From f24bd1b8183ec9cc4e239dc560072d3896ec61a1 Mon Sep 17 00:00:00 2001 From: =?UTF-8?q?J=C3=BCri=20Valdmann?= Date: Tue, 8 May 2018 15:30:37 +0200 Subject: QJsonDocument: Avoid overflow of string lengths MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit The added test case contains the binary JSON equivalent of ["ΕΎ"] with the modification that the string's length has been set to INT_MAX. In Value::usedStorage this length is used through the pointer d like so s = sizeof(int) + sizeof(ushort) * qFromLittleEndian(*(int *)d); Because 2 * INT_MAX is UINT_MAX-1, the expression as a whole evaluates to 2, which is considered a valid storage size. However, when converting this binary JSON into ordinary JSON we will attempt to construct a QString of length INT_MAX. Fixed by using String::isValid instead of Value::usedStorage. This method already takes care to avoid the overflow problem. Additionally, I've tried in this patch to clarify the behavior of Value::isValid a bit by writing it in a style that is hopefully more amenable to structural induction. Finally, the test case added in my previous patch had the wrong file extension and is renamed in this one. Task-number: QTBUG-61969 Change-Id: I45d891f2467a71d8d105822ef7eb1a73c3efa67a Reviewed-by: Thiago Macieira (cherry picked from commit 8e47474baf06b3884e9173302395dd25fc09eba9) Reviewed-by: Lars Knoll --- src/corelib/json/qjson.cpp | 43 ++++++++++----------- tests/auto/corelib/json/invalidBinaryData/40.bjson | Bin 0 -> 60 bytes tests/auto/corelib/json/invalidBinaryData/40.json | Bin 60 -> 0 bytes tests/auto/corelib/json/invalidBinaryData/41.bjson | Bin 0 -> 32 bytes 4 files changed, 20 insertions(+), 23 deletions(-) create mode 100644 tests/auto/corelib/json/invalidBinaryData/40.bjson delete mode 100644 tests/auto/corelib/json/invalidBinaryData/40.json create mode 100644 tests/auto/corelib/json/invalidBinaryData/41.bjson diff --git a/src/corelib/json/qjson.cpp b/src/corelib/json/qjson.cpp index 944c7695c6..31260ef5fd 100644 --- a/src/corelib/json/qjson.cpp +++ b/src/corelib/json/qjson.cpp @@ -333,38 +333,35 @@ int Value::usedStorage(const Base *b) const return alignedSize(s); } +inline bool isValidValueOffset(uint offset, uint tableOffset) +{ + return offset >= sizeof(Base) + && offset + sizeof(uint) <= tableOffset; +} + bool Value::isValid(const Base *b) const { - int offset = -1; switch (type) { + case QJsonValue::Null: + case QJsonValue::Bool: + return true; case QJsonValue::Double: - if (latinOrIntValue) - break; - Q_FALLTHROUGH(); + return latinOrIntValue || isValidValueOffset(value, b->tableOffset); case QJsonValue::String: + if (!isValidValueOffset(value, b->tableOffset)) + return false; + if (latinOrIntValue) + return asLatin1String(b).isValid(b->tableOffset - value); + return asString(b).isValid(b->tableOffset - value); case QJsonValue::Array: + return isValidValueOffset(value, b->tableOffset) + && static_cast(base(b))->isValid(b->tableOffset - value); case QJsonValue::Object: - offset = value; - break; - case QJsonValue::Null: - case QJsonValue::Bool: + return isValidValueOffset(value, b->tableOffset) + && static_cast(base(b))->isValid(b->tableOffset - value); default: - break; - } - - if (offset == -1) - return true; - if (offset + sizeof(uint) > b->tableOffset || offset < (int)sizeof(Base)) - return false; - - int s = usedStorage(b); - if (s < 0 || s > (int)b->tableOffset - offset) return false; - if (type == QJsonValue::Array) - return static_cast(base(b))->isValid(s); - if (type == QJsonValue::Object) - return static_cast(base(b))->isValid(s); - return true; + } } /*! diff --git a/tests/auto/corelib/json/invalidBinaryData/40.bjson b/tests/auto/corelib/json/invalidBinaryData/40.bjson new file mode 100644 index 0000000000..277096f8cb Binary files /dev/null and b/tests/auto/corelib/json/invalidBinaryData/40.bjson differ diff --git a/tests/auto/corelib/json/invalidBinaryData/40.json b/tests/auto/corelib/json/invalidBinaryData/40.json deleted file mode 100644 index 277096f8cb..0000000000 Binary files a/tests/auto/corelib/json/invalidBinaryData/40.json and /dev/null differ diff --git a/tests/auto/corelib/json/invalidBinaryData/41.bjson b/tests/auto/corelib/json/invalidBinaryData/41.bjson new file mode 100644 index 0000000000..0b5940ab95 Binary files /dev/null and b/tests/auto/corelib/json/invalidBinaryData/41.bjson differ -- cgit v1.2.3