Re: BUG #15448: server process (PID 22656) was terminated by exception 0xC0000005

From: Andrew Dunstan <andrew(dot)dunstan(at)2ndquadrant(dot)com>
To: Amit Langote <Langote_Amit_f8(at)lab(dot)ntt(dot)co(dot)jp>, tillmann73(at)yahoo(dot)de, pgsql-bugs(at)lists(dot)postgresql(dot)org, PostgreSQL-development <pgsql-hackers(at)postgresql(dot)org>
Subject: Re: BUG #15448: server process (PID 22656) was terminated by exception 0xC0000005
Date: 2018-10-23 11:46:01
Message-ID: ad2162e6-38ef-76cb-0638-c90f8b00a0d6@2ndQuadrant.com
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On 10/22/2018 10:00 PM, Amit Langote wrote:
>
> After observing the test case in the provided log, I managed to reproduce
> it with the following:
>
> create table foo (a int primary key, b int);
> create table bar (a int references foo on delete cascade, b int);
> insert into foo values (1, 1);
> insert into foo values (2, 2);
> alter table foo add c int;
> alter table foo drop c;
> delete from foo;
> server closed the connection unexpectedly
> This probably means the server terminated abnormally
> before or while processing the request.
> The connection to the server was lost. Attempting reset: Failed.
>
> Analyzing this crash, I located the bug down to GetTupleForTrigger(), but
> perhaps it's really in heap_expand_tuple() / expand_tuple(), where the
> value of trigger tuple's t_self is being switched from a valid one to an
> invalid value.
>
> In heaptuple.c: expand_tuple()
>
>
> ItemPointerSetInvalid(&((*targetHeapTuple)->t_self));
>
>
> FWIW, attached patch fixes this for me. Adding Andrew whose recent commit
> 7636e5c60f [1] seems to have introduced the heap_expan_tuple call in
> GetTupleForTrigger. Maybe, he can better judge a fix for this.
>

Thanks. I think the line in expand_tuple is a thinko and we should
change it, rather than change GetTupleForTrigger().

Here is a patch that does that and also adds your test case to the
regression tests.

cheers

andrew

--
Andrew Dunstan https://www.2ndQuadrant.com
PostgreSQL Development, 24x7 Support, Remote DBA, Training & Services

Attachment Content-Type Size
fast_default_expand_tuple_fix.patch text/x-patch 2.2 KB

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