Fixes for bugs #2274 "mysqld gets SIGSEGV during processing of malformed

COM_EXECUTE packet" and #2795 "prepare + execute without bind_param crashes
 server" and #2473 "seg fault running tests/client_test.c": 
- length checking added to packet parser 
- default impelemntation of Item_param::set_param_func will work in
case of malformed packet.
No test cases are possible in our test suite, as there are no tests 
operating on protocol layer.


sql/item.cc:
  Default set_param function implemented: this is to not sigsegv in case
  of malformed packet with no parameters data.
sql/item.h:
  - Item_param constructor moved to .cc to be able to assign set_param_func.
  - now embedded and ordinary versions of set_param have the same signature.
sql/mysql_priv.h:
  mysql_stmt_execute now requires packet_length
sql/sql_parse.cc:
  mysql_stmt_execute now requires packet length.
sql/sql_prepare.cc:
  - length checking added to all functions working with network packet.
  - set_param_func's in embedded and ordinary version now have the same 
  signature

sql/item.cc

@@ -517,7 +517,33 @@ String *Item_null::val_str(String *str)
 { null_value=1; return 0;}
 
 
-/* Item_param related */
+/*********************** Item_param related ******************************/
+
+/* 
+  Default function of Item_param::set_param_func, so in case
+  of malformed packet the server won't SIGSEGV
+*/
+
+static void
+default_set_param_func(Item_param *param,
+                       uchar **pos __attribute__((unused)),
+                       ulong len __attribute__((unused)))
+{
+  param->set_null();
+}
+
+Item_param::Item_param(unsigned position) :
+  value_is_set(FALSE),
+  item_result_type(STRING_RESULT),
+  item_type(STRING_ITEM),
+  item_is_time(FALSE),
+  long_data_supplied(FALSE),
+  pos_in_query(position),
+  set_param_func(default_set_param_func)
+{
+  name= (char*) "?";
+}
+
 void Item_param::set_null()
 {
   DBUG_ENTER("Item_param::set_null");

sql/item.h

@@ -348,16 +348,7 @@ class Item_param :public Item
   bool long_data_supplied;
   uint pos_in_query;
 
-  Item_param(uint position)
-  { 
-    name= (char*) "?";
-    pos_in_query= position;
-    item_type= STRING_ITEM;
-    item_result_type = STRING_RESULT;
-    item_is_time= false;
-    long_data_supplied= false;
-    value_is_set= 0;
-  }
+  Item_param(uint position);
   enum Type type() const { return item_type; }
   double val();
   longlong val_int();
@@ -374,11 +365,14 @@ class Item_param :public Item
   void set_time(TIME *tm, timestamp_type type);
   bool get_time(TIME *tm);
   void reset() {}
-#ifndef EMBEDDED_LIBRARY
-  void (*set_param_func)(Item_param *param, uchar **pos);
-#else
-  void (*set_param_func)(Item_param *param, uchar **pos, ulong data_len);
-#endif
+  /*
+    Assign placeholder value from bind data.
+    Note, that 'len' has different semantics in embedded library (as we
+    don't need to check that packet is not broken there). See
+    sql_prepare.cc for details.
+  */
+  void (*set_param_func)(Item_param *param, uchar **pos, ulong len);
+
   enum Item_result result_type () const
   { return item_result_type; }
   String *query_val_str(String *str);

sql/mysql_priv.h

@@ -621,7 +621,7 @@ int mysqld_help (THD *thd, const char *text);
 
 /* sql_prepare.cc */
 void mysql_stmt_prepare(THD *thd, char *packet, uint packet_length);
-void mysql_stmt_execute(THD *thd, char *packet);
+void mysql_stmt_execute(THD *thd, char *packet, uint packet_length);
 void mysql_stmt_free(THD *thd, char *packet);
 void mysql_stmt_reset(THD *thd, char *packet);
 void mysql_stmt_get_longdata(THD *thd, char *pos, ulong packet_length);

sql/sql_parse.cc

@@ -1405,7 +1405,7 @@ bool dispatch_command(enum enum_server_command command, THD *thd,
   }
   case COM_EXECUTE:
   {
-    mysql_stmt_execute(thd, packet);
+    mysql_stmt_execute(thd, packet, packet_length);
     break;
   }
   case COM_LONG_DATA:

sql/sql_prepare.cc

@@ -94,7 +94,8 @@ class Prepared_statement: public Statement
   bool long_data_used;
   bool log_full_query;
 #ifndef EMBEDDED_LIBRARY
-  bool (*set_params)(Prepared_statement *st, uchar *pos, uchar *read_pos);
+  bool (*set_params)(Prepared_statement *st, uchar *data, uchar *data_end,
+                     uchar *read_pos);
 #else
   bool (*set_params_data)(Prepared_statement *st);
 #endif
@@ -117,14 +118,6 @@ inline bool is_param_null(const uchar *pos, ulong param_no)
 
 enum { STMT_QUERY_LOG_LENGTH= 8192 };
 
-#ifdef EMBEDDED_LIBRARY
-#define SET_PARAM_FUNCTION(fn_name) \
-static void fn_name(Item_param *param, uchar **pos, ulong data_len)
-#else
-#define SET_PARAM_FUNCTION(fn_name) \
-static void fn_name(Item_param *param, uchar **pos)
-#endif
-
 enum enum_send_error { DONT_SEND_ERROR= 0, SEND_ERROR };
 
 /*
@@ -186,29 +179,38 @@ static bool send_prep_stmt(Prepared_statement *stmt,
 */
 
 #ifndef EMBEDDED_LIBRARY
-static ulong get_param_length(uchar **packet)
+static ulong get_param_length(uchar **packet, ulong len)
 {
   reg1 uchar *pos= *packet;
+  if (len < 1)
+    return 0;
   if (*pos < 251)
   {
     (*packet)++;
     return (ulong) *pos;
   }
+  if (len < 3)
+    return 0;
   if (*pos == 252)
   {
     (*packet)+=3;
     return (ulong) uint2korr(pos+1);
   }
+  if (len < 4)
+    return 0;
   if (*pos == 253)
   {
     (*packet)+=4;
     return (ulong) uint3korr(pos+1);
   }
+  if (len < 5)
+    return 0;
   (*packet)+=9; // Must be 254 when here 
+  /* TODO: why uint4korr here? (should be uint8korr) */
   return (ulong) uint4korr(pos+1);
 }
 #else
-#define get_param_length(A) data_len
+#define get_param_length(packet, len) len
 #endif /*!EMBEDDED_LIBRARY*/
 
  /*
@@ -230,55 +232,80 @@ static ulong get_param_length(uchar **packet)
     none
 */
 
-SET_PARAM_FUNCTION(set_param_tiny)
+void set_param_tiny(Item_param *param, uchar **pos, ulong len)
 {
+#ifndef EMBEDDED_LIBRARY
+  if (len < 1)
+    return;
+#endif
   param->set_int((longlong)(**pos));
   *pos+= 1;
 }
 
-SET_PARAM_FUNCTION(set_param_short)
+void set_param_short(Item_param *param, uchar **pos, ulong len)
 {
+#ifndef EMBEDDED_LIBRARY
+  if (len < 2)
+    return;
+#endif
   param->set_int((longlong)sint2korr(*pos));
   *pos+= 2;
 }
 
-SET_PARAM_FUNCTION(set_param_int32)
+void set_param_int32(Item_param *param, uchar **pos, ulong len)
 {
+#ifndef EMBEDDED_LIBRARY
+  if (len < 4)
+    return;
+#endif
   param->set_int((longlong)sint4korr(*pos));
   *pos+= 4;
 }
 
-SET_PARAM_FUNCTION(set_param_int64)
+void set_param_int64(Item_param *param, uchar **pos, ulong len)
 {
+#ifndef EMBEDDED_LIBRARY
+  if (len < 8)
+    return;
+#endif
   param->set_int((longlong)sint8korr(*pos));
   *pos+= 8;
 }
 
-SET_PARAM_FUNCTION(set_param_float)
+void set_param_float(Item_param *param, uchar **pos, ulong len)
 {
+#ifndef EMBEDDED_LIBRARY
+  if (len < 4)
+    return;
+#endif
   float data;
   float4get(data,*pos);
   param->set_double((double) data);
   *pos+= 4;
 }
 
-SET_PARAM_FUNCTION(set_param_double)
+void set_param_double(Item_param *param, uchar **pos, ulong len)
 {
+#ifndef EMBEDDED_LIBRARY
+  if (len < 8)
+    return;
+#endif
   double data;
   float8get(data,*pos);
   param->set_double((double) data);
   *pos+= 8;
 }
 
-SET_PARAM_FUNCTION(set_param_time)
+void set_param_time(Item_param *param, uchar **pos, ulong len)
 {
   ulong length;
 
-  if ((length= get_param_length(pos)))
+  if ((length= get_param_length(pos, len)) >= 8)
   {
     uchar *to= *pos;
     TIME  tm;
     
+    /* TODO: why length is compared with 8 here? */
     tm.second_part= (length > 8 ) ? (ulong) sint4korr(to+7): 0;
 
     tm.day=    (ulong) sint4korr(to+1);
@@ -294,11 +321,11 @@ SET_PARAM_FUNCTION(set_param_time)
   *pos+= length;
 }
 
-SET_PARAM_FUNCTION(set_param_datetime)
+void set_param_datetime(Item_param *param, uchar **pos, ulong len)
 {
   uint length;
  
-  if ((length= get_param_length(pos)))
+  if ((length= get_param_length(pos, len)) >= 4)
   {
     uchar *to= *pos;
     TIME  tm;
@@ -324,11 +351,11 @@ SET_PARAM_FUNCTION(set_param_datetime)
   *pos+= length;
 }
 
-SET_PARAM_FUNCTION(set_param_date)
+void set_param_date(Item_param *param, uchar **pos, ulong len)
 {
   ulong length;
  
-  if ((length= get_param_length(pos)))
+  if ((length= get_param_length(pos, len)) >= 4)
   {
     uchar *to= *pos;
     TIME tm;
@@ -346,11 +373,11 @@ SET_PARAM_FUNCTION(set_param_date)
   *pos+= length;
 }
 
-SET_PARAM_FUNCTION(set_param_str)
+void set_param_str(Item_param *param, uchar **pos, ulong len)
 {
-  ulong len= get_param_length(pos);
-  param->set_value((const char *)*pos, len);
-  *pos+= len;
+  ulong length= get_param_length(pos, len);
+  param->set_value((const char *)*pos, length);
+  *pos+= length;
 }
 
 static void setup_one_conversion_function(Item_param *param, uchar param_type)
@@ -405,8 +432,8 @@ static void setup_one_conversion_function(Item_param *param, uchar param_type)
   and if binary/update log is set, generate the valid query.
 */
 
-static bool insert_params_withlog(Prepared_statement *stmt, uchar *pos,
-                                  uchar *read_pos)
+static bool insert_params_withlog(Prepared_statement *stmt, uchar *null_array,
+                                  uchar *read_pos, uchar *data_end)
 {
   THD  *thd= stmt->thd;
   Item_param **begin= stmt->param_array;
@@ -428,7 +455,7 @@ static bool insert_params_withlog(Prepared_statement *stmt, uchar *pos,
       res= param->query_val_str(&str);
     else
     {
-      if (is_param_null(pos, it - begin))
+      if (is_param_null(null_array, it - begin))
       {
         param->maybe_null= param->null_value= 1;
         res= &my_null_string;
@@ -436,7 +463,9 @@ static bool insert_params_withlog(Prepared_statement *stmt, uchar *pos,
       else
       {
         param->maybe_null= param->null_value= 0;
-        param->set_param_func(param, &read_pos);
+        if (read_pos >= data_end)
+          DBUG_RETURN(1);
+        param->set_param_func(param, &read_pos, data_end - read_pos);
         res= param->query_val_str(&str);
       }
     }
@@ -452,8 +481,8 @@ static bool insert_params_withlog(Prepared_statement *stmt, uchar *pos,
 }
 
 
-static bool insert_params(Prepared_statement *stmt, uchar *pos,
-                          uchar *read_pos)
+static bool insert_params(Prepared_statement *stmt, uchar *null_array,
+                          uchar *read_pos, uchar *data_end)
 {
   Item_param **begin= stmt->param_array;
   Item_param **end= begin + stmt->param_count;
@@ -465,20 +494,23 @@ static bool insert_params(Prepared_statement *stmt, uchar *pos,
     Item_param *param= *it;
     if (!param->long_data_supplied)
     {
-      if (is_param_null(pos, it - begin))
+      if (is_param_null(null_array, it - begin))
         param->maybe_null= param->null_value= 1;
       else
       {
         param->maybe_null= param->null_value= 0;
-        param->set_param_func(param, &read_pos);
+        if (read_pos >= data_end)
+          DBUG_RETURN(1);
+        param->set_param_func(param, &read_pos, data_end - read_pos);
       }
     }
   }
   DBUG_RETURN(0);
 }
 
+
 static bool setup_conversion_functions(Prepared_statement *stmt,
-                                       uchar **data)
+                                       uchar **data, uchar *data_end)
 {
   /* skip null bits */
   uchar *read_pos= *data + (stmt->param_count+7) / 8;
@@ -495,6 +527,8 @@ static bool setup_conversion_functions(Prepared_statement *stmt,
     Item_param **end= it + stmt->param_count;
     for (; it < end; ++it)
     {
+      if (read_pos >= data_end)
+        DBUG_RETURN(1);
       setup_one_conversion_function(*it, *read_pos);
       read_pos+= 2;
     }
@@ -1072,7 +1106,7 @@ static void reset_stmt_for_execute(Prepared_statement *stmt)
 */
 
 
-void mysql_stmt_execute(THD *thd, char *packet)
+void mysql_stmt_execute(THD *thd, char *packet, uint packet_length)
 {
   ulong stmt_id= uint4korr(packet);
   Prepared_statement *stmt;
@@ -1097,10 +1131,11 @@ void mysql_stmt_execute(THD *thd, char *packet)
 #ifndef EMBEDDED_LIBRARY
   if (stmt->param_count)
   {
+    uchar *packet_end= (uchar *) packet + packet_length - 1;
     packet+= 4;
     uchar *null_array= (uchar *) packet;
-    if (setup_conversion_functions(stmt, (uchar **) &packet) ||
-        stmt->set_params(stmt, null_array, (uchar *) packet)) 
+    if (setup_conversion_functions(stmt, (uchar **) &packet, packet_end) ||
+        stmt->set_params(stmt, null_array, (uchar *) packet, packet_end)) 
       goto set_params_data_err;
   }
 #else
@@ -1159,6 +1194,7 @@ void mysql_stmt_execute(THD *thd, char *packet)
 
 void mysql_stmt_reset(THD *thd, char *packet)
 {
+  /* There is always space for 4 bytes in buffer */
   ulong stmt_id= uint4korr(packet);
   Prepared_statement *stmt;
   
@@ -1189,6 +1225,7 @@ void mysql_stmt_reset(THD *thd, char *packet)
 
 void mysql_stmt_free(THD *thd, char *packet)
 {
+  /* There is always space for 4 bytes in packet buffer */
   ulong stmt_id= uint4korr(packet);
   Prepared_statement *stmt;