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webgpu: Fix buffer overflow in BufferManager::Upload causing data corruption #27948

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Merged
guschmue merged 3 commits into from
Apr 8, 2026
Merged

webgpu: Fix buffer overflow in BufferManager::Upload causing data corruption #27948

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f6208df
[WebGPU EP] Fix buffer overflow in BufferManager::Upload causing data…
qjia7 Apr 2, 2026
6fd326e
Merge branch 'main' into fix/webgpu-upload-buffer-overflow
qjia7 Apr 7, 2026
f73de83
Remove ineffective zero-padding in upload staging buffer
qjia7 Apr 8, 2026
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24 changes: 17 additions & 7 deletions onnxruntime/core/providers/webgpu/buffer_manager.cc
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Original file line number Diff line number Diff line change
Expand Up @@ -13,6 +13,11 @@ constexpr size_t NormalizeBufferSize(size_t size) {
return (size + 15) / 16 * 16;
}

// WebGPU requires that the copy size in CopyBufferToBuffer must be a multiple of 4 bytes.
constexpr size_t NormalizeCopySize(size_t size) {
return (size + 3) / 4 * 4;
}

void EnforceBufferUnmapped(WebGpuContext& context, WGPUBuffer buffer) {
if (context.ValidationMode() > ValidationMode::Basic) {
ORT_ENFORCE(wgpuBufferGetMapState(buffer) == WGPUBufferMapState_Unmapped, "Buffer is still mapped.");
Expand Down Expand Up @@ -450,21 +455,26 @@ void BufferManager::Upload(void* src, WGPUBuffer dst, size_t size) const {
}

// Otherwise, we need to use a staging buffer to upload data.
auto buffer_size = NormalizeBufferSize(size);
auto copy_size = NormalizeCopySize(size);

wgpu::BufferDescriptor desc{};
desc.size = buffer_size;
desc.size = copy_size;
desc.usage = wgpu::BufferUsage::CopySrc | wgpu::BufferUsage::MapWrite;
desc.mappedAtCreation = true;

auto staging_buffer = context_.Device().CreateBuffer(&desc);
mapped_data = staging_buffer.GetMappedRange();
memcpy(mapped_data, src, size);
// Zero padding bytes beyond the actual data to prevent copying garbage
// into the destination buffer when copy_size > size.
if (copy_size > size) {
memset(static_cast<uint8_t*>(mapped_data) + size, 0, copy_size - size);
}
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staging_buffer.Unmap();

auto& command_encoder = context_.GetCommandEncoder();
context_.EndComputePass();
command_encoder.CopyBufferToBuffer(staging_buffer, 0, dst, 0, buffer_size);
command_encoder.CopyBufferToBuffer(staging_buffer, 0, dst, 0, copy_size);
context_.Flush(*this);
}

Expand All @@ -473,16 +483,16 @@ void BufferManager::MemCpy(WGPUBuffer src, WGPUBuffer dst, size_t size) const {
EnforceBufferUnmapped(context_, src);
EnforceBufferUnmapped(context_, dst);

auto buffer_size = NormalizeBufferSize(size);
auto copy_size = NormalizeCopySize(size);
auto src_size = static_cast<size_t>(wgpuBufferGetSize(src));
auto dst_size = static_cast<size_t>(wgpuBufferGetSize(dst));
ORT_ENFORCE(buffer_size <= src_size && buffer_size <= dst_size,
ORT_ENFORCE(copy_size <= src_size && copy_size <= dst_size,
"Source and destination buffers must have enough space for the copy operation. src_size=",
src_size, ", dst_size=", dst_size, ", copy_size=", buffer_size, ".");
src_size, ", dst_size=", dst_size, ", copy_size=", copy_size, ".");

auto& command_encoder = context_.GetCommandEncoder();
context_.EndComputePass();
command_encoder.CopyBufferToBuffer(src, 0, dst, 0, buffer_size);
command_encoder.CopyBufferToBuffer(src, 0, dst, 0, copy_size);
}

WGPUBuffer BufferManager::Create(size_t size, wgpu::BufferUsage usage) const {
Expand Down
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