Horton

Re: Regression with large XML data input

Tom Lane <tgl@sss.pgh.pa.us>

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From: Tom Lane <tgl@sss.pgh.pa.us>
To: Michael Paquier <michael@paquier.xyz>
Cc: Robert Treat <rob@xzilla.net>, Jim Jones <jim.jones@uni-muenster.de>, Postgres hackers <pgsql-hackers@lists.postgresql.org>, Erik Wienhold <ewie@ewie.name>
Date: 2025-07-28T02:16:47Z
Lists: pgsql-hackers 
Michael Paquier <michael@paquier.xyz> writes:
> On Fri, Jul 25, 2025 at 02:21:26PM -0400, Tom Lane wrote:
>> However, from Jim Jones' result upthread, a "minor update" of libxml2
>> could also have caused this problem: 2.9.7 and 2.9.14 behave
>> differently.  So we don't have sole control --- or sole responsibility
>> --- here.

> This sentence is incorrect after I have double-checked the behaviors I
> am seeing based on local builds of libxml2 2.9.7 and 2.9.14.

Hmm, okay, I misread Jim's results then.  But there still remains
the big question: what reason is there to believe that it's safe
to return to the old behavior?  If newer libxml2 versions report
XML_ERR_RESOURCE_LIMIT on the same input, doesn't it seem likely
that there's a live hazard in the old code?

			regards, tom lane

Commits

  1. Remove unnecessary complication around xmlParseBalancedChunkMemory.

  2. Avoid regression in the size of XML input that we will accept.

  3. Use xmlParseInNodeContext not xmlParseBalancedChunkMemory.

  4. Revert "Add support for parsing of large XML data (>= 10MB)"