[jira] [Created] (ORC-586) [C++] Memory leak in StructColumnReader

["Zoltán Borók-Nagy (Jira)" <ji...@apache.org>]

Zoltán Borók-Nagy created ORC-586:
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             Summary: [C++] Memory leak in StructColumnReader
                 Key: ORC-586
                 URL: https://issues.apache.org/jira/browse/ORC-586
             Project: ORC
          Issue Type: Bug
            Reporter: Zoltán Borók-Nagy


StructColumnReader can leak memory if its constructor throws an exception.

StructColumnReader has a member vector<ColumnReader*> called 'children' which is filled in the constructor:

[https://github.com/apache/orc/blob/c26ff4c351d7c34c4272442a6874703f510282a8/c%2B%2B/src/ColumnReader.cc#L874]

 
{noformat}
      for(unsigned int i=0; i < type.getSubtypeCount(); ++i) {        const Type& child = *type.getSubtype(i);        if (selectedColumns[static_cast<uint64_t>(child.getColumnId())]) {          children.push_back(buildReader(child, stripe).release());        }      }

{noformat}
buildReader() returns a unique_ptr, but the constructor calls release() on it which returns the underlying raw pointer and in the meantime the unique_ptr releases the ownership.

StructColumnReader's destructor is supposed to invoke delete on these raw pointers, but if an exception is thrown during the construction of a StructColumnReader, then only the destructors of the member variables are called. Therefore the vector gets destroyed, but the ColumnReader objects are leaked.

The solution is to store unique_ptrs in the vector instead of raw pointers.

 



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