A bug in the SmallVec::insert_many method caused it to allocate a buffer that was smaller than needed. It then wrote past the end of the buffer, causing a buffer overflow and memory corruption on the heap.

This bug was only triggered if the iterator passed to insert_many yielded more items than the lower bound returned from its size_hint method.

The flaw was corrected in smallvec 0.6.14 and 1.6.1, by ensuring that additional space is always reserved for each item inserted. The fix also simplified the implementation of insert_many to use less unsafe code, so it is easier to verify its correctness.

Thank you to Yechan Bae (@Qwaz) and the Rust group at Georgia Tech’s SSLab for finding and reporting this bug.

Shared pointer validation keyed already-validated pointees by their address and type, but did not include pointer metadata. For unsized pointees, an archive could therefore contain multiple Rc, Arc, or weak pointers that shared a data address but used different metadata, such as different slice lengths.

Once the first pointer had been validated, later pointers to the same address skipped pointee validation. The safe checked rkyv::access API could consequently return a slice with a forged length, allowing safe indexing to read out of bounds. The same validation bypass was reachable through checked deserialization with rkyv::from_bytes.

Version 0.8.17 includes pointer metadata in shared pointer validation and rejects conflicting metadata. The 0.7 series is also affected but is no longer supported by upstream. Users who process untrusted archives should upgrade to 0.8.17 or later.