expansion of macro 'CONCATENATE'
>       149 |         CONCATENATE(__strscpy_pad, COUNT_ARGS(__VA_ARGS__))(dst, src, __VA_ARGS__)
>           |         ^~~~~~~~~~~
>     net/netfilter/nf_tables_api.c:9661:53: note: in expansion of macro 'strscpy_pad'
>      9661 |             nla_put_string(skb, NFTA_GEN_PROC_NAME, strscpy_pad(buf, current->comm)))
>           |                                                     ^~~~~~~~~~~
>     In file included from include/linux/netfilter/nfnetlink.h:7,
>                      from net/netfilter/nf_tables_api.c:17:
>     include/net/netlink.h:1655:46: note: expected 'const char *' but argument is of type 'ssize_t' {aka 'int'}
>      1655 |                                  const char *str)
>           |                                  ~~~~~~~~~~~~^~~
>
>
> vim +/nla_put_string +116 include/linux/string.h
>
> e6584c3964f2ff Kees Cook        2023-09-20   74
> e6584c3964f2ff Kees Cook        2023-09-20   75  /*
> e6584c3964f2ff Kees Cook        2023-09-20   76   * The 2 argument style can only be used when dst is an array with a
> e6584c3964f2ff Kees Cook        2023-09-20   77   * known size.
> e6584c3964f2ff Kees Cook        2023-09-20   78   */
> e6584c3964f2ff Kees Cook        2023-09-20   79  #define __strscpy0(dst, src, ...)	\
> 559048d156ff33 Kees Cook        2024-08-05   80  	sized_strscpy(dst, src, sizeof(dst) + __must_be_array(dst) +	\
> 559048d156ff33 Kees Cook        2024-08-05   81  				__must_be_cstr(dst) + __must_be_cstr(src))
> 559048d156ff33 Kees Cook        2024-08-05   82  #define __strscpy1(dst, src, size)	\
> 559048d156ff33 Kees Cook        2024-08-05   83  	sized_strscpy(dst, src, size + __must_be_cstr(dst) + __must_be_cstr(src))
> e6584c3964f2ff Kees Cook        2023-09-20   84
> 8366d124ec937c Kees Cook        2024-02-02   85  #define __strscpy_pad0(dst, src, ...)	\
> 559048d156ff33 Kees Cook        2024-08-05   86  	sized_strscpy_pad(dst, src, sizeof(dst) + __must_be_array(dst) +	\
> 559048d156ff33 Kees Cook        2024-08-05   87  				    __must_be_cstr(dst) + __must_be_cstr(src))
> 559048d156ff33 Kees Cook        2024-08-05   88  #define __strscpy_pad1(dst, src, size)	\
> 559048d156ff33 Kees Cook        2024-08-05   89  	sized_strscpy_pad(dst, src, size + __must_be_cstr(dst) + __must_be_cstr(src))
> 458a3bf82df4fe Tobin C. Harding 2019-04-05   90
> e6584c3964f2ff Kees Cook        2023-09-20   91  /**
> e6584c3964f2ff Kees Cook        2023-09-20   92   * strscpy - Copy a C-string into a sized buffer
> e6584c3964f2ff Kees Cook        2023-09-20   93   * @dst: Where to copy the string to
> e6584c3964f2ff Kees Cook        2023-09-20   94   * @src: Where to copy the string from
> e6584c3964f2ff Kees Cook        2023-09-20   95   * @...: Size of destination buffer (optional)
> e6584c3964f2ff Kees Cook        2023-09-20   96   *
> e6584c3964f2ff Kees Cook        2023-09-20   97   * Copy the source string @src, or as much of it as fits, into the
> e6584c3964f2ff Kees Cook        2023-09-20   98   * destination @dst buffer. The behavior is undefined if the string
> e6584c3964f2ff Kees Cook        2023-09-20   99   * buffers overlap. The destination @dst buffer is always NUL terminated,
> e6584c3964f2ff Kees Cook        2023-09-20  100   * unless it's zero-sized.
> e6584c3964f2ff Kees Cook        2023-09-20  101   *
> e6584c3964f2ff Kees Cook        2023-09-20  102   * The size argument @... is only required when @dst is not an array, or
> e6584c3964f2ff Kees Cook        2023-09-20  103   * when the copy needs to be smaller than sizeof(@dst).
> e6584c3964f2ff Kees Cook        2023-09-20  104   *
> e6584c3964f2ff Kees Cook        2023-09-20  105   * Preferred to strncpy() since it always returns a valid string, and
> e6584c3964f2ff Kees Cook        2023-09-20  106   * doesn't unnecessarily force the tail of the destination buffer to be
> e6584c3964f2ff Kees Cook        2023-09-20  107   * zero padded. If padding is desired please use strscpy_pad().
> e6584c3964f2ff Kees Cook        2023-09-20  108   *
> e6584c3964f2ff Kees Cook        2023-09-20  109   * Returns the number of characters copied in @dst (not including the
> e6584c3964f2ff Kees Cook        2023-09-20  110   * trailing %NUL) or -E2BIG if @size is 0 or the copy from @src was
> e6584c3964f2ff Kees Cook        2023-09-20  111   * truncated.
> e6584c3964f2ff Kees Cook        2023-09-20  112   */
> e6584c3964f2ff Kees Cook        2023-09-20  113  #define strscpy(dst, src, ...)	\
> e6584c3964f2ff Kees Cook        2023-09-20  114  	CONCATENATE(__strscpy, COUNT_ARGS(__VA_ARGS__))(dst, src, __VA_ARGS__)
> 458a3bf82df4fe Tobin C. Harding 2019-04-05  115
> 8366d124ec937c Kees Cook        2024-02-02 @116  #define sized_strscpy_pad(dest, src, count)	({			\
> 8366d124ec937c Kees Cook        2024-02-02  117  	char *__dst = (dest);						\
> 8366d124ec937c Kees Cook        2024-02-02  118  	const char *__src = (src);					\
> 8366d124ec937c Kees Cook        2024-02-02  119  	const size_t __count = (count);					\
> 8366d124ec937c Kees Cook        2024-02-02  120  	ssize_t __wrote;						\
> 8366d124ec937c Kees Cook        2024-02-02  121  									\
> 8366d124ec937c Kees Cook        2024-02-02  122  	__wrote = sized_strscpy(__dst, __src, __count);			\
> 8366d124ec937c Kees Cook        2024-02-02  123  	if (__wrote >= 0 && __wrote < __count)				\
> 8366d124ec937c Kees Cook        2024-02-02  124  		memset(__dst + __wrote + 1, 0, __count - __wrote - 1);	\
> 8366d124ec937c Kees Cook        2024-02-02  125  	__wrote;							\
> 8366d124ec937c Kees Cook        2024-02-02  126  })
> 8366d124ec937c Kees Cook        2024-02-02  127
>

As mentioned in the accompanying cover letter, this patchset is based on 
'linux-next/master' (the exact sha-id used for rebase is: 
b1549501188cc9eba732c25b033df7a53ccc341f ).

Thanks,
Bhupesh