[jira] [Created] (TRAFODION-3243) Dereference of deallocated NAString in UPDATE STATISTICS can cause cores

["David Wayne Birdsall (JIRA)" <ji...@apache.org>]

David Wayne Birdsall created TRAFODION-3243:
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             Summary: Dereference of deallocated NAString in UPDATE STATISTICS can cause cores
                 Key: TRAFODION-3243
                 URL: https://issues.apache.org/jira/browse/TRAFODION-3243
             Project: Apache Trafodion
          Issue Type: Bug
          Components: sql-cmp
    Affects Versions: 2.3, 2.4
            Reporter: David Wayne Birdsall
            Assignee: David Wayne Birdsall


In ustat/hs_globals.cpp, the HSColGroupStruct destructor deletes the colNames member (an NAString), then calls HSColGroupStruct::freeISMemory. If logging is on (which is the default nowadays), the latter method dereferences colNames, calling its data() method. NAString :: data() adds a null terminator to the end of its string; in a deleted NAString, this can result in the corruption of a heap boundary tag. This seems to only happen in the case where the original string did not fit into the small_ buffer of the NAString (which happens when column names are sufficiently long, e.g. multi-column histograms) and then only rarely.

The fix is to defer deleting colNames until after freeISMemory is called.



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