parent
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commit
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@ -0,0 +1,284 @@
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From 6326bec46a618c72feba4a2bb994c4d475050aed Mon Sep 17 00:00:00 2001
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From: Ahmad Samir <a.samirh78@gmail.com>
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Date: Thu, 22 Jun 2023 15:56:07 +0300
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Subject: [PATCH] QXmlStreamReader: make fastScanName() indicate parsing status to callers
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This fixes a crash while parsing an XML file with garbage data, the file
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starts with '<' then garbage data:
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- The loop in the parse() keeps iterating until it hits "case 262:",
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which calls fastScanName()
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- fastScanName() iterates over the text buffer scanning for the
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attribute name (e.g. "xml:lang"), until it finds ':'
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- Consider a Value val, fastScanName() is called on it, it would set
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val.prefix to a number > val.len, then it would hit the 4096 condition
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and return (returned 0, now it returns the equivalent of
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std::null_opt), which means that val.len doesn't get modified, making
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it smaller than val.prefix
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- The code would try constructing an XmlStringRef with negative length,
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which would hit an assert in one of QStringView's constructors
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Add an assert to the XmlStringRef constructor.
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Add unittest based on the file from the bug report.
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Later on I will replace FastScanNameResult with std::optional<qsizetype>
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(std::optional is C++17, which isn't required by Qt 5.15, and we want to
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backport this fix).
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Credit to OSS-Fuzz.
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Fixes: QTBUG-109781
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Fixes: QTBUG-114829
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Pick-to: 6.6 6.5 6.2 5.15
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Change-Id: I455a5eeb47870c2ac9ffd0cbcdcd99c1ae2dd374
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Reviewed-by: Allan Sandfeld Jensen <allan.jensen@qt.io>
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---
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diff --git a/src/corelib/serialization/qxmlstream.cpp b/src/corelib/serialization/qxmlstream.cpp
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index b76243c176..adb57a0239 100644
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--- a/src/corelib/serialization/qxmlstream.cpp
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+++ b/src/corelib/serialization/qxmlstream.cpp
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@@ -1243,7 +1243,10 @@ inline qsizetype QXmlStreamReaderPrivate::fastScanContentCharList()
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return n;
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}
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-inline qsizetype QXmlStreamReaderPrivate::fastScanName(qint16 *prefix)
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+// Fast scan an XML attribute name (e.g. "xml:lang").
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+inline QXmlStreamReaderPrivate::FastScanNameResult
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+QXmlStreamReaderPrivate::fastScanName(Value *val)
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+
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{
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qsizetype n = 0;
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uint c;
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@@ -1251,7 +1254,8 @@ inline qsizetype QXmlStreamReaderPrivate::fastScanName(qint16 *prefix)
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if (n >= 4096) {
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// This is too long to be a sensible name, and
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// can exhaust memory, or the range of decltype(*prefix)
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- return 0;
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+ raiseNamePrefixTooLongError();
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+ return {};
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}
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switch (c) {
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case '\n':
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@@ -1280,23 +1284,24 @@ inline qsizetype QXmlStreamReaderPrivate::fastScanName(qint16 *prefix)
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case '+':
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case '*':
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putChar(c);
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- if (prefix && *prefix == n+1) {
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- *prefix = 0;
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+ if (val && val->prefix == n + 1) {
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+ val->prefix = 0;
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+
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putChar(':');
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--n;
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}
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- return n;
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+ return FastScanNameResult(n);
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case ':':
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- if (prefix) {
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- if (*prefix == 0) {
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- *prefix = qint16(n + 2);
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+ if (val) {
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+ if (val->prefix == 0) {
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+ val->prefix = n + 2;
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} else { // only one colon allowed according to the namespace spec.
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putChar(c);
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- return n;
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+ return FastScanNameResult(n);
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}
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} else {
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putChar(c);
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- return n;
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+ return FastScanNameResult(n);
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}
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Q_FALLTHROUGH();
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default:
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@@ -1305,12 +1310,13 @@ inline qsizetype QXmlStreamReaderPrivate::fastScanName(qint16 *prefix)
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}
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}
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- if (prefix)
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- *prefix = 0;
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+ if (val)
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+ val->prefix = 0;
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+
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qsizetype pos = textBuffer.size() - n;
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putString(textBuffer, pos);
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textBuffer.resize(pos);
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- return 0;
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+ return FastScanNameResult(0);
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}
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enum NameChar { NameBeginning, NameNotBeginning, NotName };
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@@ -1791,6 +1797,14 @@ void QXmlStreamReaderPrivate::raiseWellFormedError(const QString &message)
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raiseError(QXmlStreamReader::NotWellFormedError, message);
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}
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+void QXmlStreamReaderPrivate::raiseNamePrefixTooLongError()
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+{
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+ // TODO: add a ImplementationLimitsExceededError and use it instead
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+ raiseError(QXmlStreamReader::NotWellFormedError,
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+ QXmlStream::tr("Length of XML attribute name exceeds implemnetation limits (4KiB "
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+ "characters)."));
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+}
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+
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void QXmlStreamReaderPrivate::parseError()
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{
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diff --git a/src/corelib/serialization/qxmlstream.g b/src/corelib/serialization/qxmlstream.g
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index d06c371eb8..fc122e6681 100644
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--- a/src/corelib/serialization/qxmlstream.g
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+++ b/src/corelib/serialization/qxmlstream.g
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@@ -1419,7 +1419,12 @@ space_opt ::= space;
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qname ::= LETTER;
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/.
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case $rule_number: {
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- sym(1).len += fastScanName(&sym(1).prefix);
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+ Value &val = sym(1);
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+ if (auto res = fastScanName(&val))
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+ val.len += *res;
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+ else
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+ return false;
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+
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if (atEnd) {
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resume($rule_number);
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return false;
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@@ -1430,7 +1435,11 @@ qname ::= LETTER;
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name ::= LETTER;
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/.
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case $rule_number:
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- sym(1).len += fastScanName();
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+ if (auto res = fastScanName())
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+ sym(1).len += *res;
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+ else
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+ return false;
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+
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if (atEnd) {
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resume($rule_number);
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return false;
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diff --git a/src/corelib/serialization/qxmlstream_p.h b/src/corelib/serialization/qxmlstream_p.h
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index 1fd69a2c1f..fba6aeb496 100644
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--- a/src/corelib/serialization/qxmlstream_p.h
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+++ b/src/corelib/serialization/qxmlstream_p.h
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@@ -38,7 +38,7 @@ public:
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constexpr XmlStringRef() = default;
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constexpr inline XmlStringRef(const QString *string, qsizetype pos, qsizetype length)
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- : m_string(string), m_pos(pos), m_size(length)
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+ : m_string(string), m_pos(pos), m_size((Q_ASSERT(length >= 0), length))
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{
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}
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XmlStringRef(const QString *string)
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@@ -471,7 +471,16 @@ public:
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qsizetype fastScanLiteralContent();
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qsizetype fastScanSpace();
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qsizetype fastScanContentCharList();
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- qsizetype fastScanName(qint16 *prefix = nullptr);
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+
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+ struct FastScanNameResult {
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+ FastScanNameResult() : ok(false) {}
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+ explicit FastScanNameResult(qsizetype len) : addToLen(len), ok(true) { }
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+ operator bool() { return ok; }
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+ qsizetype operator*() { Q_ASSERT(ok); return addToLen; }
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+ qsizetype addToLen;
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+ bool ok;
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+ };
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+ FastScanNameResult fastScanName(Value *val = nullptr);
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inline qsizetype fastScanNMTOKEN();
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@@ -480,6 +489,7 @@ public:
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void raiseError(QXmlStreamReader::Error error, const QString& message = QString());
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void raiseWellFormedError(const QString &message);
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+ void raiseNamePrefixTooLongError();
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QXmlStreamEntityResolver *entityResolver;
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diff --git a/src/corelib/serialization/qxmlstreamparser_p.h b/src/corelib/serialization/qxmlstreamparser_p.h
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index e3ae6faa44..afd83381b3 100644
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--- a/src/corelib/serialization/qxmlstreamparser_p.h
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+++ b/src/corelib/serialization/qxmlstreamparser_p.h
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@@ -947,7 +947,12 @@ bool QXmlStreamReaderPrivate::parse()
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break;
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case 262: {
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- sym(1).len += fastScanName(&sym(1).prefix);
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+ Value &val = sym(1);
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+ if (auto res = fastScanName(&val))
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+ val.len += *res;
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+ else
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+ return false;
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+
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if (atEnd) {
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resume(262);
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return false;
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@@ -955,7 +960,11 @@ bool QXmlStreamReaderPrivate::parse()
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} break;
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case 263:
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- sym(1).len += fastScanName();
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+ if (auto res = fastScanName())
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+ sym(1).len += *res;
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+ else
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+ return false;
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+
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if (atEnd) {
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resume(263);
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return false;
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diff --git a/tests/auto/corelib/serialization/qxmlstream/tst_qxmlstream.cpp b/tests/auto/corelib/serialization/qxmlstream/tst_qxmlstream.cpp
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index 2799e7a999..7eb0aac5cc 100644
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--- a/tests/auto/corelib/serialization/qxmlstream/tst_qxmlstream.cpp
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+++ b/tests/auto/corelib/serialization/qxmlstream/tst_qxmlstream.cpp
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@@ -581,6 +581,8 @@ private slots:
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void readBack() const;
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void roundTrip() const;
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void roundTrip_data() const;
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+ void test_fastScanName_data() const;
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+ void test_fastScanName() const;
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void entityExpansionLimit() const;
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@@ -1753,5 +1755,42 @@ void tst_QXmlStream::roundTrip() const
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QCOMPARE(out, in);
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}
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+void tst_QXmlStream::test_fastScanName_data() const
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+{
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+ QTest::addColumn<QByteArray>("data");
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+ QTest::addColumn<QXmlStreamReader::Error>("errorType");
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+
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+ // 4096 is the limit in QXmlStreamReaderPrivate::fastScanName()
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+
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+ QByteArray arr = "<a"_ba + ":" + QByteArray("b").repeated(4096 - 1);
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+ QTest::newRow("data1") << arr << QXmlStreamReader::PrematureEndOfDocumentError;
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+
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+ arr = "<a"_ba + ":" + QByteArray("b").repeated(4096);
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+ QTest::newRow("data2") << arr << QXmlStreamReader::NotWellFormedError;
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+
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+ arr = "<"_ba + QByteArray("a").repeated(4000) + ":" + QByteArray("b").repeated(96);
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+ QTest::newRow("data3") << arr << QXmlStreamReader::PrematureEndOfDocumentError;
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+
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+ arr = "<"_ba + QByteArray("a").repeated(4000) + ":" + QByteArray("b").repeated(96 + 1);
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+ QTest::newRow("data4") << arr << QXmlStreamReader::NotWellFormedError;
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+
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+ arr = "<"_ba + QByteArray("a").repeated(4000 + 1) + ":" + QByteArray("b").repeated(96);
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+ QTest::newRow("data5") << arr << QXmlStreamReader::NotWellFormedError;
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+}
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+
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+void tst_QXmlStream::test_fastScanName() const
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+{
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+ QFETCH(QByteArray, data);
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+ QFETCH(QXmlStreamReader::Error, errorType);
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+
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+ QXmlStreamReader reader(data);
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+ QXmlStreamReader::TokenType tokenType;
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+ while (!reader.atEnd())
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+ tokenType = reader.readNext();
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+
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+ QCOMPARE(tokenType, QXmlStreamReader::Invalid);
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+ QCOMPARE(reader.error(), errorType);
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+}
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+
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#include "tst_qxmlstream.moc"
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// vim: et:ts=4:sw=4:sts=4
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