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.