Thank you for noticing me of that. Is there any way to know how a
bug report has been concluded? Or should I search -hackers for
a corresponding thread?
At Thu, 26 Apr 2018 21:13:48 +0900, Michael Paquier <michael@paquier.xyz> wrote in <20180426121348.GA2365@paquier.xyz>
> On Thu, Apr 26, 2018 at 07:53:04PM +0900, Kyotaro HORIGUCHI wrote:
> > I think this behavior is a bug. XLogReadRecord is considering the
> > case but palloc_extended() breaks it. So in the attached, add a
> > new flag MCXT_ALLOC_NO_PARAMERR to palloc_extended() and
> > allocate_recordbuf calls it with the new flag. That alone fixes
> > the problem. However, the patch frees read state buffer facing
> > errorneous records since such records can leave a too-large
> > buffer allocated.
>
> This problem is already discussed here:
> https://commitfest.postgresql.org/18/1516/
>
> And here is the thread:
> https://www.postgresql.org/message-id/flat/0A3221C70F24FB45833433255569204D1F8B57AD@G01JPEXMBYT05
>
> Tsunakawa-san and I discussed a couple of approaches. Extending
> palloc_extended so as an incorrect length does not result in an error is
> also something that crossed by mind, but the length handling is
> different on the backend and the frontend, so I discarded the idea you
> are proposing here and instead relied on a check with AllocSizeIsValid,
> which gives a more simple patch:
> https://www.postgresql.org/message-id/20180314052753.GA16179%40paquier.xyz
Yeah, perhaps all approaches in the thread came to my mind but
choosed different one. I'm fine with the approach in the thread.
> This got no interest from committers yet unfortunately, but I think that
> this is a real problem which should be back-patched :(
Several other WAL-related fixes are also waiting to be picked up..
regards.
--
Kyotaro Horiguchi
NTT Open Source Software Center