Fix potential heap use after free in CSVRow::iterator

Author: vincentlaucsb

include/internal/csv_row.cpp

@@ -203,7 +203,7 @@ namespace csv {
 
     CSV_INLINE HEDLEY_NON_NULL(2)
     CSVRow::iterator::iterator(const CSVRow* _reader, int _i)
-        : daddy(_reader), i(_i) {
+        : daddy(_reader), data(_reader->data), i(_i) {
         if (_i < (int)this->daddy->size())
             this->field = std::make_shared<CSVField>(
                 this->daddy->operator[](_i));

include/internal/csv_row.hpp

@@ -267,9 +267,10 @@ namespace csv {
 #endif
 
         private:
-            const CSVRow * daddy = nullptr;            // Pointer to parent
-            std::shared_ptr<CSVField> field = nullptr; // Current field pointed at
-            int i = 0;                                 // Index of current field
+            const CSVRow * daddy = nullptr;                      // Pointer to parent
+            internals::RawCSVDataPtr data = nullptr;             // Keep data alive for lifetime of iterator
+            std::shared_ptr<CSVField> field = nullptr;           // Current field pointed at
+            int i = 0;                                           // Index of current field
         };
 
         /** A reverse iterator over the contents of a CSVRow. */