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Avoid crash after function syntax error in a replication worker. 

If a syntax error occurred in a SQL-language or PL/pgSQL-language
CREATE FUNCTION or DO command executed in a logical replication worker,
we'd suffer a null pointer dereference or assertion failure.  That
seems like a rather contrived case, but nonetheless worth fixing.

The cause is that function_parse_error_transpose assumes it must be
executing within the context of a Portal, but logical/worker.c
doesn't create a Portal since it's not running the standard executor.
We can just back off the hard Assert check and make it fail gracefully
if there's not an ActivePortal.  (I have a feeling that the aggressive
check here was my fault originally, probably because I wasn't sure if
the case would always hold and wanted to find out.  Well, now we know.)

The hazard seems to exist in all branches that have logical replication,
so back-patch to v10.

Maxim Orlov, Anton Melnikov, Masahiko Sawada, Tom Lane

Discussion: https://postgr.es/m/b570c367-ba38-95f3-f62d-5f59b9808226@inbox.ru
Discussion: https://postgr.es/m/adf0452f-8c6b-7def-d35e-ab516c80088e@inbox.ru
This commit is contained in:
Tom Lane 2022-11-03 12:01:57 -04:00
parent 19cefebe71
commit 5f3cec77b1
1 changed files with 15 additions and 5 deletions
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20
src/backend/catalog/pg_proc.c
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@ -977,7 +977,6 @@ function_parse_error_transpose(const char *prosrc)
{
int origerrposition;
int newerrposition;
const char *queryText;
/*
* Nothing to do unless we are dealing with a syntax error that has a
@ -995,11 +994,22 @@ function_parse_error_transpose(const char *prosrc)
}
/* We can get the original query text from the active portal (hack...) */
Assert(ActivePortal && ActivePortal->status == PORTAL_ACTIVE);
queryText = ActivePortal->sourceText;
if (ActivePortal && ActivePortal->status == PORTAL_ACTIVE)
{
const char *queryText = ActivePortal->sourceText;
/* Try to locate the prosrc in the original text */
newerrposition = match_prosrc_to_query(prosrc, queryText, origerrposition);
/* Try to locate the prosrc in the original text */
newerrposition = match_prosrc_to_query(prosrc, queryText,
origerrposition);
}
else
{
/*
* Quietly give up if no ActivePortal. This is an unusual situation
* but it can happen in, e.g., logical replication workers.
*/
newerrposition = -1;
}
if (newerrposition > 0)
{