RGBCube/serenity
1
Fork 0
mirror of https://github.com/RGBCube/serenity synced 2025-05-28 16:15:10 +00:00
Code Issues Activity Actions

Kernel: Shrink instead of expand sigaltstack range to page boundaries

Browse source 
Since the POSIX sigaltstack manpage suggests allocating the stack
region using malloc(), and many heap implementations (including ours)
store heap chunk metadata in memory just before the vended pointer,
we would end up zeroing the metadata, leading to various crashes.
This commit is contained in:
Idan Horowitz 2023-12-24 15:53:16 +02:00 • committed by Andreas Kling
parent 4c6fd454d0
commit a49b7e92eb
5 changed files with 29 additions and 34 deletions
Download patch file Download diff file Expand all files Collapse all files

18
Kernel/Tasks/Thread.cpp
View file

@ -752,8 +752,7 @@ void Thread::reset_signals_for_exec()
m_have_any_unmasked_pending_signals.store(false, AK::memory_order_release);
m_signal_action_masks.fill({});
// A successful call to execve(2) removes any existing alternate signal stack
m_alternative_signal_stack = 0;
m_alternative_signal_stack_size = 0;
m_alternative_signal_stack.clear();
}
// Certain exceptions, such as SIGSEGV and SIGILL, put a
@ -881,15 +880,12 @@ bool Thread::is_signal_masked(u8 signal) const
return (1 << (signal - 1)) & m_signal_mask;
}
bool Thread::has_alternative_signal_stack() const
{
return m_alternative_signal_stack_size != 0;
}
bool Thread::is_in_alternative_signal_stack() const
{
auto sp = get_register_dump_from_stack().userspace_sp();
return sp >= m_alternative_signal_stack && sp < m_alternative_signal_stack + m_alternative_signal_stack_size;
if (!m_alternative_signal_stack.has_value())
return false;
return m_alternative_signal_stack->contains(VirtualAddress(sp));
}
static ErrorOr<void> push_value_on_user_stack(FlatPtr& stack, FlatPtr data)
@ -1025,12 +1021,12 @@ DispatchSignalResult Thread::dispatch_signal(u8 signal)
m_signal_mask |= new_signal_mask;
m_have_any_unmasked_pending_signals.store((m_pending_signals & ~m_signal_mask) != 0, AK::memory_order_release);
bool use_alternative_stack = ((action.flags & SA_ONSTACK) != 0) && has_alternative_signal_stack() && !is_in_alternative_signal_stack();
bool use_alternative_stack = ((action.flags & SA_ONSTACK) != 0) && m_alternative_signal_stack.has_value() && !is_in_alternative_signal_stack();
auto setup_stack = [&](RegisterState& state) -> ErrorOr<void> {
FlatPtr stack;
if (use_alternative_stack)
stack = m_alternative_signal_stack + m_alternative_signal_stack_size;
stack = m_alternative_signal_stack->end().get();
else
stack = state.userspace_sp();
@ -1042,7 +1038,7 @@ DispatchSignalResult Thread::dispatch_signal(u8 signal)
.uc_stack = {
.ss_sp = bit_cast<void*>(stack),
.ss_flags = action.flags & SA_ONSTACK,
.ss_size = use_alternative_stack ? m_alternative_signal_stack_size : 0,
.ss_size = use_alternative_stack ? m_alternative_signal_stack->size() : 0,
},
.uc_mcontext = {},
};