CBOR support: prevent overflowing QByteArray's max allocation

QByteArray doesn't like it.

Apply the same protection to QString, which we know uses the same
backend but uses elements twice as big. That means it can contain
slightly more than half as many elements, but exact half will suffice
for our needs.

Change-Id: Iaa63461109844e978376fffd15f9d4c7a9137856
Reviewed-by: Edward Welbourne <edward.welbourne@qt.io>

1 files changed, 134 insertions, 0 deletions

diff --git a/tests/auto/corelib/serialization/cborlargedatavalidation.cpp b/tests/auto/corelib/serialization/cborlargedatavalidation.cpp
new file mode 100644
index 0000000000..9abfe0f575
--- /dev/null
+++ b/tests/auto/corelib/serialization/cborlargedatavalidation.cpp
@@ -0,0 +1,134 @@
+/****************************************************************************
+**
+** Copyright (C) 2020 Intel Corporation.
+** Contact: https://www.qt.io/licensing/
+**
+** This file is part of the QtCore module of the Qt Toolkit.
+**
+** $QT_BEGIN_LICENSE:LGPL$
+** Commercial License Usage
+** Licensees holding valid commercial Qt licenses may use this file in
+** accordance with the commercial license agreement provided with the
+** Software or, alternatively, in accordance with the terms contained in
+** a written agreement between you and The Qt Company. For licensing terms
+** and conditions see https://www.qt.io/terms-conditions. For further
+** information use the contact form at https://www.qt.io/contact-us.
+**
+** GNU Lesser General Public License Usage
+** Alternatively, this file may be used under the terms of the GNU Lesser
+** General Public License version 3 as published by the Free Software
+** Foundation and appearing in the file LICENSE.LGPL3 included in the
+** packaging of this file. Please review the following information to
+** ensure the GNU Lesser General Public License version 3 requirements
+** will be met: https://www.gnu.org/licenses/lgpl-3.0.html.
+**
+** GNU General Public License Usage
+** Alternatively, this file may be used under the terms of the GNU
+** General Public License version 2.0 or (at your option) the GNU General
+** Public license version 3 or any later version approved by the KDE Free
+** Qt Foundation. The licenses are as published by the Free Software
+** Foundation and appearing in the file LICENSE.GPL2 and LICENSE.GPL3
+** included in the packaging of this file. Please review the following
+** information to ensure the GNU General Public License requirements will
+** be met: https://www.gnu.org/licenses/gpl-2.0.html and
+** https://www.gnu.org/licenses/gpl-3.0.html.
+**
+** $QT_END_LICENSE$
+**
+****************************************************************************/
+
+#include <QtTest/QtTest>
+#include <cbor.h>
+
+namespace {
+// A QIODevice that supplies a fixed header followed by a large sequence of
+// null bytes up until a pre-determined size.
+class LargeIODevice final : public QIODevice
+{
+public:
+    qint64 realSize;
+    QByteArray start;
+
+    LargeIODevice(const QByteArray &start, qint64 size, QObject *parent = nullptr)
+        : QIODevice(parent), realSize(size), start(start)
+    {}
+
+    qint64 size() const override { return realSize; }
+    bool isSequential() const override { return false; }
+
+protected:
+    qint64 readData(char *data, qint64 maxlen) override;
+    qint64 writeData(const char *, qint64) override { return -1; }
+};
+};
+
+qint64 LargeIODevice::readData(char *data, qint64 maxlen)
+{
+    qint64 p = pos();
+    if (maxlen > realSize - p)
+        maxlen = realSize - p;
+    memset(data, '\0', maxlen);
+
+    qint64 fromstart = start.size() - p;
+    if (fromstart > maxlen)
+        fromstart = maxlen;
+    else if (fromstart < 0)
+        fromstart = 0;
+    if (fromstart)
+        memcpy(data, start.constData() + p, fromstart);
+    return maxlen;
+}
+
+void addValidationLargeData(qsizetype minInvalid, qsizetype maxInvalid)
+{
+    char toolong[2 + sizeof(qsizetype)] = { char(0x81) };
+    for (qsizetype v = maxInvalid; v >= minInvalid; --v) {
+        // 0x5a for 32-bit, 0x5b for 64-bit
+        toolong[1] = sizeof(v) > 4 ? 0x5b : 0x5a;
+        qToBigEndian(v, toolong + 2);
+
+        QTest::addRow("bytearray-too-big-for-qbytearray-%llx", v)
+                << QByteArray(toolong, sizeof(toolong)) << 0 << CborErrorDataTooLarge;
+        toolong[1] |= 0x20;
+
+        // QCborStreamReader::readString copies to a QByteArray first
+        QTest::addRow("string-too-big-for-qbytearray-%llx", v)
+                << QByteArray(toolong, sizeof(toolong)) << 0 << CborErrorDataTooLarge;
+    }
+}
+
+void addValidationHugeDevice(qsizetype byteArrayInvalid, qsizetype stringInvalid)
+{
+    qRegisterMetaType<QSharedPointer<QIODevice>>();
+    QTest::addColumn<QSharedPointer<QIODevice>>("device");
+    QTest::addColumn<CborError>("expectedError");
+
+    char buf[1 + sizeof(quint64)];
+    auto device = [&buf](QCborStreamReader::Type t, quint64 size) {
+        buf[0] = quint8(t) | 0x1b;
+        qToBigEndian(size, buf + 1);
+        size += sizeof(buf);
+        QSharedPointer<QIODevice> p =
+                QSharedPointer<LargeIODevice>::create(QByteArray(buf, sizeof(buf)), size);
+        return p;
+    };
+
+    // do the exact limits
+    QTest::newRow("bytearray-just-too-big")
+            << device(QCborStreamReader::ByteArray, byteArrayInvalid) << CborErrorDataTooLarge;
+    QTest::newRow("string-just-too-big")
+            << device(QCborStreamReader::String, stringInvalid) << CborErrorDataTooLarge;
+
+    auto addSize = [=](const char *sizename, qint64 size) {
+        if (byteArrayInvalid < size)
+            QTest::addRow("bytearray-%s", sizename)
+                << device(QCborStreamReader::ByteArray, size) << CborErrorDataTooLarge;
+        if (stringInvalid < size)
+            QTest::addRow("string-%s", sizename)
+                << device(QCborStreamReader::String, size) << CborErrorDataTooLarge;
+    };
+    addSize("1GB", quint64(1) << 30);
+    addSize("2GB", quint64(1) << 31);
+    addSize("4GB", quint64(1) << 32);
+    addSize("max", std::numeric_limits<qint64>::max() - sizeof(buf));
+}