MDEV-30732 : UBSAN: null pointer passed as argument 2, which is decla…

[janlindstrom]

…red to never be null in storage/innobase/handler/ha_innodb.cc

• The Jira issue number for this PR is: MDEV-30732

Description

Problem was that row_mysql_read_blob_ref can return NULL in case when blob datatype is used in a key and its real value is NULL. This NULL pointer is then used in memcpy function in wsrep_store_key_val_for_row. However,
memcpy is defined so that argument 2 must not be NULL.

Fixed by adding conditions before memcpy functions so that argument 2 is always non NULL.

Release Notes

TODO: What should the release notes say about this change?
Include any changed system variables, status variables or behaviour. Optionally list any https://mariadb.com/kb/ pages that need changing.

How can this PR be tested?

TODO: modify the automated test suite to verify that the PR causes MariaDB to behave as intended.
Consult the documentation on "Writing good test cases".

If the changes are not amenable to automated testing, please explain why not and carefully describe how to test manually.

Basing the PR against the correct MariaDB version

• This is a new feature and the PR is based against the latest MariaDB development branch.
• [ x] This is a bug fix and the PR is based against the earliest maintained branch in which the bug can be reproduced.

PR quality check

• [ x] I checked the CODING_STANDARDS.md file and my PR conforms to this where appropriate.
• [ x] For any trivial modifications to the PR, I am ok with the reviewer making the changes themselves.

[anson1014]

Minor nits:

• some unnecessary whitespace
• consider removing the brackets for your single line if statements in order to adhere to: https://github.com/MariaDB/server/blob/11.5/CODING_STANDARDS.md

Otherwise, the logic and the motivation for this change looks good to me.