From 16aedd6d50fb2c6b18e10ac3fe12f3c137732f77 Mon Sep 17 00:00:00 2001
From: Anurag Shekhar <anurag.shekhar@sun.com>
Date: Wed, 4 Mar 2009 14:48:07 +0530
Subject: [PATCH] Bug#41305 server crashes when inserting duplicate row into a
 merge table

This problem comes while inserting a duplicate row in merge table
without key but the child table has a primary key.
While forming the error message handler tries to locate the key field
which is creating this problem but as there is no key on the merge
table there is a segmentation fault.
---
 mysql-test/r/merge.result         | 12 ++++++++++++
 mysql-test/t/merge.test           | 18 ++++++++++++++++++
 storage/myisammrg/ha_myisammrg.cc | 10 ++++++++++
 3 files changed, 40 insertions(+)

diff --git a/mysql-test/r/merge.result b/mysql-test/r/merge.result
index 3910536ee5d..d844abc1847 100644
--- a/mysql-test/r/merge.result
+++ b/mysql-test/r/merge.result
@@ -2103,4 +2103,16 @@ a
 UNLOCK TABLES;
 # drop the created tables
 DROP TABLE t1, t2, t3;
+# insert duplicate value in child table while merge table doesn't have key
+create table t1 (
+col1 int(10),
+primary key (col1)
+) ENGINE=MyISAM DEFAULT CHARSET=latin1;
+CREATE TABLE m1 (
+col1 int(10) NOT NULL
+) ENGINE=MRG_MyISAM DEFAULT CHARSET=latin1 INSERT_METHOD=LAST UNION=(t1);
+insert into m1 (col1) values (1);
+insert into m1 (col1) values (1);
+ERROR 23000: Duplicate entry '' for key '*UNKNOWN*'
+drop table m1, t1;
 End of 5.1 tests
diff --git a/mysql-test/t/merge.test b/mysql-test/t/merge.test
index 2fbfe2721e2..f12187ea143 100644
--- a/mysql-test/t/merge.test
+++ b/mysql-test/t/merge.test
@@ -1496,4 +1496,22 @@ UNLOCK TABLES;
 --echo # drop the created tables
 DROP TABLE t1, t2, t3;
 
+#
+# Bug #41305 server crashes when inserting duplicate row into a merge table
+#
+--echo # insert duplicate value in child table while merge table doesn't have key
+create table t1 (
+        col1 int(10),
+        primary key (col1)
+) ENGINE=MyISAM DEFAULT CHARSET=latin1;
+
+CREATE TABLE m1 (
+  col1 int(10) NOT NULL
+) ENGINE=MRG_MyISAM DEFAULT CHARSET=latin1 INSERT_METHOD=LAST UNION=(t1);
+
+insert into m1 (col1) values (1);
+--error ER_DUP_ENTRY
+insert into m1 (col1) values (1);
+
+drop table m1, t1;
 --echo End of 5.1 tests
diff --git a/storage/myisammrg/ha_myisammrg.cc b/storage/myisammrg/ha_myisammrg.cc
index d674f6bc150..5bd7c7dd05c 100644
--- a/storage/myisammrg/ha_myisammrg.cc
+++ b/storage/myisammrg/ha_myisammrg.cc
@@ -872,6 +872,16 @@ int ha_myisammrg::info(uint flag)
     table->s->crashed= 1;
 #endif
   stats.data_file_length= mrg_info.data_file_length;
+  if (mrg_info.errkey >= table_share->keys) 
+  {
+    /*
+     If value of errkey is higher than the number of keys
+     on the table set errkey to MAX_KEY. This will be
+     treated as unknown key case and error message generator
+     won't try to locate key causing segmentation fault.
+    */
+    mrg_info.errkey= MAX_KEY;
+  }
   errkey= mrg_info.errkey;
   table->s->keys_in_use.set_prefix(table->s->keys);
   stats.mean_rec_length= mrg_info.reclength;