Bug#13556000: CHECK AND REPAIR TABLE SHOULD BE MORE ROBUST[2]

Problem description: Corrupt key file for the table. Size of the 
key is greater than the maximum specified size. This results in 
the overflow of the key buffer while reading the key from key 
file.

Fix: If size of key is greater than the maximum size it returns 
an error before writing it into the key buffer. Gives error as 
corrupt file but no stack overflow.

storage/myisam/mi_search.c

@@ -945,9 +945,7 @@ uint _mi_get_binary_pack_key(register MI_KEYDEF *keyinfo, uint nod_flag,
                  ("Found too long binary packed key: %u of %u at 0x%lx",
                   length, keyinfo->maxlength, (long) *page_pos));
       DBUG_DUMP("key", *page_pos, 16);
-      mi_print_error(keyinfo->share, HA_ERR_CRASHED);
-      my_errno=HA_ERR_CRASHED;
-      DBUG_RETURN(0);                                 /* Wrong key */
+      goto crashed;                                  /* Wrong key */
     }
     /* Key is packed against prev key, take prefix from prev key. */
     from= key;
@@ -990,6 +988,8 @@ uint _mi_get_binary_pack_key(register MI_KEYDEF *keyinfo, uint nod_flag,
         if (from == from_end) { from=page;  from_end=page_end; }
         length+= (uint) ((*key++ = *from++));
       }
+      if (length > keyseg->length)
+        goto crashed;
     }
     else
       length=keyseg->length;
@@ -1029,15 +1029,18 @@ uint _mi_get_binary_pack_key(register MI_KEYDEF *keyinfo, uint nod_flag,
     if (from_end != page_end)
     {
       DBUG_PRINT("error",("Error when unpacking key"));
-      mi_print_error(keyinfo->share, HA_ERR_CRASHED);
-      my_errno=HA_ERR_CRASHED;
-      DBUG_RETURN(0);                                 /* Error */
+      goto crashed;                                 /* Error */
     }
     /* Copy data pointer and, if appropriate, key block pointer. */
     memcpy((uchar*) key,(uchar*) from,(size_t) length);
     *page_pos= from+length;
   }
   DBUG_RETURN((uint) (key-start_key)+keyseg->length);
+
+  crashed:
+    mi_print_error(keyinfo->share, HA_ERR_CRASHED);
+    my_errno= HA_ERR_CRASHED;
+    DBUG_RETURN(0);
 }