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42b320abe3
Commit a83586b554 decided to scribble on the caller's fcinfo but failed
to take into account that const arguments are written once at expression
init and assumed never to change.
The use_json_null branch overwrote fcinfo->args[2] with a jsonb null
built in the per-tuple expression context. In later rows,
args[2].isnull is still false and args[2].value still holds that
pointer, but the per-tuple context has been reset. Later rows find
args[2].isnull = false, short-circuit past the NULL handling at the top
of the function, and jump straight to jsonb_set with the stale pointer
regardless of their own null_value_treatment argument, which is never
read.
To fix, call jsonb_set through its own call frame instead. Arguments 0,
1 and 3 were already checked non-NULL above, so we can use
DirectFunctionCall4.
Add regression tests covering use_json_null followed by delete_key and
return_target, and a multi-row default-treatment query.
Reported-by: Evan Si <evsi@amazon.com>
Discussion: https://postgr.es/m/CANWCAZY-PS=ev8TiiV1j=NoR2xLopEL8fDq0fyQZahHiP5b+Pw@mail.gmail.com
Backpatch-through: 14
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/.