Horton

Re: [PATCH] Fix segmentation fault and infinite loop in jsonb_{plperl,plpython}

Aleksander Alekseev <aleksander@tigerdata.com>

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From: Aleksander Alekseev <aleksander@tigerdata.com>
To: PostgreSQL Hackers <pgsql-hackers@lists.postgresql.org>
Cc: Tom Lane <tgl@sss.pgh.pa.us>
Date: 2026-06-16T21:25:18Z
Lists: pgsql-hackers 
Hi,

> > Alternatively I could implement a check for the loops, if you feel
> > like this is worth the effort.
>
> I thought about that, but I'm not sure how to build a bulletproof
> check at reasonable (ie, near zero) cost.  We could detect the example
> case where an object refers directly to itself, by noticing that "in"
> doesn't change in one iteration.  But I'm pretty sure it's possible to
> build reference loops involving two or more Perl objects, and those
> would fool such a check.

I was thinking about depth-first search where we store our current
path in a set. If the visited node is already in the set then the
graph has loops.

This is not exactly cheap but the complexity is proportional to the
cost of the serialization so I think we should be fine. The good thing
is that the user will get a sensible error message instead of an
infinite loop.

-- 
Best regards,
Aleksander Alekseev

Commits

  1. hstore_plperl: Add CHECK_FOR_INTERRUPTS() in reference-unwinding loop.

  2. jsonb_plperl, jsonb_plpython: Fix unguarded recursion and loops.