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Fix missing bounds checks on decoded face indices in sequential mesh decoder #1198

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Fix missing bounds checks on decoded face indices in sequential mesh decoder #1198

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21 changes: 19 additions & 2 deletions src/draco/compression/mesh/mesh_sequential_decoder.cc
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Original file line number Diff line number Diff line change
Expand Up @@ -65,7 +65,7 @@ bool MeshSequentialDecoder::DecodeConnectivity() {
return false;
}
if (connectivity_method == 0) {
if (!DecodeAndDecompressIndices(num_faces)) {
if (!DecodeAndDecompressIndices(num_faces, num_points)) {
return false;
}
} else {
Expand All @@ -78,6 +78,9 @@ bool MeshSequentialDecoder::DecodeConnectivity() {
if (!buffer()->Decode(&val)) {
return false;
}
if (val >= num_points) {
return false;
}
face[j] = val;
}
mesh()->AddFace(face);
Expand All @@ -91,6 +94,9 @@ bool MeshSequentialDecoder::DecodeConnectivity() {
if (!buffer()->Decode(&val)) {
return false;
}
if (val >= num_points) {
return false;
}
face[j] = val;
}
mesh()->AddFace(face);
Expand All @@ -105,6 +111,9 @@ bool MeshSequentialDecoder::DecodeConnectivity() {
if (!DecodeVarint(&val, buffer())) {
return false;
}
if (val >= num_points) {
return false;
}
face[j] = val;
}
mesh()->AddFace(face);
Expand All @@ -118,6 +127,9 @@ bool MeshSequentialDecoder::DecodeConnectivity() {
if (!buffer()->Decode(&val)) {
return false;
}
if (val >= num_points) {
return false;
}
face[j] = val;
}
mesh()->AddFace(face);
Expand All @@ -138,7 +150,8 @@ bool MeshSequentialDecoder::CreateAttributesDecoder(int32_t att_decoder_id) {
new LinearSequencer(point_cloud()->num_points())))));
}

bool MeshSequentialDecoder::DecodeAndDecompressIndices(uint32_t num_faces) {
bool MeshSequentialDecoder::DecodeAndDecompressIndices(uint32_t num_faces,
uint32_t num_points) {
// Get decoded indices differences that were encoded with an entropy code.
std::vector<uint32_t> indices_buffer(num_faces * 3);
if (!DecodeSymbols(num_faces * 3, 1, buffer(), indices_buffer.data())) {
Expand Down Expand Up @@ -167,6 +180,10 @@ bool MeshSequentialDecoder::DecodeAndDecompressIndices(uint32_t num_faces) {
}
}
const int32_t index_value = index_diff + last_index_value;
if (index_value < 0 ||
static_cast<uint32_t>(index_value) >= num_points) {
return false;
}
face[j] = index_value;
last_index_value = index_value;
}
Expand Down
3 changes: 2 additions & 1 deletion src/draco/compression/mesh/mesh_sequential_decoder.h
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Original file line number Diff line number Diff line change
Expand Up @@ -30,8 +30,9 @@ class MeshSequentialDecoder : public MeshDecoder {

private:
// Decodes face indices that were compressed with an entropy code.
// |num_points| is used to validate that every decoded index is in range.
// Returns false on error.
bool DecodeAndDecompressIndices(uint32_t num_faces);
bool DecodeAndDecompressIndices(uint32_t num_faces, uint32_t num_points);
};

} // namespace draco
Expand Down