| From: | Peter Geoghegan <pg(at)bowt(dot)ie> |
|---|---|
| To: | Alexander Lakhin <exclusion(at)gmail(dot)com> |
| Cc: | Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>, pgsql-bugs(at)lists(dot)postgresql(dot)org, Richard Guo <guofenglinux(at)gmail(dot)com>, Andres Freund <andres(at)anarazel(dot)de> |
| Subject: | Re: BUG #17798: Incorrect memory access occurs when using BEFORE ROW UPDATE trigger |
| Date: | 2023-04-30 20:39:37 |
| Message-ID: | CAH2-Wzm3aQznsDrVu10C3hcvez8qwdy2578Hw4BgwXLWZ1NDQw@mail.gmail.com |
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| Lists: | pgsql-bugs |
On Sun, Apr 30, 2023 at 5:00 AM Alexander Lakhin <exclusion(at)gmail(dot)com> wrote:
> Yeah, also the environment changed since 86dc90056, so I couldn't just revert
> that commit to test the ExecFilterJunk() behavior on master.
>
> All the questions you raised require a more thorough investigation.
Are you aware of the fact that Valgrind has custom instrumentation
that makes it directly capable of detecting access to no-longer-pinned
buffers? See commits 7b7ed046 and 1e0dfd16.
I think that that may be a factor here. If it is, then it's a little
surprising that you ever found the problem with ASAN, since of course
we don't have custom ASAN instrumentation that tells ASAN things like
"until I say otherwise, it is not okay to read from this range of
memory, which is this backend's memory mapping for an individual
shared buffer that was just unpinned".
--
Peter Geoghegan
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