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GH-46704: [C++] Fix OSS-Fuzz build failure #46706

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Merged
pitrou merged 1 commit into from
Jun 9, 2025
Merged

GH-46704: [C++] Fix OSS-Fuzz build failure #46706

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10 changes: 6 additions & 4 deletions cpp/build-support/fuzzing/pack_corpus.py
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Original file line number Diff line number Diff line change
Expand Up @@ -27,18 +27,20 @@


def process_dir(corpus_dir, zip_output):
seen = set()
seen_hashes = {}

for child in corpus_dir.iterdir():
if not child.is_file():
raise IOError(f"Not a file: {child}")
with child.open('rb') as f:
data = f.read()
arcname = hashlib.sha1(data).hexdigest()
if arcname in seen:
raise ValueError(f"Duplicate hash: {arcname} (in file {child})")
if arcname in seen_hashes:
raise ValueError(
f"Duplicate hash: {arcname} (in file {child}), "
f"already seen in file {seen_hashes[arcname]}")
zip_output.writestr(str(arcname), data)
seen.add(arcname)
seen_hashes[arcname] = child


def main(corpus_dir, zip_output_name):
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2 changes: 1 addition & 1 deletion cpp/src/arrow/ipc/test_common.cc
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Expand Up @@ -474,7 +474,7 @@ Status MakeListViewRecordBatchSized(const int length, std::shared_ptr<RecordBatc
}

Status MakeListViewRecordBatch(std::shared_ptr<RecordBatch>* out) {
return MakeListRecordBatchSized(200, out);
return MakeListViewRecordBatchSized(200, out);
}

Status MakeFixedSizeListRecordBatch(std::shared_ptr<RecordBatch>* out) {
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18 changes: 15 additions & 3 deletions cpp/src/arrow/ipc/writer.cc
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Expand Up @@ -329,15 +329,24 @@ class RecordBatchSerializer {
return Status::OK();
}

int64_t required_bytes = sizeof(offset_type) * (array.length() + 1);
if (array.value_offset(0) > 0) {
const int64_t required_bytes = sizeof(offset_type) * (array.length() + 1);

offset_type first_offset = 0;
RETURN_NOT_OK(MemoryManager::CopyBufferSliceToCPU(
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@zanmato1984 zanmato1984 Jun 6, 2025

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I think I'll need some context here. Is this function supposed to be able to deal with non-CPU arrays? Does this rule apply to other functions in this source file too?

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@pitrou pitrou Jun 9, 2025

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Yes, it's supposed to.

array.data()->buffers[1], array.offset() * sizeof(offset_type),
sizeof(offset_type), reinterpret_cast<uint8_t*>(&first_offset)));

if (first_offset > 0) {
// If the offset of the first value is non-zero, then we must create a new
// offsets buffer with shifted offsets.
if (!array.data()->buffers[1]->is_cpu()) {
return Status::NotImplemented("Rebasing non-CPU offsets");
}
Comment on lines +342 to +344
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@zanmato1984 zanmato1984 Jun 6, 2025 •
edited
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Two questions:

  1. Is this error handling necessary to fix the "CUDA tests" mentioned in the PR description?
  2. It appears that if the CUDA tests were failing with accessing the non-CPU first_offset, and the above MemoryManager::CopyBufferSliceToCPU is supposed to fix it, wouldn't this check fail the tests again with Unimplemented? (I assume the said tests are exercising non-CPU buffers with first_offset > 0.)

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@pitrou pitrou Jun 9, 2025

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  1. Yes
  2. This codepath is only taken with a non-zero first offset, but the CUDA tests don't exercise that (otherwise they would have been crashing on git main too)

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@pitrou pitrou Jun 9, 2025

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I've opened #46747 for this.

ARROW_ASSIGN_OR_RAISE(auto shifted_offsets,
AllocateBuffer(required_bytes, options_.memory_pool));

auto dest_offsets = shifted_offsets->mutable_span_as<offset_type>();
const offset_type* source_offsets = array.raw_value_offsets();
auto dest_offsets = shifted_offsets->mutable_span_as<offset_type>();
const offset_type start_offset = source_offsets[0];

for (int i = 0; i <= array.length(); ++i) {
Expand Down Expand Up @@ -369,6 +378,9 @@ class RecordBatchSerializer {
// If we have a non-zero offset, it's likely that the smallest offset is
// not zero. We must a) create a new offsets array with shifted offsets and
// b) slice the values array accordingly.
if (!array.data()->buffers[1]->is_cpu()) {
return Status::NotImplemented("Rebasing non-CPU list view offsets");
}

ARROW_ASSIGN_OR_RAISE(auto shifted_offsets,
AllocateBuffer(required_bytes, options_.memory_pool));
Expand Down
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