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ExecEvalCase() tried to save a cycle or two by passing &econtext->caseValue_isNull as the isNull argument to its sub-evaluation of the CASE value expression. If that subexpression itself contained a CASE, then *isNull was an alias for econtext->caseValue_isNull within the recursive call of ExecEvalCase(), leading to confusion about whether the inner call's caseValue was null or not. In the worst case this could lead to a core dump due to dereferencing a null pointer. Fix by not assigning to the global variable until control comes back from the subexpression. Also, avoid using the passed-in isNull pointer transiently for evaluation of WHEN expressions. (Either one of these changes would have been sufficient to fix the known misbehavior, but it's clear now that each of these choices was in itself dangerous coding practice and best avoided. There do not seem to be any similar hazards elsewhere in execQual.c.) Also, it was possible for inlining of a SQL function that implements the equality operator used for a CASE comparison to result in one CASE expression's CaseTestExpr node being inserted inside another CASE expression. This would certainly result in wrong answers since the improperly nested CaseTestExpr would be caused to return the inner CASE's comparison value not the outer's. If the CASE values were of different data types, a crash might result; moreover such situations could be abused to allow disclosure of portions of server memory. To fix, teach inline_function to check for "bare" CaseTestExpr nodes in the arguments of a function to be inlined, and avoid inlining if there are any. Heikki Linnakangas, Michael Paquier, Tom Lane Report: https://github.com/greenplum-db/gpdb/pull/327 Report: <4DDCEEB8.50602@enterprisedb.com> Security: CVE-2016-5423 |
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PostgreSQL Database Management System ===================================== This directory contains the source code distribution of the PostgreSQL database management system. PostgreSQL is an advanced object-relational database management system that supports an extended subset of the SQL standard, including transactions, foreign keys, subqueries, triggers, user-defined types and functions. This distribution also contains C language bindings. PostgreSQL has many language interfaces, many of which are listed here: http://www.postgresql.org/download See the file INSTALL for instructions on how to build and install PostgreSQL. That file also lists supported operating systems and hardware platforms and contains information regarding any other software packages that are required to build or run the PostgreSQL system. Copyright and license information can be found in the file COPYRIGHT. A comprehensive documentation set is included in this distribution; it can be read as described in the installation instructions. The latest version of this software may be obtained at http://www.postgresql.org/download/. For more information look at our web site located at http://www.postgresql.org/.