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Assert name/short_desc to prevent SHOW ALL segfault

Steve Chavez <steve@supabase.io>

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From: Steve Chavez <steve@supabase.io>
To: pgsql-hackers@postgresql.org
Date: 2022-05-24T04:39:16Z
Lists: pgsql-hackers

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Hello hackers,

The DefineCustomStringVariable function(or any
other DefineCustomXXXVariable) has a short_desc parameter that can be
NULL and it's not apparent that this will lead to a segfault when SHOW ALL
is used.
This happens because the ShowAllGUCConfig function expects a non-NULL
short_desc.

This happened for the Supabase supautils extension(
https://github.com/supabase/supautils/issues/24) and any other extension
that uses the DefineCustomXXXVariable has the same bug risk.

This patch does an Assert on the short_desc(also on the name as an extra
measure), so a postgres built with --enable-cassert can prevent the above
issue.

---
Steve Chavez
Engineering at https://supabase.com/

Commits

Same data as JSON: GET /api/v1/messages/:b64id/commits the thread's linked commits as JSON, with link sources. API reference →

  1. Introduce pg_attribute_nonnull(...)

  2. Handle NULL for short descriptions of custom GUC variables