/ 
perl-5.44.0
⭐ Starred 2013 / Test2::Manual::Anatomy::IPC
Security Advisories (1)
CVE-2026-15534 (2026-08-09)

Perl versions through 5.45.1 have out-of-bounds heap reads and writes during regular expression matching via an undersized superlinear cache in S_regmatch. The regex engine's superlinear cache holds one bit per subject position for each participating WHILEM node, so the bit count is the subject length plus one times the number of nodes. Nothing checks that product for positive overflow of the signed 32-bit count: a 286331153 byte subject matched against a pattern with 15 participating nodes stores the count as 14, leaving a two byte cache. The cache is then indexed from the real match position and node number, so reads go past the end of the allocation, and on failure CACHEsayNO sets a bit past it. A caller that matches an attacker controlled subject of this size against a pattern of this shape can crash the process or corrupt heap memory.

NAME

Test2::Manual::Anatomy::IPC - Manual for the IPC system.

DESCRIPTION

This document describes the IPC system.

WHAT IS THE IPC SYSTEM

The IPC system is activated by loading Test2::IPC. This makes hubs process/thread aware, and makes them forward events along to the parent process/thread as necessary.

HOW DOES THE IPC SYSTEM AFFECT EVERYTHING?

Test2::API and Test2::API::Instance have some behaviors that trigger if Test2::IPC is loaded before the global state is initialized. Mainly an IPC driver will be initiated and stored in the global state.

If an IPC driver is initialized then all hubs will be initialized with a reference to the driver instance. If a hub has an IPC driver instance it will use it to forward events to parent processes and threads.

WHAT DOES AN IPC DRIVER DO?

An Test2::IPC::Driver provides a way to send event data to a destination process+thread+hub (or to all globally). The driver must also provide a way for a process/thread/hub to read in any pending events that have been sent to it.

HOW DOES THE DEFAULT IPC DRIVER WORK?

The default IPC driver is Test2::IPC::Driver::Files. This default driver, when initialized, starts by creating a temporary directory. Any time an event needs to be sent to another process/thread/hub, the event will be written to a file using Storable. The file is written with the destination process, thread, and hub as part of the filename. All hubs will regularly check for pending IPC events and will process them.

This driver is further optimized using a small chunk of SHM. Any time a new event is sent via IPC the shm is updated to have a new value. Hubs will not bother checking for new IPC events unless the shm value has changed since their last poll. A result of this is that the IPC system is surprisingly fast, and does not waste time polling the hard drive when there are no pending events.

SEE ALSO

Test2::Manual - Primary index of the manual.

SOURCE

The source code repository for Test2-Manual can be found at https://github.com/Test-More/test-more/.

MAINTAINERS

Chad Granum <exodist@cpan.org>

AUTHORS

Chad Granum <exodist@cpan.org>

COPYRIGHT

Copyright Chad Granum <exodist@cpan.org>.

This program is free software; you can redistribute it and/or modify it under the same terms as Perl itself.

See http://dev.perl.org/licenses/