【标题描述】代码检视发现的两个问题修改
【环境信息】

uname -a

Linux qemu 5.10.0+ #37 SMP Mon Jan 16 07:55:29 UTC 2023 aarch64 aarch64 aarch64 GNU/Linux
无特殊组网，代码检视发现的问题。
【问题复现步骤】

1. 修改memcpy_mcs的返回值类型。
2. 增加memcpy_mcs的kasan检测支持。
   出现概率(是否必现，概率性错误)
   【预期结果】
   加入修改前memcpy_mcs()不支持KASAN检测
   【实际结果】
   加入修改后memcpy_mcs()支持KASAN检测，日志如下：
   ==================================================================
   BUG: KASAN: slab-out-of-bounds in sample_init+0x1c4/0x1000 [sample]
   Read of size 4196 at addr ffff0c1680eca000 by task insmod/312

CPU: 1 PID: 312 Comm: insmod Tainted: G OE 5.10.0-03309-gf9a7511163e6 #26
Hardware name: linux,dummy-virt (DT)
Call trace:
dump_backtrace+0x0/0x300
show_stack+0x20/0x30
dump_stack+0x104/0x17c
print_address_description.constprop.0+0x48/0x548
kasan_report+0x114/0x210
check_memory_region+0x100/0x1b8
memcpy_mcs+0x54/0xf0
sample_init+0x1c4/0x1000 [sample]
do_one_initcall+0xa4/0x340
do_init_module+0xd0/0x338
load_module+0x1710/0x19a0
__se_sys_finit_module+0x10c/0x198
__arm64_sys_finit_module+0x4c/0x60
el0_svc_common.constprop.0+0xb4/0x2a8
do_el0_svc+0x40/0xa8
el0_svc+0x20/0x30
el0_sync_handler+0xb0/0xb8
el0_sync+0x160/0x180

Allocated by task 312:
kasan_save_stack+0x28/0x58
__kasan_kmalloc.isra.0+0xa4/0xd0
kasan_kmalloc+0x10/0x20
kmem_cache_alloc_trace+0xe0/0x578
sample_init+0x17c/0x1000 [sample]
do_one_initcall+0xa4/0x340
do_init_module+0xd0/0x338
load_module+0x1710/0x19a0
__se_sys_finit_module+0x10c/0x198
__arm64_sys_finit_module+0x4c/0x60
el0_svc_common.constprop.0+0xb4/0x2a8
do_el0_svc+0x40/0xa8
el0_svc+0x20/0x30
el0_sync_handler+0xb0/0xb8
el0_sync+0x160/0x180

The buggy address belongs to the object at ffff0c1680eca000
which belongs to the cache kmalloc-4k of size 4096
The buggy address is located 0 bytes inside of
4096-byte region [ffff0c1680eca000, ffff0c1680ecb000)
The buggy address belongs to the page:
page:0000000028026f88 refcount:1 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x100ec8
head:0000000028026f88 order:3 compound_mapcount:0 compound_pincount:0
flags: 0x17ffff800010200(slab|head|node=0|zone=2|lastcpupid=0xfffff)
raw: 017ffff800010200 0000000000000000 dead000000000122 ffff0c1680002e00
raw: 0000000000000000 0000000080040004 00000001ffffffff 0000000000000000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
ffff0c1680ecaf00: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
ffff0c1680ecaf80: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00

ffff0c1680ecb000: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
^
ffff0c1680ecb080: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
ffff0c1680ecb100: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
==================================================================

【附件信息】
无