Re: [PATCH 3/3] s390/vfio-ap: Add write support to sysfs attr ap_config

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

Hi Jason,

kernel test robot noticed the following build warnings:

[auto build test WARNING on kvms390/next]
[cannot apply to s390/features linus/master v6.8-rc1 next-20240125]
[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/Jason-J-Herne/s390-ap-Externalize-AP-bus-specific-bitmap-reading-function/20240126-223952
base:   https://git.kernel.org/pub/scm/linux/kernel/git/kvms390/linux.git next
patch link:    https://lore.kernel.org/r/20240126143533.14043-4-jjherne%40linux.ibm.com
patch subject: [PATCH 3/3] s390/vfio-ap: Add write support to sysfs attr ap_config
config: s390-defconfig (https://download.01.org/0day-ci/archive/20240128/202401282141.A8V47yFI-lkp@intel.com/config)
compiler: s390-linux-gcc (GCC) 13.2.0
reproduce (this is a W=1 build): (https://download.01.org/0day-ci/archive/20240128/202401282141.A8V47yFI-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/202401282141.A8V47yFI-lkp@intel.com/

All warnings (new ones prefixed by >>):

   In file included 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/mm.h:7,
                    from include/linux/scatterlist.h:8,
                    from include/linux/iommu.h:10,
                    from include/linux/vfio.h:12,
                    from drivers/s390/crypto/vfio_ap_ops.c:12:
   In function 'bitmap_copy',
       inlined from 'ap_matrix_copy' at drivers/s390/crypto/vfio_ap_ops.c:1593:2,
       inlined from 'ap_config_store' at drivers/s390/crypto/vfio_ap_ops.c:1616:2:
>> include/linux/bitmap.h:245:17: warning: 'memcpy' reading 32 bytes from a region of size 0 [-Wstringop-overread]
     245 |                 memcpy(dst, src, len);
         |                 ^~~~~~~~~~~~~~~~~~~~~
   In function 'ap_config_store':
   cc1: note: source object is likely at address zero
   In function 'bitmap_copy',
       inlined from 'ap_matrix_copy' at drivers/s390/crypto/vfio_ap_ops.c:1594:2,
       inlined from 'ap_config_store' at drivers/s390/crypto/vfio_ap_ops.c:1616:2:
>> include/linux/bitmap.h:245:17: warning: 'memcpy' reading 32 bytes from a region of size 0 [-Wstringop-overread]
     245 |                 memcpy(dst, src, len);
         |                 ^~~~~~~~~~~~~~~~~~~~~
   In function 'ap_config_store':
   cc1: note: source object is likely at address zero
   In function 'bitmap_copy',
       inlined from 'ap_matrix_copy' at drivers/s390/crypto/vfio_ap_ops.c:1595:2,
       inlined from 'ap_config_store' at drivers/s390/crypto/vfio_ap_ops.c:1616:2:
>> include/linux/bitmap.h:245:17: warning: 'memcpy' reading 32 bytes from a region of size 0 [-Wstringop-overread]
     245 |                 memcpy(dst, src, len);
         |                 ^~~~~~~~~~~~~~~~~~~~~
   In function 'ap_config_store':
   cc1: note: source object is likely at address zero


vim +/memcpy +245 include/linux/bitmap.h

^1da177e4c3f41 Linus Torvalds    2005-04-16  236  
^1da177e4c3f41 Linus Torvalds    2005-04-16  237  static inline void bitmap_copy(unsigned long *dst, const unsigned long *src,
8b4daad52fee77 Rasmus Villemoes  2015-02-12  238  			unsigned int nbits)
^1da177e4c3f41 Linus Torvalds    2005-04-16  239  {
8b4daad52fee77 Rasmus Villemoes  2015-02-12  240  	unsigned int len = BITS_TO_LONGS(nbits) * sizeof(unsigned long);
3e7e5baaaba780 Alexander Lobakin 2022-06-24  241  
3e7e5baaaba780 Alexander Lobakin 2022-06-24  242  	if (small_const_nbits(nbits))
3e7e5baaaba780 Alexander Lobakin 2022-06-24  243  		*dst = *src;
3e7e5baaaba780 Alexander Lobakin 2022-06-24  244  	else
^1da177e4c3f41 Linus Torvalds    2005-04-16 @245  		memcpy(dst, src, len);
^1da177e4c3f41 Linus Torvalds    2005-04-16  246  }
^1da177e4c3f41 Linus Torvalds    2005-04-16  247  

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