From a8ed1cd03bf524072d13c66ab14da8ff1b22cde2 Mon Sep 17 00:00:00 2001 From: Robert Loehning Date: Mon, 13 Jul 2020 20:53:11 +0200 Subject: Fix stack overflow in dtor of QSvgTinyDocument Add a maximum to how many unfinished elements will be parsed by QSvgHandler. Fixes: oss-fuzz-24000 Change-Id: I4cea0500d2bc503d2c509d091300dd1117170299 Reviewed-by: Volker Hilsheimer (cherry picked from commit 2fc2cb44b275c7c18c2db262eec443eb198b9cc6) Reviewed-by: Qt Cherry-pick Bot --- src/svg/qsvghandler.cpp | 11 ++++++++++- 1 file changed, 10 insertions(+), 1 deletion(-) diff --git a/src/svg/qsvghandler.cpp b/src/svg/qsvghandler.cpp index 14f7905..ab5f9ef 100644 --- a/src/svg/qsvghandler.cpp +++ b/src/svg/qsvghandler.cpp @@ -3633,6 +3633,10 @@ void QSvgHandler::init() parse(); } +// Having too many unfinished elements will cause a stack overflow +// in the dtor of QSvgTinyDocument, see oss-fuzz issue 24000. +static const int unfinishedElementsLimit = 2048; + void QSvgHandler::parse() { xml->setNamespaceProcessing(false); @@ -3641,6 +3645,7 @@ void QSvgHandler::parse() m_inStyle = false; #endif bool done = false; + int remainingUnfinishedElements = unfinishedElementsLimit; while (!xml->atEnd() && !done) { switch (xml->readNext()) { case QXmlStreamReader::StartElement: @@ -3652,7 +3657,10 @@ void QSvgHandler::parse() // namespaceUri is empty. The only possible strategy at // this point is to do what everyone else seems to do and // ignore the reported namespaceUri completely. - if (!startElement(xml->name().toString(), xml->attributes())) { + if (remainingUnfinishedElements + && startElement(xml->name().toString(), xml->attributes())) { + --remainingUnfinishedElements; + } else { delete m_doc; m_doc = 0; return; @@ -3660,6 +3668,7 @@ void QSvgHandler::parse() break; case QXmlStreamReader::EndElement: endElement(xml->name()); + ++remainingUnfinishedElements; // if we are using somebody else's qxmlstreamreader // we should not read until the end of the stream done = !m_ownsReader && (xml->name() == QLatin1String("svg")); -- cgit v1.2.1