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Fix floating-point exception in Zstd::Decompress #254

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Merged
JieyangChen7 merged 1 commit into from
Feb 5, 2026
Merged

Fix floating-point exception in Zstd::Decompress #254

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16 changes: 14 additions & 2 deletions include/mgard-x/Lossless/Zstd.hpp
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Original file line number Diff line number Diff line change
Expand Up @@ -111,7 +111,19 @@ template <typename DeviceType> class Zstd {

uint32_t actual_out_count = 0;
actual_out_count = *reinterpret_cast<const size_t *>(in_data);
Resize(actual_out_count, compressionLevel, queue_idx);

// FIX: Only resize out_data if needed, do not touch in_data which contains
// the compressed data we just copied. The original code called Resize()
// which would free and reallocate BOTH in_data and out_data, destroying
// the compressed data when actual_out_count > buffer_size.
if (this->buffer_size < actual_out_count) {
size_t const estimated_out_size = ZSTD_compressBound(actual_out_count);
if (out_data != nullptr) {
MemoryManager<DeviceType>::FreeHost(out_data, queue_idx);
}
MemoryManager<DeviceType>::MallocHost(
out_data, estimated_out_size + sizeof(size_t), queue_idx);
}
DeviceRuntime<DeviceType>::SyncQueue(queue_idx);

ZSTD_decompress(out_data, actual_out_count, in_data + sizeof(size_t),
Expand All @@ -137,4 +149,4 @@ template <typename DeviceType> class Zstd {

} // namespace mgard_x

#endif
#endif
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