From: Bossart, Nathan <bossartn@amazon.com>
To: Michael Paquier <michael@paquier.xyz>
To: Andres Freund <andres@anarazel.de>
Cc: pgsql-hackers@lists.postgresql.org <pgsql-hackers@lists.postgresql.org>
Cc: Robert Haas <robertmhaas@gmail.com>
Cc: Schneider, Jeremy <schnjere@amazon.com>
Cc: PostgreSQL-development <pgsql-hackers@postgresql.org>
Cc: Albin, Lloyd P <lalbin@scharp.org>
Subject: Re: BUG #15182: Canceling authentication due to timeout aka Denial of Service Attack
Date: Thu, 26 Jul 2018 15:40:07 +0000
Message-ID: <082C3D70-C39D-41F4-B889-C128D09DE02E@amazon.com> (raw)
In-Reply-To: <E5CF1BFB-322D-41AE-ACFC-237730A9E110@amazon.com>
References: <152512087100.19803.12733865831237526317@wrigleys.postgresql.org>
<9145334b-9583-124c-012e-7d58039ad417@amazon.com>
<CA+TgmobgJ9b0LpwhcCdj_gMDgp9UKmR_1pfX6WpWxGGGVrOG7A@mail.gmail.com>
<20180724041403.GF4035@paquier.xyz>
<F4D1FB53-AAFB-4605-9336-F37A762A7738@anarazel.de>
<20180724045010.GA4736@paquier.xyz>
<B8A865D7-DDD0-4E04-9077-02C76B206FF5@anarazel.de>
<20180726052415.GC3927@paquier.xyz>
<E5CF1BFB-322D-41AE-ACFC-237730A9E110@amazon.com>
On 7/26/18, 10:07 AM, "Bossart, Nathan" <bossartn@amazon.com> wrote:
> The first time we use this callback, the relation won't be locked, so
> isn't it possible that we won't get a valid tuple here? I did notice
> that callbacks like RangeVarCallbackForRenameRule,
> RangeVarCallbackForPolicy, and RangeVarCallbackForRenameTrigger assume
> that the relation can be concurrently dropped, but
> RangeVarCallbackOwnsRelation does not. Instead, we assume that the
> syscache search will succeed if the given OID is valid. Is this a
> bug, or am I missing something?
Please pardon the noise. I see that we don't accept invalidation
messages until later on in RangeVarGetRelidExtended(), at which point
we'll retry and get InvalidOid for concurrently dropped relations.
Nathan
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To: pgsql-bugs@postgresql.org
Cc: bossartn@amazon.com, michael@paquier.xyz, andres@anarazel.de, pgsql-hackers@lists.postgresql.org, robertmhaas@gmail.com, schnjere@amazon.com, pgsql-hackers@postgresql.org, lalbin@scharp.org
Subject: Re: BUG #15182: Canceling authentication due to timeout aka Denial of Service Attack
In-Reply-To: <082C3D70-C39D-41F4-B889-C128D09DE02E@amazon.com>
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