CVE-2023-53450 ext4: remove a BUG_ON in ext4_mb_release_group_pa()

In the Linux kernel, the following vulnerability has been resolved: ext4: remove a BUGON in ext4mbreleasegrouppa If a malicious fuzzer overwrites the ext4 superblock while it is mounted such that the sfirstdatablock is set to a very large number, the calculation of the block group can underflow,...