Crash removing a breakpoint via the toolbar (DbgEngAdapter::RemoveBreakpoint) #1175

Sentry: https://vector35.sentry.io/issues/BINARYNINJA-CR

EXCEPTION_ACCESS_VIOLATION_READ / 0x0 when removing a breakpoint from the toolbar.
3 occurrences, first 2026-06-22, last 2026-08-06, all on [email protected] (stable),
Windows 10.0.28120 x86_64.

Reported code location is core/adapters/dbgengadapter.cpp:1276 on stable_5.3.

Stack

QToolButton::mouseReleaseEvent            qtoolbutton.cpp:591
QAbstractButtonPrivate::click             qabstractbutton.cpp:365
QAction::activate / triggered
QtPrivate::QSlotObjectBase::call
  - RtlpLowFragHeapAllocFromContext       <unknown>
DebuggerBreakpoints::ContainsAbsolute     debuggerstate.cpp:713
  - std::vector<T>::_Tidy / allocator::deallocate
DebuggerController::DeleteBreakpoint      debuggercontroller.cpp:83
DebuggerBreakpoints::RemoveAbsolute       debuggerstate.cpp:605
  - std::vector<T>::erase                 vector:1793
DbgEngAdapter::RemoveBreakpoint           dbgengadapter.cpp:1276

The crashed thread reported 0 frames, so Sentry displayed another thread and the unwind is
partly corrupt — a heap allocation frame and vector::_Tidy/deallocate are spliced
between the debugger frames. Treat this as the set of frames involved, not their order.

Hypothesis (unproven)

vector::erase + _Tidy + deallocate appearing next to ContainsAbsolute suggests
container/iterator invalidation: RemoveAbsolute erasing from the breakpoint vector while
something else still holds an iterator or reference into it. This is inferred from a
partly corrupt stack, not established.

Repro angles

Windows + DbgEng. Remove a breakpoint via the toolbar button (the stack is a
QToolButton, not a context menu or the breakpoint pane) at different states:

• while the target is running vs. stopped
• after the target has exited, before teardown
• rapid/double clicks on the remove action
• removing a breakpoint that was never applied, or already removed

Fix status

Not fixed on dev. dbgengadapter.cpp has 5 dev-only commits, none touching breakpoint
lifetime (c8585ad, 1d522b5, a766958, e4b8694, 2ed559b). debuggerstate.cpp got
723b403 (execution/event model refactor), which could perturb this path but does not
target it. Line numbers above are stable_5.3; check dev equivalents before editing.

Not reproduced — investigated from macOS, so this is from the minidump plus reading the
source. DbgEng is Windows-only.