mainline build failure due to 0a97953fd221 ("lib: add bitmap_{from,to}_arr64")

[Sudip Mukherjee]

Hi All,

The latest mainline kernel branch fails to build for "arm allmodconfig"
and "csky allmodconfig".

"arm allmodconfig" fails with the error:

In file included from ./include/linux/string.h:253,
                 from ./include/linux/bitmap.h:11,
                 from ./include/linux/cpumask.h:12,
                 from ./include/linux/smp.h:13,
                 from ./include/linux/lockdep.h:14,
                 from ./include/linux/mutex.h:17,
                 from ./include/linux/rfkill.h:35,
                 from net/bluetooth/hci_core.c:29:
In function 'fortify_memcpy_chk',
    inlined from 'bitmap_copy' at ./include/linux/bitmap.h:254:2,
    inlined from 'bitmap_copy_clear_tail' at ./include/linux/bitmap.h:263:2,
    inlined from 'bitmap_from_u64' at ./include/linux/bitmap.h:540:2,
    inlined from 'hci_bdaddr_list_add_with_flags' at net/bluetooth/hci_core.c:2156:2:
./include/linux/fortify-string.h:344:25: error: call to '__write_overflow_field' declared with attribute warning: detected write beyond size of field (1st parameter); maybe use struct_group()? [-Werror=attribute-warning]
  344 |                         __write_overflow_field(p_size_field, size);


And, "csky allmodconfig" fails with the error:

In file included from ./include/linux/cpumask.h:12,
                 from ./include/linux/mm_types_task.h:14,
                 from ./include/linux/mm_types.h:5,
                 from ./include/linux/buildid.h:5,
                 from ./include/linux/module.h:14,
                 from net/bluetooth/mgmt.c:27:
In function 'bitmap_copy',
    inlined from 'bitmap_copy_clear_tail' at ./include/linux/bitmap.h:263:2,
    inlined from 'bitmap_from_u64' at ./include/linux/bitmap.h:540:2,
    inlined from 'set_device_flags' at net/bluetooth/mgmt.c:4534:4:
./include/linux/bitmap.h:254:9: error: 'memcpy' forming offset [4, 7] is out of the bounds [0, 4] of object 'flags' with type 'long unsigned int[1]' [-Werror=array-bounds]
  254 |         memcpy(dst, src, len);
      |         ^~~~~~~~~~~~~~~~~~~~~
In file included from ./include/linux/kasan-checks.h:5,
                 from ./include/asm-generic/rwonce.h:26,
                 from ./arch/csky/include/generated/asm/rwonce.h:1,
                 from ./include/linux/compiler.h:248,
                 from ./include/linux/build_bug.h:5,
                 from ./include/linux/container_of.h:5,
                 from ./include/linux/list.h:5,
                 from ./include/linux/module.h:12,
                 from net/bluetooth/mgmt.c:27:
net/bluetooth/mgmt.c: In function 'set_device_flags':
net/bluetooth/mgmt.c:4532:40: note: 'flags' declared here
 4532 |                         DECLARE_BITMAP(flags, __HCI_CONN_NUM_FLAGS);
      |                                        ^~~~~
./include/linux/types.h:11:23: note: in definition of macro 'DECLARE_BITMAP'
   11 |         unsigned long name[BITS_TO_LONGS(bits)]


For both the failures, git bisect points to:
0a97953fd221 ("lib: add bitmap_{from,to}_arr64")


And, reverting it on top of mainline branch has fixed both the build failures.


--
Regards
Sudip