md/raid10: fix slab-out-of-bounds in md_bitmap_get_counter

hulk inclusion
category: bugfix
bugzilla: 188270, https://gitee.com/openeuler/kernel/issues/I6ECES
CVE: NA

--------------------------------

There is a bug if we write a large number to md/bitmap_set_bits.
md_bitmap_checkpage() returned -EINVAL if "page >= bitmap->pages", but the
return value was not checked immediately in md_bitmap_get_counter() in
order to set *blocks value. fix it by checking page before operate
bitmap.
Signed-off-by: NLi Nan <linan122@huawei.com>
Reviewed-by: NHou Tao <houtao1@huawei.com>
Signed-off-by: NJialin Zhang <zhangjialin11@huawei.com>

drivers/md/md-bitmap.c

@@ -1365,6 +1365,9 @@ __acquires(bitmap->lock)
 	sector_t csize;
 	int err;
 
+	if (page >= bitmap->pages)
+		return NULL;
+
 	err = md_bitmap_checkpage(bitmap, page, create, 0);
 
 	if (bitmap->bp[page].hijacked ||