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Bug#25541037: MYSQL BUG ON DELETE

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Description:- MyISAM table gets corrupted with concurrent
executions of INSERT, DELETE statements in a particular
sequence.

Analysis:- Due to the inappropriate manipulation of w_lock
and r_lock associated with a MyISAM table, there arises a
scenario where the table's state information becomes
invalid.

Fix:- A lock is introduced to resolve this issue.
This commit is contained in:
Arun Kuruvila 2018-05-21 08:42:45 +05:30
parent bbc2e37fe4
commit bd5ca6acec
3 changed files with 15 additions and 3 deletions
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6
storage/myisam/ha_myisam.cc
View file

@ -1,5 +1,5 @@
/*
Copyright (c) 2000, 2016, Oracle and/or its affiliates. All rights reserved.
Copyright (c) 2000, 2018, Oracle and/or its affiliates. All rights reserved.
This program is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
@ -1172,10 +1172,14 @@ int ha_myisam::repair(THD *thd, MI_CHECK &param, bool do_optimize)
if (file->s->base.auto_key)
update_auto_increment_key(&param, file, 1);
if (optimize_done)
{
mysql_mutex_lock(&share->intern_lock);
error = update_state_info(&param, file,
UPDATE_TIME | UPDATE_OPEN_COUNT |
(local_testflag &
T_STATISTICS ? UPDATE_STAT : 0));
mysql_mutex_unlock(&share->intern_lock);
}
info(HA_STATUS_NO_LOCK | HA_STATUS_TIME | HA_STATUS_VARIABLE |
HA_STATUS_CONST);
if (rows != file->state->records && ! (param.testflag & T_VERY_SILENT))

6
storage/myisam/mi_check.c
View file

@ -1,5 +1,5 @@
/*
Copyright (c) 2000, 2016, Oracle and/or its affiliates. All rights reserved.
Copyright (c) 2000, 2018, Oracle and/or its affiliates. All rights reserved.
This program is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
@ -4474,6 +4474,10 @@ int update_state_info(MI_CHECK *param, MI_INFO *info,uint update)
int error;
uint r_locks=share->r_locks,w_locks=share->w_locks;
share->r_locks= share->w_locks= share->tot_locks= 0;
DBUG_EXECUTE_IF("simulate_incorrect_share_wlock_value",
DEBUG_SYNC_C("after_share_wlock_set_to_0"););
error=_mi_writeinfo(info,WRITEINFO_NO_UNLOCK);
share->r_locks=r_locks;
share->w_locks=w_locks;

6
storage/myisam/mi_locking.c
View file

@ -1,4 +1,4 @@
/* Copyright (c) 2000, 2017, Oracle and/or its affiliates. All rights reserved.
/* Copyright (c) 2000, 2018, Oracle and/or its affiliates. All rights reserved.
This program is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
@ -229,6 +229,10 @@ int mi_lock_database(MI_INFO *info, int lock_type)
info->invalidator=info->s->invalidator;
share->w_locks++;
share->tot_locks++;
DBUG_EXECUTE_IF("simulate_incorrect_share_wlock_value",
DEBUG_SYNC_C("after_share_wlock_increment"););
info->s->in_use= list_add(info->s->in_use, &info->in_use);
break;
default: