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49e29cbe8c
This only affects MEMORY_CONTEXT_CHECKING builds. This fixes an off-by-one issue in GenerationRealloc() where the fast-path code which tries to reuse the existing allocation if the existing chunk is >= the new requested size. The code there thought it was always ok to use the existing chunk, but when oldsize == size there isn't enough space to store the sentinel byte. If both sizes matched exactly set_sentinel() would overwrite the first byte beyond the chunk and then subsequent GenerationRealloc() calls could then fail the Assert(chunk->requested_size < oldsize) check which is trying to ensure the chunk is large enough to store the sentinel. The same issue does not exist in aset.c as the sentinel checking code only adds a sentinel byte if there's enough space in the chunk. Reported-by: Alexander Lakhin <exclusion@gmail.com> Discussion: https://postgr.es/m/49275921-7b39-41af-5eb8-97b50ce3312e@gmail.com Backpatch-through: 16, where the problem was introduced by 0e480385e
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: https://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 https://www.postgresql.org/download/. For more information look at our web site located at https://www.postgresql.org/.