The fix to the mentioned MDEV (checksum calculation for row compression + encryption introduced a bug noticed by both me and anikitin.

Andrii Nikitin added a comment - Yesterday

For me current mtr test xb_compressed_encrypted.test is still crashing occasionally with stack below:

xtrabackup.exe!mach_read_from_4()[mach0data.ic:186]

xtrabackup.exe!fil_space_verify_crypt_checksum()[fil0crypt.cc:955]

xtrabackup.exe!xb_fil_cur_read()[fil_cur.cc:349]

xtrabackup.exe!xtrabackup_copy_datafile()[xtrabackup.cc:2418]

xtrabackup.exe!data_copy_thread_func()[xtrabackup.cc:2934]

It appears in debugger that memory passed to mach_read_from_4 above is either corrupted or garbage

wlad Vladislav Vaintroub added a comment - 2 minutes ago

I had this, too.
The immediate reason seem to be that fil_space_verify_crypt_checksum() expects a page of the size UNIV_PAGE_SIZE, 16K
And it checks the checksum at the end of this 16K

However, the passed page had (from xtrabackup POV) page size of 8K , and also zip_size ok 8K.
That page was the last one, the end of allocated region, thus attempt to read 8K past allocated region crashed.