When an UPDATE statement triggers check_foreign_key() with the
action set to "cascade", it generates more UPDATE statements to
modify the key values in referencing relations. If a new key value
is NULL, SPI_getvalue() returns a NULL pointer, which is
subsequently passed to quote_literal_cstr(), causing a segfault.
To fix, skip quoting when a new key value is NULL and insert an
unquoted NULL keyword instead.
Oversight in commit 260e97733b. While the refint documentation
recommends marking primary key columns NOT NULL, the aforementioned
scenario accidentally worked on platforms where snprintf()
substitutes "(null)" for NULL pointers. Note that for
character-type columns, the old code quoted "(null)" as a string
literal, so this didn't always produce correct results. But it
still seems better to fix this than to reject cases that previously
worked.
Reported-by: Nikita Kalinin <n.kalinin@postgrespro.ru>
Author: Ayush Tiwari <ayushtiwari.slg01@gmail.com>
Reviewed-by: Pierre Forstmann <pierre.forstmann@gmail.com>
Discussion: https://postgr.es/m/19476-bd04ea6241345303%40postgresql.org
Backpatch-through: 14
The PostgreSQL contrib tree
---------------------------
This subtree contains porting tools, analysis utilities, and plug-in
features that are not part of the core PostgreSQL system, mainly
because they address a limited audience or are too experimental to be
part of the main source tree. This does not preclude their
usefulness.
User documentation for each module appears in the main SGML
documentation.
When building from the source distribution, these modules are not
built automatically, unless you build the "world" target. You can
also build and install them all by running "make all" and "make
install" in this directory; or to build and install just one selected
module, do the same in that module's subdirectory.
Some directories supply new user-defined functions, operators, or
types. To make use of one of these modules, after you have installed
the code you need to register the new SQL objects in the database
system by executing a CREATE EXTENSION command. In a fresh database,
you can simply do
CREATE EXTENSION module_name;
See the PostgreSQL documentation for more information about this
procedure.
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