Thread

Commits

Fix variable initialization with ALTER SUBSCRIPTION DROP PUBLICATION
- 79718c1c6c00 14.0 landed
Put option listing back into alphabetical order
- 3af10943ce21 14.0 cited

Fix uninitialized copy_data var (src/backend/commands/subscriptioncmds.c)

Ranier Vilela <ranier.vf@gmail.com> — 2021-06-23T17:38:26Z

Hi,

Not per Coverity!

About comments:
1. For drop, no "copy data"
2. Only refresh the added/*dropped* list of publications. (my emphasis)

The documentation says:
https://www.postgresql.org/docs/14/sql-altersubscription.html

"DROP PUBLICATION *publication_name*

Changes the list of subscribed publications. SET replaces the entire list
of publications with a new list, ADD adds additional publications, DROP
removes publications from the list of publications. See CREATE SUBSCRIPTION
<https://www.postgresql.org/docs/14/sql-createsubscription.html> for more
information. By default, this command will also act like REFRESH PUBLICATION,
except that in case of ADD or DROP, only the added or dropped publications
are refreshed.

*set_publication_option* specifies additional options for this operation.
The supported options are:
refresh (boolean)

When false, the command will not try to refresh table information. REFRESH
PUBLICATION should then be executed separately. The default is true.

Additionally, refresh options as described under REFRESH PUBLICATION may be
specified."
So, is allowed DROP PUBLICATION with (refresh = true)

I try some tests with subscription.sql:
CREATE SUBSCRIPTION regress_testsub3 CONNECTION
'dbname=regress_doesnotexist' PUBLICATION testpub WITH (connect = false,
streaming = true);
+CREATE SUBSCRIPTION regress_testsub3 CONNECTION
'dbname=regress_doesnotexist' PUBLICATION testpub WITH (connect = false,
streaming = true);
+WARNING:  tables were not subscribed, you will have to run ALTER
SUBSCRIPTION ... REFRESH PUBLICATION to subscribe the tables

ALTER SUBSCRIPTION regress_testsub3 ENABLE;
ALTER SUBSCRIPTION regress_testsub3 REFRESH PUBLICATION;
+ALTER SUBSCRIPTION regress_testsub3 ENABLE;
+ALTER SUBSCRIPTION regress_testsub3 REFRESH PUBLICATION;
+ERROR:  could not connect to the publisher: connection to server at
"localhost" (::1), port 58080 failed: FATAL:  database
"regress_doesnotexist" does not exist

-- ok - delete active publication with refresh = true
ALTER SUBSCRIPTION regress_testsub3 DROP PUBLICATION testpub WITH (refresh
= true);
+-- ok - delete active publication with refresh = true
+ALTER SUBSCRIPTION regress_testsub3 DROP PUBLICATION testpub WITH (refresh
= true);
+ERROR:  subscription must contain at least one publication

I think this bug is live, for lack of tests with DROP PUBLICATION WITH
(refresh = true).

regards,
Ranier Vilela

Re: Fix uninitialized copy_data var (src/backend/commands/subscriptioncmds.c)

Ranier Vilela <ranier.vf@gmail.com> — 2021-06-25T13:55:21Z

Em qua., 23 de jun. de 2021 às 14:38, Ranier Vilela <ranier.vf@gmail.com>
escreveu:

> Hi,
>
> Not per Coverity!
>
> About comments:
> 1. For drop, no "copy data"
> 2. Only refresh the added/*dropped* list of publications. (my emphasis)
>
> The documentation says:
> https://www.postgresql.org/docs/14/sql-altersubscription.html
>
> "DROP PUBLICATION *publication_name*
>
> Changes the list of subscribed publications. SET replaces the entire list
> of publications with a new list, ADD adds additional publications, DROP
> removes publications from the list of publications. See CREATE
> SUBSCRIPTION
> <https://www.postgresql.org/docs/14/sql-createsubscription.html> for more
> information. By default, this command will also act like REFRESH
> PUBLICATION, except that in case of ADD or DROP, only the added or
> dropped publications are refreshed.
>
> *set_publication_option* specifies additional options for this operation.
> The supported options are:
> refresh (boolean)
>
> When false, the command will not try to refresh table information. REFRESH
> PUBLICATION should then be executed separately. The default is true.
>
> Additionally, refresh options as described under REFRESH PUBLICATION may
> be specified."
> So, is allowed DROP PUBLICATION with (refresh = true)
>
> I try some tests with subscription.sql:
> CREATE SUBSCRIPTION regress_testsub3 CONNECTION
> 'dbname=regress_doesnotexist' PUBLICATION testpub WITH (connect = false,
> streaming = true);
> +CREATE SUBSCRIPTION regress_testsub3 CONNECTION
> 'dbname=regress_doesnotexist' PUBLICATION testpub WITH (connect = false,
> streaming = true);
> +WARNING:  tables were not subscribed, you will have to run ALTER
> SUBSCRIPTION ... REFRESH PUBLICATION to subscribe the tables
>
> ALTER SUBSCRIPTION regress_testsub3 ENABLE;
> ALTER SUBSCRIPTION regress_testsub3 REFRESH PUBLICATION;
> +ALTER SUBSCRIPTION regress_testsub3 ENABLE;
> +ALTER SUBSCRIPTION regress_testsub3 REFRESH PUBLICATION;
> +ERROR:  could not connect to the publisher: connection to server at
> "localhost" (::1), port 58080 failed: FATAL:  database
> "regress_doesnotexist" does not exist
>
> -- ok - delete active publication with refresh = true
> ALTER SUBSCRIPTION regress_testsub3 DROP PUBLICATION testpub WITH (refresh
> = true);
> +-- ok - delete active publication with refresh = true
> +ALTER SUBSCRIPTION regress_testsub3 DROP PUBLICATION testpub WITH
> (refresh = true);
> +ERROR:  subscription must contain at least one publication
>
> I think this bug is live, for lack of tests with DROP PUBLICATION WITH
> (refresh = true).
>
https://github.com/postgres/postgres/commit/3af10943ce21450e299b3915b9cad47cd90369e9
fixes some issues with subscriptioncmds.c, but IMHO still lack this issue.

regards,
Ranier Vilela

Re: Fix uninitialized copy_data var (src/backend/commands/subscriptioncmds.c)

Peter Smith <smithpb2250@gmail.com> — 2021-06-28T00:17:55Z

On Fri, Jun 25, 2021 at 11:55 PM Ranier Vilela <ranier.vf@gmail.com> wrote:
>
>
> https://github.com/postgres/postgres/commit/3af10943ce21450e299b3915b9cad47cd90369e9
> fixes some issues with subscriptioncmds.c, but IMHO still lack this issue.
>

I have not tested this, and gcc gave no warnings about it, but just by
visual code inspection I do agree with you that this looks like a
problem, even in the latest code.

IIUC for the case ALTER_SUBSCRIPTION_DROP_PUBLICATION it looks like
the uninitialized copy_data local stack var would remain uninitialized
(undefined) still at the time it is passed at
AlterSubscription_refresh(sub, copy_data);

------
Kind Regards,
Peter Smith.
Fujitsu Australia.

Re: Fix uninitialized copy_data var (src/backend/commands/subscriptioncmds.c)

Michael Paquier <michael@paquier.xyz> — 2021-06-28T03:29:06Z

On Mon, Jun 28, 2021 at 10:17:55AM +1000, Peter Smith wrote:
> IIUC for the case ALTER_SUBSCRIPTION_DROP_PUBLICATION it looks like
> the uninitialized copy_data local stack var would remain uninitialized
> (undefined) still at the time it is passed at
> AlterSubscription_refresh(sub, copy_data);

Yes, that's wrong.  AlterSubscription_refresh() would happily look at
this uninitialized value when performing a refresh with this command.
That's the only code path using parse_subscription_options() with this
pattern.  Applied on HEAD.
--
Michael

Re: Fix uninitialized copy_data var (src/backend/commands/subscriptioncmds.c)

Ranier Vilela <ranier.vf@gmail.com> — 2021-06-28T11:05:37Z

Em dom., 27 de jun. de 2021 às 21:18, Peter Smith <smithpb2250@gmail.com>
escreveu:

> On Fri, Jun 25, 2021 at 11:55 PM Ranier Vilela <ranier.vf@gmail.com>
> wrote:
> >
> >
> >
> https://github.com/postgres/postgres/commit/3af10943ce21450e299b3915b9cad47cd90369e9
> > fixes some issues with subscriptioncmds.c, but IMHO still lack this
> issue.
> >
>
> I have not tested this, and gcc gave no warnings about it, but just by
> visual code inspection I do agree with you that this looks like a
> problem, even in the latest code.
>
> IIUC for the case ALTER_SUBSCRIPTION_DROP_PUBLICATION it looks like
> the uninitialized copy_data local stack var would remain uninitialized
> (undefined) still at the time it is passed at
> AlterSubscription_refresh(sub, copy_data);
>
Thanks Peter, for the review.

regards,
Ranier Vilela

Re: Fix uninitialized copy_data var (src/backend/commands/subscriptioncmds.c)

Ranier Vilela <ranier.vf@gmail.com> — 2021-06-28T11:08:54Z

Em seg., 28 de jun. de 2021 às 00:29, Michael Paquier <michael@paquier.xyz>
escreveu:

> On Mon, Jun 28, 2021 at 10:17:55AM +1000, Peter Smith wrote:
> > IIUC for the case ALTER_SUBSCRIPTION_DROP_PUBLICATION it looks like
> > the uninitialized copy_data local stack var would remain uninitialized
> > (undefined) still at the time it is passed at
> > AlterSubscription_refresh(sub, copy_data);
>
> Yes, that's wrong.  AlterSubscription_refresh() would happily look at
> this uninitialized value when performing a refresh with this command.
> That's the only code path using parse_subscription_options() with this
> pattern.  Applied on HEAD.
>
Hi Michael,
Thank you for this comitt.

regards,
Ranier Vilela