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Fix use-after-free on Node's cached mutation iterator in write_state #49

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Fix use-after-free on Node's cached mutation iterator in write_state #49

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10 changes: 8 additions & 2 deletions SINGER/SINGER/Node.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -31,9 +31,15 @@ double Node::get_state(double pos) {

void Node::write_state(double pos, double s) {
if (s == 0) {
mutation_sites.erase(pos);
// Erasing the element that the cached iterator `it` points at
// invalidates `it`. Detect that case *before* erasing (while `it` is
// still valid) and let map::erase(it) return the following element, so
// `it` is never left dangling. Reading `it->first` after erase(pos)
// would be a use-after-free.
if (it->first == pos) {
it = mutation_sites.begin();
it = mutation_sites.erase(it);
} else {
mutation_sites.erase(pos);
}
return;
} else if (s == 1) {
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