937a0e68cb
During a parallel GIN build, each key is serialized into a GinTuple, a transient representation used only while sorting. _gin_build_tuple() lays out the whole tuple (the palloc size, the key memcpy, and the offset of the posting list) from a local variable holding the real key length, but then stored that length in GinTuple.keylen, which was uint16. For a key longer than 65535 bytes, the stored length was thus silently truncated. On read-back, GinTupleGetFirst() and _gin_parse_tuple_items() recompute the posting-list offset from the truncated keylen and land inside the key data, so ginPostingListDecodeAllSegments() decodes garbage: an assertion failure with assertions enabled, and a read past the end of the allocation without, which could in turn lead to a crash or garbage being written into the index. Only parallel builds are affected, because only they materialize a GinTuple; a serial build of the same data succeeds, as index_form_tuple() compresses large keys before the GinMaxItemSize check. To fix, widen GinTuple.keylen to Size, which is what VARSIZE_ANY() returns and what GinBuffer.keylen already uses, and use Size for the local in _gin_build_tuple() too, which was an int that truncated VARSIZE_ANY() the same way. Widening keylen moves GinTuple.data. The key value is accessed in place in data, so data must be MAXALIGN'ed; before, that was only true by accident of the field layout. This branch predates the use of C11 alignas, so force the alignment the way PGAlignedBlock did: put keylen in a union with double and int64 members, which puts data at a MAXALIGN'ed offset on all platforms, including 32-bit ones where Size is 4 bytes and MAXIMUM_ALIGNOF is 8. A static assertion verifies the resulting offset. Bug: #19545 Author: Ewan Young <kdbase.hack@gmail.com> Reported-by: Yuelin Wang <1217816127@qq.com> Reviewed-by: Peter Eisentraut <peter@eisentraut.org> Discussion: https://www.postgresql.org/message-id/flat/19545-0f25b7e47351e8fc%40postgresql.org
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.
Copyright and license information can be found in the file COPYRIGHT.
General documentation about this version of PostgreSQL can be found at https://www.postgresql.org/docs/18/. In particular, information about building PostgreSQL from the source code can be found at https://www.postgresql.org/docs/18/installation.html.
The latest version of this software, and related software, may be obtained at https://www.postgresql.org/download/. For more information look at our web site located at https://www.postgresql.org/.