Re: [PATCH 3/8] Add support for a generic wal reading facility dubbed XLogReader

Andres Freund escribió:
> On Monday, October 29, 2012 08:58:53 PM Alvaro Herrera wrote:
> > Heikki Linnakangas escribió:

> > Andres commented elsewhere about reading xlog records, processing them
> > as they came in, and do a running CRC while we're still reading it. I
> > think this is a mistake; we shouldn't do anything with a record until
> > the CRC has been verified. Otherwise we risk reading arbitrarily
> > corrupt data.
>
> Uhm. xlog.c does just the same. It reads the header and if it looks valid it
> uses its length information to read the full record and only computes the CRC
> at the end.

Uh. Correct.

Am I the only one who finds this rather bizarre? Maybe this was okay
when xlog data would only come from WAL files stored in the data
directory at recovery, but if we're now receiving these from a remote
sender over the network I wonder if we should be protecting against
malicious senders. (This is not related to this patch anyway.)

--
Álvaro Herrera http://www.2ndQuadrant.com/
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