Details
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Bug
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Status: Closed (View Workflow)
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Major
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Resolution: Fixed
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10.1.24, 10.0.31
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Ubuntu 14.04
Description
The PCRE recursion limit has apparently decreased in 10.1. There is no way to increase this limit through configuration.
eg:
MariaDB [10_1_sandbox]> SELECT CONCAT(REPEAT('100,',98),'101') RLIKE '^(([1-9][0-9]*),)*[1-9][0-9]*$' TEST;
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+------+
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| TEST |
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+------+
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| 1 |
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+------+
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1 row in set (0.02 sec)
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|
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MariaDB [10_1_sandbox]> SELECT CONCAT(REPEAT('100,',99),'101') RLIKE '^(([1-9][0-9]*),)*[1-9][0-9]*$' TEST;
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+------+
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| TEST |
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+------+
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| 0 |
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+------+
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1 row in set, 1 warning (0.02 sec)
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|
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MariaDB [sandbox]> show warnings;
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+---------+------+--------------------------------------------------------------------+
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| Level | Code | Message |
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+---------+------+--------------------------------------------------------------------+
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| Warning | 1139 | Got error 'pcre_exec: recursion limit of 100 exceeded' from regexp |
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+---------+------+--------------------------------------------------------------------+
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1 row in set (0.15 sec)
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In 10.0:
MariaDB [10_0_sandbox]> SELECT CONCAT(REPEAT('100,',99),'101') RLIKE '^(([1-9][0-9]*),)*[1-9][0-9]*$' TEST;
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+------+
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| TEST |
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+------+
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| 1 |
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+------+
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1 row in set (0.14 sec)
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Attachments
Issue Links
- relates to
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- Closed
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Activity
So Regexp_processor_pcre::set_recursion_limit(THD *) was added however never called and hence the default 100L being used. Would this need to be called by fix_fields (which has a THD arg)?
Few commits are relevant commits d672f88ef73e3fc566a382600968c3e51249de1a..52aa200919b1fd9357c05bcdfc66a42e51f242b3
It looks like the limit was not increased enough.
The warning on 10.1.26 is now:
MariaDB [test]> SELECT CONCAT(REPEAT('0,1,21,',99),'101') RLIKE '^([0-9]+,)*[0-9]+$' TEST;
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+------+
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| TEST |
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+------+
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| 0 |
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+------+
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1 row in set, 1 warning (0.01 sec)
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MariaDB [test]> show warnings;
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+---------+------+--------------------------------------------------------------------+
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| Level | Code | Message |
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+---------+------+--------------------------------------------------------------------+
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| Warning | 1139 | Got error 'pcre_exec: recursion limit of 519 exceeded' from regexp |
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+---------+------+--------------------------------------------------------------------+
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1 row in set (0.00 sec)
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This works on 10.0.28
MariaDB [staging]> SELECT CONCAT(REPEAT('0,1,21,',99),'101') RLIKE '^([0-9]+,)*[0-9]+$' TEST;
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+------+
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| TEST |
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+------+
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| 1 |
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+------+
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1 row in set (0.18 sec)
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Is this configurable?
Yes, it's automatically detected based on your stack size (thread stack size divided by prce frame size, minus some safety margin), few more levels of recursion would've crashed your server.
Increase thread stack — that should help. See the --thread-stack option.
The difference in behavior is reproducible, it was introduced by this revision:
commit d672f88ef73e3fc566a382600968c3e51249de1aAuthor: Daniel Black <grooverdan@users.sourceforge.net>Date: Sat Apr 8 22:47:56 2017 +1000MDEV-12420: PCRE stack overflowI will leave it to danblack and serg to decide whether this particular effect was desirable.