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Fix cuda overflow #19487

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Merged
lucylq merged 1 commit into from
May 13, 2026
+34 −14
Merged

Fix cuda overflow #19487

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48 changes: 34 additions & 14 deletions backends/aoti/slim/core/slim_tensor.h
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Original file line number Diff line number Diff line change
Expand Up @@ -433,13 +433,19 @@ class SlimTensor {
/**
* Copy data from another tensor to this tensor.
*
* Both tensors must have the same numel and dtype.
* Currently only supports CPU-to-CPU copy (contiguous tensors only).
* Both tensors must have the same numel, sizes and dtype.
*
* @param other The source tensor to copy from
* @return Reference to this tensor
*/
SlimTensor& copy_(const SlimTensor& other) {
ET_CHECK_MSG(
this->dim() == other.dim(),
"copy_: dim of tensors must match (%zu vs %zu)",
this->dim(),
Comment on lines 441 to +445
other.dim());
ET_CHECK_MSG(
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@Gasoonjia Gasoonjia May 12, 2026

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This check also enforces two tensors having same shape -- can we remove it?

this->sizes() == other.sizes(), "copy_: sizes of tensors must match");
ET_CHECK_MSG(
this->numel() == other.numel(), "copy_: numel of tensors must match");
ET_CHECK_MSG(this->dtype() == other.dtype(), "copy_: dtype must match");
Comment on lines +447 to 451
Expand All @@ -463,29 +469,43 @@ class SlimTensor {

std::vector<int64_t> counter(this->dim(), 0);
for (size_t i = 0; i < this->numel(); i++) {
// Compute src offset in elements
int64_t src_offset = 0;
for (size_t d = 0; d < other.dim(); d++) {
src_offset += counter[d] * other.stride(d);
}

// Compute dst offset in elements
int64_t dst_offset = 0;
for (size_t d = 0; d < this->dim(); d++) {
dst_offset += counter[d] * this->stride(d);
int64_t src_term = 0;
int64_t dst_term = 0;
// src_offset = src_offset + counter[d] * other.stride(d)
// dst_offset = dst_offset + counter[d] * this->stride(d)
ET_CHECK_MSG(
!::c10::mul_overflows(counter[d], other.stride(d), &src_term) &&
!::c10::add_overflows(src_offset, src_term, &src_offset) &&
!::c10::mul_overflows(counter[d], this->stride(d), &dst_term) &&
!::c10::add_overflows(dst_offset, dst_term, &dst_offset),
"copy_: offset computation overflow");
}
size_t src_byte_offset = 0;
size_t dst_byte_offset = 0;
// src_byte_offset = src_offset * elem_size
// dst_byte_offset = dst_offset * elem_size
ET_CHECK_MSG(
src_offset >= 0 && dst_offset >= 0 &&
!::c10::mul_overflows(
static_cast<size_t>(src_offset),
elem_size,
&src_byte_offset) &&
!::c10::mul_overflows(
static_cast<size_t>(dst_offset), elem_size, &dst_byte_offset),
"copy_: byte offset overflow");

// Copy elem_size bytes from src to dst
if (this->device().is_cpu() && other.device().is_cpu()) {
std::memcpy(
dst_data + dst_offset * elem_size,
src_data + src_offset * elem_size,
elem_size);
dst_data + dst_byte_offset, src_data + src_byte_offset, elem_size);
} else if (this->device().is_cuda() || other.device().is_cuda()) {
Comment on lines 500 to 504
#if defined(CUDA_AVAILABLE)
DeviceTraits<c10::DeviceType::CUDA>::memcpy(
dst_data + dst_offset * elem_size,
src_data + src_offset * elem_size,
dst_data + dst_byte_offset,
src_data + src_byte_offset,
elem_size,
device(), // dst device
other.device() // src device
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