f2fs: enhance sanity_check_raw_super() to avoid potential overflows
In order to avoid the below overflow issue, we should have checked the
boundaries in superblock before reaching out to allocation. As Linus suggested,
the right place should be sanity_check_raw_super().
Dr Silvio Cesare of InfoSect reported:
There are integer overflows with using the cp_payload superblock field in the
f2fs filesystem potentially leading to memory corruption.
include/linux/f2fs_fs.h
struct f2fs_super_block {
...
__le32 cp_payload;
fs/f2fs/f2fs.h
typedef u32 block_t; /*
* should not change u32, since it is the on-disk block
* address format, __le32.
*/
...