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Bound file-controlled node index against _n_nodes in the query tree walk (OOB read on crafted .ann) #697

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Bound file-controlled node index against _n_nodes in the query tree walk (OOB read on crafted .ann) #697

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Bound file-controlled node index against _n_nodes in the query tree walk
professor-moody Jul 17, 2026
35b161f
Bound the leaf children copied into nns, and guard before forming the…
professor-moody Jul 31, 2026
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17 changes: 15 additions & 2 deletions src/annoylib.h
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Original file line number Diff line number Diff line change
Expand Up @@ -1226,7 +1226,8 @@ template<typename S, typename T, typename Distance, typename Random, class Threa
}

void get_nns_by_item(S item, size_t n, int search_k, vector<S>* result, vector<T>* distances) const {
// TODO: handle OOB
if (item < 0 || item >= _n_nodes)
return;
const Node* m = _get(item);
_get_all_nns(m->v, n, search_k, result, distances);
}
Expand Down Expand Up @@ -1465,11 +1466,19 @@ template<typename S, typename T, typename Distance, typename Random, class Threa
const pair<T, S>& top = q.top();
T d = top.first;
S i = top.second;
Node* nd = _get(i);
q.pop();
// i comes from the file (a child index), so it must be bounded before it
// is turned into a pointer, not merely before that pointer is read.
if (i < 0 || i >= _n_nodes)
continue;
Node* nd = _get(i);
if (nd->n_descendants == 1 && i < _n_items) {
nns.push_back(i);
} else if (nd->n_descendants <= _K) {
// n_descendants is file controlled here too; zero is legitimate (an
// empty leaf), negative is not, and would run the copy backwards.
if (nd->n_descendants < 0)
continue;
const S* dst = nd->children;
nns.insert(nns.end(), dst, &dst[nd->n_descendants]);
} else {
Expand All @@ -1489,6 +1498,10 @@ template<typename S, typename T, typename Distance, typename Random, class Threa
if (j == last)
continue;
last = j;
// the entries copied out of a leaf's children[] above are file controlled
// and reach _get() here without ever passing through the loop guard.
if (j < 0 || j >= _n_nodes)
continue;
if (_get(j)->n_descendants == 1) // This is only to guard a really obscure case, #284
nns_dist.push_back(make_pair(D::distance(v_node, _get(j), _f), j));
}
Expand Down