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Fix heap-buffer-overflow in glTF decoder accessor reads #1165

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Fix heap-buffer-overflow in glTF decoder accessor reads #1165

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80 changes: 71 additions & 9 deletions src/draco/io/gltf_decoder.cc
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Original file line number Diff line number Diff line change
Expand Up @@ -160,14 +160,33 @@ StatusOr<std::vector<uint32_t>> CopyDataAsUint32(

const tinygltf::Buffer &buffer = model.buffers[buffer_view.buffer];

const uint8_t *const data_start =
buffer.data.data() + buffer_view.byteOffset + accessor.byteOffset;
const int byte_stride = accessor.ByteStride(buffer_view);
const int component_size =
tinygltf::GetComponentSizeInBytes(accessor.componentType);
const int num_components =
TinyGltfUtils::GetNumComponentsForType(accessor.type);
const int num_elements = accessor.count * num_components;

// Validate that accessor data fits within the buffer.
const size_t start_offset =
static_cast<size_t>(buffer_view.byteOffset) + accessor.byteOffset;
if (accessor.count <= 0 || component_size <= 0 || num_components <= 0 ||
byte_stride <= 0) {
return Status(Status::DRACO_ERROR,
"Invalid accessor or buffer view parameters.");
}
const size_t last_element_end =
start_offset +
static_cast<size_t>(accessor.count - 1) * byte_stride +
static_cast<size_t>(num_components) * component_size;
if (last_element_end > buffer.data.size()) {
return Status(Status::DRACO_ERROR,
"Accessor data exceeds buffer bounds.");
}

const uint8_t *const data_start = buffer.data.data() + start_offset;

const size_t num_elements =
static_cast<size_t>(accessor.count) * num_components;

std::vector<uint32_t> output;
output.resize(num_elements);
Expand Down Expand Up @@ -225,17 +244,34 @@ StatusOr<std::vector<TypeT>> CopyDataAs(const tinygltf::Model &model,

const tinygltf::Buffer &buffer = model.buffers[buffer_view.buffer];

const uint8_t *const data_start =
buffer.data.data() + buffer_view.byteOffset + accessor.byteOffset;
const int byte_stride = accessor.ByteStride(buffer_view);
const int component_size =
tinygltf::GetComponentSizeInBytes(accessor.componentType);
const int num_components =
TinyGltfUtils::GetNumComponentsForType(accessor.type);

// Validate that accessor data fits within the buffer.
const size_t start_offset =
static_cast<size_t>(buffer_view.byteOffset) + accessor.byteOffset;
if (accessor.count <= 0 || component_size <= 0 || num_components <= 0 ||
byte_stride <= 0) {
return Status(Status::DRACO_ERROR,
"Invalid accessor or buffer view parameters.");
}
const size_t last_element_end =
start_offset +
static_cast<size_t>(accessor.count - 1) * byte_stride +
static_cast<size_t>(num_components) * component_size;
if (last_element_end > buffer.data.size()) {
return Status(Status::DRACO_ERROR,
"Accessor data exceeds buffer bounds.");
}

const uint8_t *const data_start = buffer.data.data() + start_offset;

std::vector<TypeT> output;
output.resize(accessor.count);

const int num_components =
TinyGltfUtils::GetNumComponentsForType(accessor.type);
int out_index = 0;
const uint8_t *data = data_start;
for (int i = 0; i < accessor.count; ++i) {
Expand Down Expand Up @@ -273,12 +309,29 @@ StatusOr<std::vector<TypeT>> CopyDataAs(const tinygltf::Model &model,

const tinygltf::Buffer &buffer = model.buffers[buffer_view.buffer];

const uint8_t *const data_start =
buffer.data.data() + buffer_view.byteOffset + accessor.byteOffset;
const int byte_stride = accessor.ByteStride(buffer_view);
const int component_size =
tinygltf::GetComponentSizeInBytes(accessor.componentType);

// Validate that accessor data fits within the buffer.
const size_t start_offset =
static_cast<size_t>(buffer_view.byteOffset) + accessor.byteOffset;
if (accessor.count <= 0 || component_size <= 0 || num_components <= 0 ||
byte_stride <= 0) {
return Status(Status::DRACO_ERROR,
"Invalid accessor or buffer view parameters.");
}
const size_t last_element_end =
start_offset +
static_cast<size_t>(accessor.count - 1) * byte_stride +
static_cast<size_t>(num_components) * component_size;
if (last_element_end > buffer.data.size()) {
return Status(Status::DRACO_ERROR,
"Accessor data exceeds buffer bounds.");
}

const uint8_t *const data_start = buffer.data.data() + start_offset;

std::vector<TypeT> output;
output.resize(accessor.count);

Expand Down Expand Up @@ -310,6 +363,15 @@ Status CopyDataFromBufferView(const tinygltf::Model &model, int buffer_view_id,
}

const tinygltf::Buffer &buffer = model.buffers[buffer_view.buffer];

// Validate that buffer view data fits within the buffer.
const size_t end_offset =
static_cast<size_t>(buffer_view.byteOffset) + buffer_view.byteLength;
if (end_offset > buffer.data.size()) {
return ErrorStatus(
"Buffer view byteOffset + byteLength exceeds buffer size.");
}

const uint8_t *const data_start = buffer.data.data() + buffer_view.byteOffset;

data->resize(buffer_view.byteLength);
Expand Down
23 changes: 20 additions & 3 deletions src/draco/io/tiny_gltf_utils.h
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Original file line number Diff line number Diff line change
Expand Up @@ -101,16 +101,33 @@ class TinyGltfUtils {

const tinygltf::Buffer &buffer = model.buffers[buffer_view.buffer];

const unsigned char *const data_start =
buffer.data.data() + buffer_view.byteOffset + accessor.byteOffset;
const int byte_stride = accessor.ByteStride(buffer_view);
const int component_size =
tinygltf::GetComponentSizeInBytes(accessor.componentType);
const int num_components = GetNumComponentsForType(accessor.type);

// Validate that accessor data fits within the buffer.
const size_t start_offset =
static_cast<size_t>(buffer_view.byteOffset) + accessor.byteOffset;
if (accessor.count <= 0 || component_size <= 0 || num_components <= 0 ||
byte_stride <= 0) {
return Status(Status::DRACO_ERROR,
"Invalid accessor or buffer view parameters.");
}
const size_t last_element_end =
start_offset +
static_cast<size_t>(accessor.count - 1) * byte_stride +
static_cast<size_t>(num_components) * component_size;
if (last_element_end > buffer.data.size()) {
return Status(Status::DRACO_ERROR,
"Accessor data exceeds buffer bounds.");
}

const unsigned char *const data_start = buffer.data.data() + start_offset;

std::vector<T> output;
output.resize(accessor.count);

const int num_components = GetNumComponentsForType(accessor.type);
const unsigned char *data = data_start;
for (int i = 0; i < accessor.count; ++i) {
T values;
Expand Down