From 5b1b2136916e24aaf9a0ddfe9bd9e58f66357f2f Mon Sep 17 00:00:00 2001
From: Jan-Paul Bultmann
 <74891396+somethingelseentirely@users.noreply.github.com>
Date: Fri, 26 Sep 2025 20:46:55 +0200
Subject: [PATCH] Guard against CompactVector metadata overflow

---
 CHANGELOG.md                      |  1 +
 src/int_vectors/compact_vector.rs | 17 ++++++++++++++++-
 2 files changed, 17 insertions(+), 1 deletion(-)

diff --git a/CHANGELOG.md b/CHANGELOG.md
index 2fc7805..9862d9c 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -1,6 +1,7 @@
 # Changelog
 
 ## Unreleased
+- Guarded `CompactVector::from_bytes` against metadata bit-length overflow.
 - Removed the `anyhow` dependency in favor of crate-defined errors and updated
   `Serializable` to expose an associated error type for reconstruction.
 - Prevent panic in `DacsByte::len` by handling empty level lists gracefully.
diff --git a/src/int_vectors/compact_vector.rs b/src/int_vectors/compact_vector.rs
index 90d6595..76831e6 100644
--- a/src/int_vectors/compact_vector.rs
+++ b/src/int_vectors/compact_vector.rs
@@ -458,7 +458,10 @@ impl Serializable for CompactVector {
     }
 
     fn from_bytes(meta: Self::Meta, bytes: Bytes) -> Result<Self> {
-        let data_len = meta.len * meta.width;
+        let data_len = meta
+            .len
+            .checked_mul(meta.width)
+            .ok_or_else(|| Error::invalid_metadata("len * width overflowed"))?;
         let data = BitVectorData::from_bytes(
             BitVectorDataMeta {
                 len: data_len,
@@ -710,4 +713,16 @@ mod tests {
         let other = CompactVector::from_bytes(meta, bytes).unwrap();
         assert_eq!(cv, other);
     }
+
+    #[test]
+    fn from_bytes_rejects_overflowing_metadata() {
+        let cv = CompactVector::from_slice(&[1]).unwrap();
+        let mut meta = cv.metadata();
+        meta.len = usize::MAX;
+        meta.width = 2;
+        let bytes = cv.chunks.data.words.clone().bytes();
+
+        let err = CompactVector::from_bytes(meta, bytes).unwrap_err();
+        assert!(matches!(err, Error::InvalidMetadata(_)));
+    }
 }