Fix for Lbug:#686010 maria.optimize corrupts stack around alloca() call

storage/maria/ma_check.c:
  Allocate also memory for nodflag and transid's
storage/maria/ma_write.c:
  Allow nodflag and transid as part of key.
  (This has nothing to do with the bug report, but it's a safer check).
storage/maria/maria_def.h:
  Define MARIA_MAX_POINTER_LENGTH (length of pointer to node)
  Added node pointer length to MARIA_INDEX_OVERHEAD_SIZE, as this is part of the key.
  (Safety fix)

storage/maria/ma_check.c

@@ -3133,7 +3133,8 @@ static int sort_one_index(HA_CHECK *param, MARIA_HA *info,
   key.keyinfo= keyinfo;
 
   if (!(buff= (uchar*) my_alloca((uint) keyinfo->block_length +
-                                 keyinfo->maxlength)))
+                                 keyinfo->maxlength +
+                                 MARIA_INDEX_OVERHEAD_SIZE)))
   {
     _ma_check_print_error(param,"Not enough memory for key block");
     DBUG_RETURN(-1);

storage/maria/ma_write.c

@@ -22,8 +22,6 @@
 #include "ma_key_recover.h"
 #include "ma_blockrec.h"
 
-#define MAX_POINTER_LENGTH 8
-
 	/* Functions declared in this file */
 
 static int w_search(MARIA_HA *info, uint32 comp_flag,
@@ -802,7 +800,7 @@ int _ma_insert(register MARIA_HA *info, MARIA_KEY *key,
 #endif
   if (t_length > 0)
   {
-    if (t_length >= keyinfo->maxlength*2+MAX_POINTER_LENGTH)
+    if (t_length >= keyinfo->maxlength*2+MARIA_INDEX_OVERHEAD_SIZE)
     {
       my_errno=HA_ERR_CRASHED;
       DBUG_RETURN(-1);
@@ -811,7 +809,7 @@ int _ma_insert(register MARIA_HA *info, MARIA_KEY *key,
   }
   else
   {
-    if (-t_length >= keyinfo->maxlength*2+MAX_POINTER_LENGTH)
+    if (-t_length >= keyinfo->maxlength*2+MARIA_INDEX_OVERHEAD_SIZE)
     {
       my_errno=HA_ERR_CRASHED;
       DBUG_RETURN(-1);

storage/maria/maria_def.h

@@ -152,11 +152,13 @@ typedef struct st_maria_state_info
 #define MARIA_COLUMNDEF_SIZE	(2*7+1+1+4)
 #define MARIA_BASE_INFO_SIZE	(MY_UUID_SIZE + 5*8 + 6*4 + 11*2 + 6 + 5*2 + 1 + 16)
 #define MARIA_INDEX_BLOCK_MARGIN 16	/* Safety margin for .MYI tables */
+#define MARIA_MAX_POINTER_LENGTH 7	/* Node pointer */
 /* Internal management bytes needed to store 2 transid/key on an index page */
 #define MARIA_MAX_PACK_TRANSID_SIZE   (TRANSID_SIZE+1)
 #define MARIA_TRANSID_PACK_OFFSET     (256- TRANSID_SIZE - 1)
 #define MARIA_MIN_TRANSID_PACK_OFFSET (MARIA_TRANSID_PACK_OFFSET-TRANSID_SIZE)
-#define MARIA_INDEX_OVERHEAD_SIZE     (MARIA_MAX_PACK_TRANSID_SIZE * 2)
+#define MARIA_INDEX_OVERHEAD_SIZE     (MARIA_MAX_PACK_TRANSID_SIZE * 2 + \
+                                       MARIA_MAX_POINTER_LENGTH)
 #define MARIA_DELETE_KEY_NR  255	/* keynr for deleted blocks */
 
 /*