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  1. MariaDB Server
  2. MDEV-6572

"USE dbname" with a bad sequence erroneously connects to a wrong database

        Details

        • Type: Bug
        • Status: Closed
        • Priority: Major
        • Resolution: Fixed
        • Affects Version/s: 5.3.12, 5.5.39, 10.0.14
        • Fix Version/s: 10.1.4
        • Component/s: Character Sets
        • Labels:
          None

          Description

          I create a database with some question marks in the name:

          DROP DATABASE IF EXISTS `test????`;
CREATE DATABASE `test????`;

          Now I run a "USE" query with a bad byte sequence:

          SET NAMES utf8;
USE `test😁`;
SELECT DATABASE(), HEX(DATABASE());

          (notice. '😁' is a four-byte UTF-8 character, which is considered as a wrong
          byte sequence by MariaDB's 3-byte "utf8").

          It erroneously connects to the database 'test????':

          ariaDB [(none)]> SET NAMES utf8;
Query OK, 0 rows affected (0.00 sec)

MariaDB [(none)]> USE `test😁`;
Database changed
MariaDB [test😁]> SELECT DATABASE(), HEX(DATABASE());
+------------+------------------+
| DATABASE() | HEX(DATABASE())  |
+------------+------------------+
| test????   | 746573743F3F3F3F |
+------------+------------------+
1 row in set (0.00 sec)

          The correct behaviour would be report either "unknown database",
          or "bad database name" or "Invalid utf8 character string: 'test\xF0\x9F\x98\x81'".

          The latter would be consistent with what's reported on attempt to
          create a database with such a broken name:

          MariaDB [test]> CREATE DATABASE `test😁`;
ERROR 1300 (HY000): Invalid utf8 character string: 'test\xF0\x9F\x98\x81'

          A similar problem also happens with table names.
          I create a table with question marks in its name:

          SET NAMES utf8;
DROP TABLE IF EXISTS `test????`;
CREATE TABLE `test????` (a INT);
INSERT INTO `test????` values (10);

          Now I change the connection character set to utf8mb4 and run a SELECT query:

          SET NAMES utf8mb4;
SELECT * FROM `test😁😁😁😁`;

          It returns rows from the table `test????`:

          +------+
| a    |
+------+
|   10 |
+------+
1 row in set (0.01 sec)

          The expected behaviour would be to return some error.

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                Issue Links

                is blocked by

                Bug - A problem which impairs or prevents the functions of the product. MDEV-6566 Different INSERT behaviour on bad bytes with and without character set conversion

                • Major - Major loss of function.
                • Closed

                Task - A task that needs to be done. MDEV-6643 Improve performance of string processing in the parser

                • Major - Major loss of function.
                • In Review

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                    • Assignee:
                      bar Alexander Barkov
                      Reporter:
                      bar Alexander Barkov
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                      Dates

                      • Created:
                        Updated:
                        Resolved: