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A fix for Bug#19022 "Memory bug when switching db during trigger execution".

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No test case as the bug is in an existing test case (rpl_trigger.test
when it is run under valgrind).
The warning was caused by memory corruption in replication slave: thd->db
was pointing at a stack address that was previously used by 
sp_head::execute()::old_db. This happened because mysql_change_db
behaved differently in replication slave and did not make a copy of the 
argument to assign to thd->db. 
The solution is to always free the old value of thd->db and allocate a new
copy, regardless whether we're running in a replication slave or not.
This commit is contained in:
konstantin@mysql.com
2006-06-28 23:47:45 +04:00
parent 9bcb24b65e
commit 55d148c5c2
5 changed files with 111 additions and 121 deletions
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24
sql/sql_class.h
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@ -1574,21 +1574,23 @@ public:
/*
Initialize the current database from a NULL-terminated string with length
If we run out of memory, we free the current database and return TRUE.
This way the user will notice the error as there will be no current
database selected (in addition to the error message set by malloc).
*/
void set_db(const char *new_db, uint new_db_len)
bool set_db(const char *new_db, uint new_db_len)
{
if (new_db)
/* Do not reallocate memory if current chunk is big enough. */
if (db && new_db && db_length >= new_db_len)
memcpy(db, new_db, new_db_len+1);
else
{
/* Do not reallocate memory if current chunk is big enough. */
if (db && db_length >= new_db_len)
memcpy(db, new_db, new_db_len+1);
else
{
safeFree(db);
db= my_strdup_with_length(new_db, new_db_len, MYF(MY_WME));
}
db_length= db ? new_db_len: 0;
x_free(db);
db= new_db ? my_strdup_with_length(new_db, new_db_len, MYF(MY_WME)) :
NULL;
}
db_length= db ? new_db_len : 0;
return new_db && !db;
}
void reset_db(char *new_db, uint new_db_len)
{