User PerfektesChaos from dewiki has wrote a example lua module, which produces a fatal in the php preprocessor.

The module is:

• Cause a server crash.
• includes/parser/Preprocessor_DOM.php line 1692:
• "Call to a member function item() on a non-object"
• Crashes any 1.24wmf1 wiki, not only beta.wmflabs.org

local p = { }

function p.f( frame )

local story = "ö"                  -- non-ASCII char
local sub   = story:sub( 1, 1 )    -- ASCII substring at half of UTF-8
                                   -- should have been mw.ustring.sub()
return frame:callParserFunction( "#tag:nowiki", { sub } )

end -- p.f

return p

The error is:
includes/parser/Preprocessor_DOM.php line 1692: "Call to a member function item() on a non-object"

I have run it with warnings on on my dev machine and the output is:
Warning: DOMDocument::loadXML() [domdocument.loadxml]: Input is not proper UTF-8, indicate encoding ! Bytes: 0xC3 0x3C 0x2F 0x76 in Entity, line: 1 in \includes\parser\Preprocessor_DOM.php on line 85

Notice: Trying to get property of non-object in \includes\parser\Preprocessor_DOM.php on line 88

Fatal error: Call to a member function item() on a non-object in \includes\parser\Preprocessor_DOM.php on line 1692

See http://de.wikipedia.beta.wmflabs.org/wiki/MakeTheServerCrash for more information and a link to the example page.

Looks like the half byte is mangeled into the builded xml in the preprocessor and than it gives a invalid xml.

Version: 1.24rc
Severity: normal