BUG#912510: Crash in do_copy_not_null with semijoin=ON, firstmatch=ON, aggregate ...

- Create/use do_copy_nullable_row_to_notnull() function for ref access, which is used 
  when copying from not-NULL field in table that can be NULL-complemented to not-NULL field.

1 files changed, 28 insertions, 1 deletions

diff --git a/sql/field_conv.cc b/sql/field_conv.cc
index ce914f7b368..ed910c4ef70 100644
--- a/sql/field_conv.cc
+++ b/sql/field_conv.cc
@@ -248,6 +248,25 @@ static void do_outer_field_null(Copy_field *copy)
   }
 }
 
+/*
+  Copy: (not-NULL field in table that can be NULL-complemented) -> (not-NULL
+  field)
+*/
+static void do_copy_nullable_row_to_notnull(Copy_field *copy)
+{
+  if (*copy->null_row ||
+      (copy->from_null_ptr && (*copy->from_null_ptr & copy->from_bit)))
+  {
+    copy->to_field->set_warning(MYSQL_ERROR::WARN_LEVEL_WARN,
+                                WARN_DATA_TRUNCATED, 1);
+    copy->to_field->reset();
+  }
+  else
+  {
+    (copy->do_copy2)(copy);
+  }
+
+}
 
 /* Copy: (NULL-able field) -> (not NULL-able field) */
 static void do_copy_not_null(Copy_field *copy)
@@ -638,7 +657,15 @@ void Copy_field::set(Field *to,Field *from,bool save)
       else if (to_field == to_field->table->next_number_field)
         do_copy= do_copy_next_number;
       else
-        do_copy= do_copy_not_null;
+      {
+        if (!from_null_ptr)
+        {
+          null_row= &from->table->null_row;
+          do_copy= do_copy_nullable_row_to_notnull;
+        }
+        else
+          do_copy= do_copy_not_null;
+      }
     }
   }
   else if (to_field->real_maybe_null())