8776faa81c
The way the code was written, the padding was copied from uninitialized memory areas.. Because the structs are local variables in the code where the WAL records are constructed, making them larger and zeroing the padding bytes would not make the code very pretty, so rather than fixing this directly by zeroing out the padding bytes, it seems more clear to not try to align the tuples in the WAL records. The redo functions are taught to copy the tuple header to a local variable to avoid unaligned access. Stable-branches have the same problem, but we can't change the WAL format there, so fix in master only. Reading a few random extra bytes at the stack is harmless in practice, so it's not worth crafting a different back-patchable fix. Per reports from Kevin Grittner and Andres Freund, using clang static analyzer and Valgrind, respectively.
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/.