Feedback-ID: i0fe9450f:Fastmail
Date: Wed, 9 Jul 2025 09:45:07 +0900
From: Michael Paquier <michael@paquier.xyz>
To: Tom Lane <tgl@sss.pgh.pa.us>
Cc: Robin Haberkorn <haberkorn@b1-systems.de>,
	Jim Jones <jim.jones@uni-muenster.de>,
	pgsql-bugs@lists.postgresql.org, maralist86@mail.ru
Subject: Re: BUG #18943: Return value of a function 'xmlBufferCreate' is
 dereferenced at xpath.c:177 without checking for NUL
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On Tue, Jul 08, 2025 at 09:36:37AM -0400, Tom Lane wrote:
> The comment in xml_errorHandler() argues

Yep.

> So switching to _ALL (or even _WELL_FORMED) mode would result in
> nontrivial differences in the behavior of xpath.c's functions with
> bad input.  Maybe that's a reasonable thing to do, but it's a
> question of user-visible behavior not just code cleanliness.

Yes, I don't see a huge advantage in doing the switch for this module.
If the gain in information in the error states grabbed from libxml2
makes it a win, that may be a different argument (I am fine to be
proved wrong), but I cannot get excited about that without more
data to claim it so.

I have quickly tested the change, and the xpath_string() path was one
area that immediately stood out, and we may report an incorrect error.
--
Michael

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