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LibDebug: Make sure current_breakpoint has value before usage

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Previously this caused a crash when no breakpoint was active since we
tried to get value().address before the has_value() check.
This commit is contained in:
Marcus Nilsson 2022-07-02 20:23:19 +02:00 • committed by Brian Gianforcaro
parent 643faa1144
commit da8eea69e4
1 changed files with 23 additions and 21 deletions
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44
Userland/Libraries/LibDebug/DebugSession.h
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@ -278,29 +278,31 @@ void DebugSession::run(DesiredInitialDebugeeState initial_debugee_state, Callbac
bool did_single_step = false;
auto current_breakpoint_address = bit_cast<FlatPtr>(current_breakpoint.value().address);
// Re-enable the breakpoint if it wasn't removed by the user
if (current_breakpoint.has_value() && m_breakpoints.contains(current_breakpoint_address)) {
// The current breakpoint was removed to make it transparent to the user.
// We now want to re-enable it - the code execution flow could hit it again.
// To re-enable the breakpoint, we first perform a single step and execute the
// instruction of the breakpoint, and then redo the INT3 patch in its first byte.
if (current_breakpoint.has_value()) {
auto current_breakpoint_address = bit_cast<FlatPtr>(current_breakpoint.value().address);
if (m_breakpoints.contains(current_breakpoint_address)) {
// The current breakpoint was removed to make it transparent to the user.
// We now want to re-enable it - the code execution flow could hit it again.
// To re-enable the breakpoint, we first perform a single step and execute the
// instruction of the breakpoint, and then redo the INT3 patch in its first byte.
// If the user manually inserted a breakpoint at the current instruction,
// we need to disable that breakpoint because we want to singlestep over that
// instruction (we re-enable it again later anyways).
if (m_breakpoints.contains(current_breakpoint_address) && m_breakpoints.get(current_breakpoint_address).value().state == BreakPointState::Enabled) {
disable_breakpoint(current_breakpoint.value().address);
}
auto stopped_address = single_step();
enable_breakpoint(current_breakpoint.value().address);
did_single_step = true;
// If there is another breakpoint after the current one,
// Then we are already on it (because of single_step)
auto breakpoint_at_next_instruction = m_breakpoints.get(stopped_address);
if (breakpoint_at_next_instruction.has_value()
&& breakpoint_at_next_instruction.value().state == BreakPointState::Enabled) {
state = State::ConsecutiveBreakpoint;
// If the user manually inserted a breakpoint at the current instruction,
// we need to disable that breakpoint because we want to singlestep over that
// instruction (we re-enable it again later anyways).
if (m_breakpoints.contains(current_breakpoint_address) && m_breakpoints.get(current_breakpoint_address).value().state == BreakPointState::Enabled) {
disable_breakpoint(current_breakpoint.value().address);
}
auto stopped_address = single_step();
enable_breakpoint(current_breakpoint.value().address);
did_single_step = true;
// If there is another breakpoint after the current one,
// Then we are already on it (because of single_step)
auto breakpoint_at_next_instruction = m_breakpoints.get(stopped_address);
if (breakpoint_at_next_instruction.has_value()
&& breakpoint_at_next_instruction.value().state == BreakPointState::Enabled) {
state = State::ConsecutiveBreakpoint;
}
}
}