Copilot commented on code in PR #582:
URL: https://github.com/apache/avro-rs/pull/582#discussion_r3566842461
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avro/src/codec.rs:
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@@ -167,6 +180,9 @@ impl Codec {
Codec::Snappy => {
let decompressed_size =
snap::raw::decompress_len(&stream[..stream.len() - 4])
.map_err(Details::GetSnappyDecompressLen)?;
+ // The decompressed size is taken from the (untrusted) block
+ // header, so bound it before allocating for it.
+ let decompressed_size =
crate::util::safe_len(decompressed_size)?;
Review Comment:
`Codec::Snappy` slices use `stream.len() - 4`. If the input block is
truncated/corrupt and shorter than 4 bytes (missing the CRC), this will
underflow and the subsequent slice/copy will panic (process abort / DoS). Use a
safe `data_end = stream.len().saturating_sub(4)` (or `checked_sub`) and slice
via `..data_end` / `data_end..` so short inputs return a normal `AvroResult`
error instead of panicking.
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