Bug#14640599 MEMORY LEAK WHEN EXECUTING STORED ROUTINE EXCEPTION HANDLER

When a SP handler is activated, memory is allocated to hold the
MESSAGE_TEXT for the condition that caused the activation.

The problem was that this memory was allocated on the MEM_ROOT belonging
to the stored program. Since this MEM_ROOT is not freed until the
stored program ends, a stored program that causes lots of handler
activations can start using lots of memory. In 5.1 and earlier the
problem did not exist as no MESSAGE_TEXT was allocated if a condition
was raised with a handler present. However, this behavior lead to
a number of other issues such as Bug#23032.

This patch fixes the problem by allocating enough memory for the
necessary MESSAGE_TEXTs in the SP MEM_ROOT when the SP starts and
then re-using this memory each time a handler is activated.
      
This is the 5.5 version of the patch.

1 files changed, 3 insertions, 8 deletions

diff --git a/sql/sp_rcontext.cc b/sql/sp_rcontext.cc
index fba6a56b37c..09f48d824b0 100644
--- a/sql/sp_rcontext.cc
+++ b/sql/sp_rcontext.cc
@@ -67,19 +67,15 @@ sp_rcontext::~sp_rcontext()
 bool sp_rcontext::init(THD *thd)
 {
   uint handler_count= m_root_parsing_ctx->max_handler_index();
-  uint i;
 
   in_sub_stmt= thd->in_sub_stmt;
 
   if (init_var_table(thd) || init_var_items())
     return TRUE;
 
-  if (!(m_raised_conditions= new (thd->mem_root) MYSQL_ERROR[handler_count]))
+  if (!(m_raised_conditions= new (thd->mem_root) Sql_condition_info[handler_count]))
     return TRUE;
 
-  for (i= 0; i<handler_count; i++)
-    m_raised_conditions[i].init(thd->mem_root);
-
   return
     !(m_handler=
       (sp_handler_t*)thd->alloc(handler_count * sizeof(sp_handler_t))) ||
@@ -446,13 +442,12 @@ sp_rcontext::exit_handler()
   DBUG_VOID_RETURN;
 }
 
-MYSQL_ERROR*
-sp_rcontext::raised_condition() const
+Sql_condition_info* sp_rcontext::raised_condition() const
 {
   if (m_ihsp > 0)
   {
     uint hindex= m_in_handler[m_ihsp - 1].index;
-    MYSQL_ERROR *raised= & m_raised_conditions[hindex];
+    Sql_condition_info *raised= & m_raised_conditions[hindex];
     return raised;
   }