MDEV-30732 : wsrep_store_key_val_for_row() may invoke memcpy() on nullptr

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.

Author: janlindstrom

mysql-test/suite/galera/r/MDEV-30732.result

@@ -0,0 +1,133 @@
+connection node_2;
+connection node_1;
+SET GLOBAL sql_mode=0;
+SET sql_mode=DEFAULT;
+CREATE TABLE t (c INT,c2 BLOB,KEY k2 (c2 (1),c)) DEFAULT CHARSET=latin1 ROW_FORMAT=COMPACT;
+INSERT INTO t (c) VALUES (1),(1),(1),(1),(1);
+SELECT * FROM t;
+c	c2
+1	NULL
+1	NULL
+1	NULL
+1	NULL
+1	NULL
+DROP TABLE t;
+CREATE TABLE t (c INT,c2 BLOB NOT NULL,KEY k2 (c2 (1),c)) DEFAULT CHARSET=latin1 ROW_FORMAT=COMPACT;
+INSERT INTO t (c) VALUES (1),(1),(1),(1),(1);
+Warnings:
+Warning	1364	Field 'c2' doesn't have a default value
+SELECT * FROM t;
+c	c2
+1	
+1	
+1	
+1	
+1	
+DROP TABLE t;
+CREATE TABLE t (c INT,c2 VARCHAR(270),KEY k2 (c2 (1),c)) DEFAULT CHARSET=latin1 ROW_FORMAT=COMPACT;
+INSERT INTO t (c) VALUES (1),(1),(1),(1),(1);
+SELECT * FROM t;
+c	c2
+1	NULL
+1	NULL
+1	NULL
+1	NULL
+1	NULL
+DROP TABLE t;
+CREATE TABLE t (c INT,c2 VARCHAR(270) NOT NULL,KEY k2 (c2 (1),c)) DEFAULT CHARSET=latin1 ROW_FORMAT=COMPACT;
+INSERT INTO t (c) VALUES (1),(1),(1),(1),(1);
+Warnings:
+Warning	1364	Field 'c2' doesn't have a default value
+SELECT * FROM t;
+c	c2
+1	
+1	
+1	
+1	
+1	
+DROP TABLE t;
+CREATE TABLE t (c INT,c2 CHAR(80),KEY k2 (c2 (1),c)) DEFAULT CHARSET=latin1 ROW_FORMAT=COMPACT;
+INSERT INTO t (c) VALUES (1),(1),(1),(1),(1);
+SELECT * FROM t;
+c	c2
+1	NULL
+1	NULL
+1	NULL
+1	NULL
+1	NULL
+DROP TABLE t;
+CREATE TABLE t (c INT,c2 CHAR(80) NOT NULL,KEY k2 (c2 (1),c)) DEFAULT CHARSET=latin1 ROW_FORMAT=COMPACT;
+INSERT INTO t (c) VALUES (1),(1),(1),(1),(1);
+Warnings:
+Warning	1364	Field 'c2' doesn't have a default value
+SELECT * FROM t;
+c	c2
+1	
+1	
+1	
+1	
+1	
+DROP TABLE t;
+CREATE TABLE t (c INT,c2 TEXT,KEY k2 (c2 (1),c)) DEFAULT CHARSET=latin1 ROW_FORMAT=COMPACT;
+INSERT INTO t (c) VALUES (1),(1),(1),(1),(1);
+SELECT * FROM t;
+c	c2
+1	NULL
+1	NULL
+1	NULL
+1	NULL
+1	NULL
+DROP TABLE t;
+CREATE TABLE t (c INT,c2 TEXT NOT NULL,KEY k2 (c2 (1),c)) DEFAULT CHARSET=latin1 ROW_FORMAT=COMPACT;
+INSERT INTO t (c) VALUES (1),(1),(1),(1),(1);
+Warnings:
+Warning	1364	Field 'c2' doesn't have a default value
+SELECT * FROM t;
+c	c2
+1	
+1	
+1	
+1	
+1	
+DROP TABLE t;
+SET GLOBAL sql_mode=DEFAULT;
+CREATE TABLE t (c INT,c2 BLOB,KEY k2 (c2 (1),c)) DEFAULT CHARSET=latin1 ROW_FORMAT=COMPACT;
+INSERT INTO t (c) VALUES (1),(1),(1),(1),(1);
+SELECT * FROM t;
+c	c2
+1	NULL
+1	NULL
+1	NULL
+1	NULL
+1	NULL
+DROP TABLE t;
+CREATE TABLE t (c INT,c2 VARCHAR(270),KEY k2 (c2 (1),c)) DEFAULT CHARSET=latin1 ROW_FORMAT=COMPACT;
+INSERT INTO t (c) VALUES (1),(1),(1),(1),(1);
+SELECT * FROM t;
+c	c2
+1	NULL
+1	NULL
+1	NULL
+1	NULL
+1	NULL
+DROP TABLE t;
+CREATE TABLE t (c INT,c2 CHAR(80),KEY k2 (c2 (1),c)) DEFAULT CHARSET=latin1 ROW_FORMAT=COMPACT;
+INSERT INTO t (c) VALUES (1),(1),(1),(1),(1);
+SELECT * FROM t;
+c	c2
+1	NULL
+1	NULL
+1	NULL
+1	NULL
+1	NULL
+DROP TABLE t;
+CREATE TABLE t (c INT,c2 TEXT,KEY k2 (c2 (1),c)) DEFAULT CHARSET=latin1 ROW_FORMAT=COMPACT;
+INSERT INTO t (c) VALUES (1),(1),(1),(1),(1);
+SELECT * FROM t;
+c	c2
+1	NULL
+1	NULL
+1	NULL
+1	NULL
+1	NULL
+DROP TABLE t;

mysql-test/suite/galera/t/MDEV-30732.test

@@ -0,0 +1,55 @@
+--source include/galera_cluster.inc
+
+SET GLOBAL sql_mode=0;
+SET sql_mode=DEFAULT;
+CREATE TABLE t (c INT,c2 BLOB,KEY k2 (c2 (1),c)) DEFAULT CHARSET=latin1 ROW_FORMAT=COMPACT;
+INSERT INTO t (c) VALUES (1),(1),(1),(1),(1);
+SELECT * FROM t;
+DROP TABLE t;
+CREATE TABLE t (c INT,c2 BLOB NOT NULL,KEY k2 (c2 (1),c)) DEFAULT CHARSET=latin1 ROW_FORMAT=COMPACT;
+INSERT INTO t (c) VALUES (1),(1),(1),(1),(1);
+SELECT * FROM t;
+DROP TABLE t;
+CREATE TABLE t (c INT,c2 VARCHAR(270),KEY k2 (c2 (1),c)) DEFAULT CHARSET=latin1 ROW_FORMAT=COMPACT;
+INSERT INTO t (c) VALUES (1),(1),(1),(1),(1);
+SELECT * FROM t;
+DROP TABLE t;
+CREATE TABLE t (c INT,c2 VARCHAR(270) NOT NULL,KEY k2 (c2 (1),c)) DEFAULT CHARSET=latin1 ROW_FORMAT=COMPACT;
+INSERT INTO t (c) VALUES (1),(1),(1),(1),(1);
+SELECT * FROM t;
+DROP TABLE t;
+CREATE TABLE t (c INT,c2 CHAR(80),KEY k2 (c2 (1),c)) DEFAULT CHARSET=latin1 ROW_FORMAT=COMPACT;
+INSERT INTO t (c) VALUES (1),(1),(1),(1),(1);
+SELECT * FROM t;
+DROP TABLE t;
+CREATE TABLE t (c INT,c2 CHAR(80) NOT NULL,KEY k2 (c2 (1),c)) DEFAULT CHARSET=latin1 ROW_FORMAT=COMPACT;
+INSERT INTO t (c) VALUES (1),(1),(1),(1),(1);
+SELECT * FROM t;
+DROP TABLE t;
+CREATE TABLE t (c INT,c2 TEXT,KEY k2 (c2 (1),c)) DEFAULT CHARSET=latin1 ROW_FORMAT=COMPACT;
+INSERT INTO t (c) VALUES (1),(1),(1),(1),(1);
+SELECT * FROM t;
+DROP TABLE t;
+CREATE TABLE t (c INT,c2 TEXT NOT NULL,KEY k2 (c2 (1),c)) DEFAULT CHARSET=latin1 ROW_FORMAT=COMPACT;
+INSERT INTO t (c) VALUES (1),(1),(1),(1),(1);
+SELECT * FROM t;
+DROP TABLE t;
+
+SET GLOBAL sql_mode=DEFAULT;
+
+CREATE TABLE t (c INT,c2 BLOB,KEY k2 (c2 (1),c)) DEFAULT CHARSET=latin1 ROW_FORMAT=COMPACT;
+INSERT INTO t (c) VALUES (1),(1),(1),(1),(1);
+SELECT * FROM t;
+DROP TABLE t;
+CREATE TABLE t (c INT,c2 VARCHAR(270),KEY k2 (c2 (1),c)) DEFAULT CHARSET=latin1 ROW_FORMAT=COMPACT;
+INSERT INTO t (c) VALUES (1),(1),(1),(1),(1);
+SELECT * FROM t;
+DROP TABLE t;
+CREATE TABLE t (c INT,c2 CHAR(80),KEY k2 (c2 (1),c)) DEFAULT CHARSET=latin1 ROW_FORMAT=COMPACT;
+INSERT INTO t (c) VALUES (1),(1),(1),(1),(1);
+SELECT * FROM t;
+DROP TABLE t;
+CREATE TABLE t (c INT,c2 TEXT,KEY k2 (c2 (1),c)) DEFAULT CHARSET=latin1 ROW_FORMAT=COMPACT;
+INSERT INTO t (c) VALUES (1),(1),(1),(1),(1);
+SELECT * FROM t;
+DROP TABLE t;