Re: PostmasterContext survives into parallel workers!? - Mailing list pgsql-hackers

From Robert Haas
Subject Re: PostmasterContext survives into parallel workers!?
Date
Msg-id CA+TgmoYZ7LB5erAQ7AbigruWhcHoqxhvfYOF1mVxU-XT7rs+FA@mail.gmail.com
Whole thread Raw
In response to PostmasterContext survives into parallel workers!?  (Tom Lane <tgl@sss.pgh.pa.us>)
Responses Re: PostmasterContext survives into parallel workers!?  (Tom Lane <tgl@sss.pgh.pa.us>)
Re: PostmasterContext survives into parallel workers!?  (Andres Freund <andres@anarazel.de>)
Re: PostmasterContext survives into parallel workers!?  (Tom Lane <tgl@sss.pgh.pa.us>)
List pgsql-hackers
On Mon, Aug 1, 2016 at 4:18 PM, Tom Lane <tgl@sss.pgh.pa.us> wrote:
> I noticed $subject while fooling around with the tqueue.c memory leak
> issues.  This does not seem like a good idea to me.  At the very least,
> it's a waste of space that could be used for something else, and at the
> worst, it might be a security issue because it leaves security-sensitive
> pg_hba and pg_ident information laying about in places where it might be
> recoverable (if only through memory-disclosure bugs, which we've had
> before and no doubt will have again).
>
> The reason is that the parallel worker launch path contains no equivalent
> of PostgresMain's stanza
>
>         if (PostmasterContext)
>         {
>                 MemoryContextDelete(PostmasterContext);
>                 PostmasterContext = NULL;
>         }
>
> Now, I'm undecided whether to flush that context only in parallel workers,
> or to try to make it go away for all bgworkers of any stripe.  The latter
> seems a little better from a security standpoint, but I wonder if anyone
> has a use-case where that'd be a bad idea?

I think it would be better to get rid of it in all bgworkers.

(Also vaguely on the list of things to clean up: can't we make it so
that bgworkers aren't launched from inside a signal handler?  Blech.)

-- 
Robert Haas
EnterpriseDB: http://www.enterprisedb.com
The Enterprise PostgreSQL Company



pgsql-hackers by date:

Previous
From: Tom Lane
Date:
Subject: Re: HandleParallelMessages contains CHECK_FOR_INTERRUPTS?
Next
From: Robert Haas
Date:
Subject: Re: TODO item: Implement Boyer-Moore searching in LIKE queries