diff options
author | Lars Knoll <lars.knoll@qt.io> | 2016-11-02 14:10:47 +0100 |
---|---|---|
committer | Giuseppe D'Angelo <giuseppe.dangelo@kdab.com> | 2016-11-11 12:34:27 +0000 |
commit | bfaa8925d5cc0a59cec3f747a8d982ca819f026b (patch) | |
tree | f50e0fde4e197fee070fc2906b16085352b45328 /src/corelib/json | |
parent | 3c2cb87de2554b9c4f6e2080768fe9ede00aeab3 (diff) |
Improve the validation algorithm for binary JSON
Add better boundary checks and catch (hopefully all)
cases where invalid binary JSON could cause crashes.
Change-Id: I206510b7c5e3ba953802a5f46645878e65704ecc
Reviewed-by: Edward Welbourne <edward.welbourne@qt.io>
Diffstat (limited to 'src/corelib/json')
-rw-r--r-- | src/corelib/json/qjson.cpp | 25 | ||||
-rw-r--r-- | src/corelib/json/qjson_p.h | 35 |
2 files changed, 41 insertions, 19 deletions
diff --git a/src/corelib/json/qjson.cpp b/src/corelib/json/qjson.cpp index c3b58e59a5..c6fff068ce 100644 --- a/src/corelib/json/qjson.cpp +++ b/src/corelib/json/qjson.cpp @@ -129,10 +129,12 @@ bool Data::valid() const return false; bool res = false; - if (header->root()->is_object) - res = static_cast<Object *>(header->root())->isValid(); + Base *root = header->root(); + int maxSize = alloc - sizeof(Header); + if (root->is_object) + res = static_cast<Object *>(root)->isValid(maxSize); else - res = static_cast<Array *>(header->root())->isValid(); + res = static_cast<Array *>(root)->isValid(maxSize); return res; } @@ -195,9 +197,9 @@ int Object::indexOf(const QString &key, bool *exists) return min; } -bool Object::isValid() const +bool Object::isValid(int maxSize) const { - if (tableOffset + length*sizeof(offset) > size) + if (size > (uint)maxSize || tableOffset + length*sizeof(offset) > size) return false; QString lastKey; @@ -206,8 +208,7 @@ bool Object::isValid() const if (entryOffset + sizeof(Entry) >= tableOffset) return false; Entry *e = entryAt(i); - int s = e->size(); - if (table()[i] + s > tableOffset) + if (!e->isValid(tableOffset - table()[i])) return false; QString key = e->key(); if (key < lastKey) @@ -221,9 +222,9 @@ bool Object::isValid() const -bool Array::isValid() const +bool Array::isValid(int maxSize) const { - if (tableOffset + length*sizeof(offset) > size) + if (size > (uint)maxSize || tableOffset + length*sizeof(offset) > size) return false; for (uint i = 0; i < length; ++i) { @@ -323,12 +324,12 @@ bool Value::isValid(const Base *b) const int s = usedStorage(b); if (!s) return true; - if (s < 0 || offset + s > (int)b->tableOffset) + if (s < 0 || s > (int)b->tableOffset - offset) return false; if (type == QJsonValue::Array) - return static_cast<Array *>(base(b))->isValid(); + return static_cast<Array *>(base(b))->isValid(s); if (type == QJsonValue::Object) - return static_cast<Object *>(base(b))->isValid(); + return static_cast<Object *>(base(b))->isValid(s); return true; } diff --git a/src/corelib/json/qjson_p.h b/src/corelib/json/qjson_p.h index b7de24d165..c5fd38e640 100644 --- a/src/corelib/json/qjson_p.h +++ b/src/corelib/json/qjson_p.h @@ -302,12 +302,19 @@ public: String(const char *data) { d = (Data *)data; } struct Data { - qle_int length; + qle_uint length; qle_ushort utf16[1]; }; Data *d; + int byteSize() const { return sizeof(uint) + sizeof(ushort) * d->length; } + bool isValid(int maxSize) const { + // Check byteSize() <= maxSize, avoiding integer overflow + maxSize -= sizeof(uint); + return maxSize >= 0 && uint(d->length) <= maxSize / sizeof(ushort); + } + inline String &operator=(const QString &str) { d->length = str.length(); @@ -376,11 +383,16 @@ public: Latin1String(const char *data) { d = (Data *)data; } struct Data { - qle_short length; + qle_ushort length; char latin1[1]; }; Data *d; + int byteSize() const { return sizeof(ushort) + sizeof(char)*(d->length); } + bool isValid(int maxSize) const { + return byteSize() <= maxSize; + } + inline Latin1String &operator=(const QString &str) { int len = d->length = str.length(); @@ -567,7 +579,7 @@ public: } int indexOf(const QString &key, bool *exists); - bool isValid() const; + bool isValid(int maxSize) const; }; @@ -577,7 +589,7 @@ public: inline Value at(int i) const; inline Value &operator [](int i); - bool isValid() const; + bool isValid(int maxSize) const; }; @@ -631,12 +643,12 @@ public: // key // value data follows key - int size() const { + uint size() const { int s = sizeof(Entry); if (value.latinKey) - s += sizeof(ushort) + qFromLittleEndian(*(ushort *) ((const char *)this + sizeof(Entry))); + s += shallowLatin1Key().byteSize(); else - s += sizeof(uint) + sizeof(ushort)*qFromLittleEndian(*(int *) ((const char *)this + sizeof(Entry))); + s += shallowKey().byteSize(); return alignedSize(s); } @@ -662,6 +674,15 @@ public: return shallowKey().toString(); } + bool isValid(int maxSize) const { + if (maxSize < (int)sizeof(Entry)) + return false; + maxSize -= sizeof(Entry); + if (value.latinKey) + return shallowLatin1Key().isValid(maxSize); + return shallowKey().isValid(maxSize); + } + bool operator ==(const QString &key) const; inline bool operator !=(const QString &key) const { return !operator ==(key); } inline bool operator >=(const QString &key) const; |