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fix(zstd): return decode error instead of panicking on corrupt view lengths #8843

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fix(zstd): return decode error instead of panicking on corrupt view lengths #8843

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45 changes: 36 additions & 9 deletions encodings/zstd/src/array.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -475,7 +475,7 @@ fn collect_valid_vbv(
pub fn reconstruct_views(
buffer: &ByteBuffer,
max_buffer_len: usize,
) -> (Vec<ByteBuffer>, Buffer<BinaryView>) {
) -> VortexResult<(Vec<ByteBuffer>, Buffer<BinaryView>)> {
let mut views = BufferMut::<BinaryView>::empty();
let mut buffers = Vec::new();
let mut segment_start: usize = 0;
Expand All @@ -485,7 +485,12 @@ pub fn reconstruct_views(
let str_len = ViewLen::from_le_bytes(
buffer
.get(offset..offset + size_of::<ViewLen>())
.vortex_expect("corrupted zstd length")
.ok_or_else(|| {
vortex_err!(
"corrupted zstd data: truncated view length prefix at offset {offset} (buffer length {})",
buffer.len()
)
})?
.try_into()
.ok()
.vortex_expect("must fit ViewLen size"),
Expand All @@ -502,16 +507,27 @@ pub fn reconstruct_views(
let local_offset = u32::try_from(value_data_offset - segment_start)
.vortex_expect("local offset within segment must fit in u32");
let buf_index = u32::try_from(buffers.len()).vortex_expect("buffer index must fit in u32");
let value = &buffer[value_data_offset..value_data_offset + str_len];
let value_end = value_data_offset.checked_add(str_len).ok_or_else(|| {
vortex_err!(
"corrupted zstd data: view of length {str_len} at offset {value_data_offset} exceeds buffer length {}",
buffer.len()
)
})?;
let value = buffer.get(value_data_offset..value_end).ok_or_else(|| {
vortex_err!(
"corrupted zstd data: view of length {str_len} at offset {value_data_offset} exceeds buffer length {}",
buffer.len()
)
})?;
views.push(BinaryView::make_view(value, buf_index, local_offset));
offset = value_data_offset + str_len;
offset = value_end;
}

if segment_start < buffer.len() {
buffers.push(buffer.slice(segment_start..buffer.len()));
}

(buffers, views.freeze())
Ok((buffers, views.freeze()))
}

impl ZstdData {
Expand Down Expand Up @@ -1016,7 +1032,8 @@ impl ZstdData {
DType::Binary(_) | DType::Utf8(_) => {
match slice_validity.execute_mask(slice_n_rows, ctx)?.indices() {
AllOr::All => {
let (buffers, all_views) = reconstruct_views(&decompressed, MAX_BUFFER_LEN);
let (buffers, all_views) =
reconstruct_views(&decompressed, MAX_BUFFER_LEN)?;
let valid_views = all_views.slice(
slice_value_idx_start - n_skipped_values
..slice_value_idx_stop - n_skipped_values,
Expand All @@ -1039,7 +1056,8 @@ impl ZstdData {
)
.into_array()),
AllOr::Some(valid_indices) => {
let (buffers, all_views) = reconstruct_views(&decompressed, MAX_BUFFER_LEN);
let (buffers, all_views) =
reconstruct_views(&decompressed, MAX_BUFFER_LEN)?;
let valid_views = all_views.slice(
slice_value_idx_start - n_skipped_values
..slice_value_idx_stop - n_skipped_values,
Expand Down Expand Up @@ -1151,7 +1169,7 @@ mod tests {
fn test_reconstruct_views_no_split() {
let strings: &[&[u8]] = &[b"hello", b"world"];
let buf = make_interleaved(strings);
let (buffers, views) = reconstruct_views(&buf, 1024);
let (buffers, views) = reconstruct_views(&buf, 1024).unwrap();

assert_eq!(buffers.len(), 1);
assert_eq!(views.len(), 2);
Expand All @@ -1168,12 +1186,21 @@ mod tests {
// so it rolls into a second segment.
let strings: &[&[u8]] = &[b"aaaaaaaaaaaaa", b"bbbbbbbbbbbbb"];
let buf = make_interleaved(strings);
let (buffers, views) = reconstruct_views(&buf, 20);
let (buffers, views) = reconstruct_views(&buf, 20).unwrap();

assert_eq!(buffers.len(), 2);
assert_eq!(views.len(), 2);
assert_eq!(views[0], BinaryView::make_view(b"aaaaaaaaaaaaa", 0, 4));
// Second entry starts a new segment at byte 17 (the length prefix), so local offset = 4.
assert_eq!(views[1], BinaryView::make_view(b"bbbbbbbbbbbbb", 1, 4));
}

#[test]
fn test_reconstruct_views_corrupt_length_returns_error() {
let buf = ByteBuffer::copy_from([0xff_u8, 0xff, 0xff, 0x7f, 0x01, 0x02].as_slice());
assert!(reconstruct_views(&buf, 1024).is_err());

let truncated_prefix = ByteBuffer::copy_from([0x01_u8, 0x02].as_slice());
assert!(reconstruct_views(&truncated_prefix, 1024).is_err());
}
}
2 changes: 1 addition & 1 deletion vortex-cuda/src/kernel/encodings/zstd.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -331,7 +331,7 @@ async fn decode_zstd(array: ZstdArray, ctx: &mut CudaExecutionCtx) -> VortexResu
.indices()
{
AllOr::All => {
let (buffers, all_views) = reconstruct_views(&host_buffer, MAX_BUFFER_LEN);
let (buffers, all_views) = reconstruct_views(&host_buffer, MAX_BUFFER_LEN)?;
let sliced_views = all_views.slice(slice_value_idx_start..slice_value_idx_stop);

Ok(Canonical::VarBinView(unsafe {
Expand Down
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