Bug #19216: Client crashes on long SELECT

 The server sends a number of columns to the client.
 It uses a limited "fast" function for that instead of the
 general one. This fast function cannot send numbers larger 
 than 2 bytes. 
 This causes the client to expect smaller number of columns. 
 The client writes outside of the allocated memory buffer 
 as a result.
 Fixed the server to use the general function to send column
 count.
 Fixed the client to check the column count before writing
 column data. 

mysql-test/t/mysql_client.test

@@ -33,3 +33,21 @@
 #
 --exec echo 'help' | $MYSQL   >  $MYSQLTEST_VARDIR/tmp/bug20328.tmp
 --exec echo 'help ' | $MYSQL  >  $MYSQLTEST_VARDIR/tmp/bug20328.tmp
+
+#
+# Bug #19216: Client crashes on long SELECT
+#
+--exec echo "select" > $MYSQLTEST_VARDIR/tmp/b19216.tmp
+# 3400 * 20 makes 68000 columns that is more than the max number that can fit 
+# in a 16 bit number.
+let $i= 3400;
+while ($i)
+{
+  --exec echo "'a','a','a','a','a','a','a','a','a','a','a','a','a','a','a','a','a','a','a','a'," >> $MYSQLTEST_VARDIR/tmp/b19216.tmp
+  dec $i;
+}
+
+--exec echo "'b';" >> $MYSQLTEST_VARDIR/tmp/b19216.tmp
+--disable_query_log
+--exec $MYSQL < $MYSQLTEST_VARDIR/tmp/b19216.tmp >/dev/null
+--enable_query_log

sql-common/client.c

@@ -1173,6 +1173,8 @@ unpack_fields(MYSQL_DATA *data,MEM_ROOT *alloc,uint fields,
     for (row=data->data; row ; row = row->next,field++)
     {
       uchar *pos;
+      /* fields count may be wrong */
+      DBUG_ASSERT ((field - result) < fields);
       cli_fetch_lengths(&lengths[0], row->data, default_value ? 8 : 7);
       field->catalog  = strdup_root(alloc,(char*) row->data[0]);
       field->db       = strdup_root(alloc,(char*) row->data[1]);

sql/protocol.cc

@@ -43,7 +43,7 @@ bool Protocol_prep::net_store_data(const char *from, uint length)
       packet->realloc(packet_length+9+length))
     return 1;
   char *to=(char*) net_store_length((char*) packet->ptr()+packet_length,
-				    (ulonglong) length);
+				    length);
   memcpy(to,from,length);
   packet->length((uint) (to+length-packet->ptr()));
   return 0;
@@ -297,8 +297,8 @@ send_ok(THD *thd, ha_rows affected_rows, ulonglong id, const char *message)
     DBUG_VOID_RETURN;
 
   buff[0]=0;					// No fields
-  pos=net_store_length(buff+1,(ulonglong) affected_rows);
-  pos=net_store_length(pos, (ulonglong) id);
+  pos=net_store_length(buff+1,affected_rows);
+  pos=net_store_length(pos, id);
   if (thd->client_capabilities & CLIENT_PROTOCOL_41)
   {
     DBUG_PRINT("info",
@@ -416,7 +416,7 @@ bool send_old_password_request(THD *thd)
   ulonglong for bigger numbers.
 */
 
-char *net_store_length(char *pkg, uint length)
+static char *net_store_length_fast(char *pkg, uint length)
 {
   uchar *packet=(uchar*) pkg;
   if (length < 251)
@@ -439,7 +439,7 @@ char *net_store_length(char *pkg, uint length)
 
 char *net_store_data(char *to,const char *from, uint length)
 {
-  to=net_store_length(to,length);
+  to=net_store_length_fast(to,length);
   memcpy(to,from,length);
   return to+length;
 }
@@ -448,7 +448,7 @@ char *net_store_data(char *to,int32 from)
 {
   char buff[20];
   uint length=(uint) (int10_to_str(from,buff,10)-buff);
-  to=net_store_length(to,length);
+  to=net_store_length_fast(to,length);
   memcpy(to,buff,length);
   return to+length;
 }
@@ -457,7 +457,7 @@ char *net_store_data(char *to,longlong from)
 {
   char buff[22];
   uint length=(uint) (longlong10_to_str(from,buff,10)-buff);
-  to=net_store_length(to,length);
+  to=net_store_length_fast(to,length);
   memcpy(to,buff,length);
   return to+length;
 }
@@ -520,7 +520,7 @@ bool Protocol::send_fields(List<Item> *list, uint flag)
 
   if (flag & 1)
   {				// Packet with number of elements
-    char *pos=net_store_length(buff, (uint) list->elements);
+    char *pos=net_store_length(buff, list->elements);
     (void) my_net_write(&thd->net, buff,(uint) (pos-buff));
   }
 
@@ -648,7 +648,7 @@ bool Protocol::send_records_num(List<Item> *list, ulonglong records)
 {
   char *pos;
   char buff[20];
-  pos=net_store_length(buff, (uint) list->elements);
+  pos=net_store_length(buff, list->elements);
   pos=net_store_length(pos, records);
   return my_net_write(&thd->net, buff,(uint) (pos-buff));
 }

sql/protocol.h

@@ -177,7 +177,6 @@ void send_ok(THD *thd, ha_rows affected_rows=0L, ulonglong id=0L,
 	     const char *info=0);
 void send_eof(THD *thd, bool no_flush=0);
 bool send_old_password_request(THD *thd);
-char *net_store_length(char *packet,uint length);
 char *net_store_data(char *to,const char *from, uint length);
 char *net_store_data(char *to,int32 from);
 char *net_store_data(char *to,longlong from);