Kernel: Wrap process address spaces in SpinlockProtected

This forces anyone who wants to look into and/or manipulate an address
space to lock it. And this replaces the previous, more flimsy, manual
spinlock use.

Note that pointers *into* the address space are not safe to use after
you unlock the space. We've got many issues like this, and we'll have
to track those down as wlel.

3 files changed, 11 insertions, 4 deletions

diff --git a/Kernel/Arch/x86/common/CrashHandler.cpp b/Kernel/Arch/x86/common/CrashHandler.cpp
index df0ba7c214..c33276717a 100644
--- a/Kernel/Arch/x86/common/CrashHandler.cpp
+++ b/Kernel/Arch/x86/common/CrashHandler.cpp
@@ -35,7 +35,7 @@ void handle_crash(Kernel::RegisterState const& regs, char const* description, in
     dump_registers(regs);
 
     if (crashed_in_kernel) {
-        process.address_space().dump_regions();
+        process.address_space().with([&](auto& space) { space->dump_regions(); });
         PANIC("Crash in ring 0");
     }
 
diff --git a/Kernel/Arch/x86/common/Interrupts.cpp b/Kernel/Arch/x86/common/Interrupts.cpp
index e91de65693..604a74da33 100644
--- a/Kernel/Arch/x86/common/Interrupts.cpp
+++ b/Kernel/Arch/x86/common/Interrupts.cpp
@@ -303,9 +303,15 @@ void page_fault_handler(TrapFrame* trap)
     };
 
     VirtualAddress userspace_sp = VirtualAddress { regs.userspace_sp() };
-    if (!faulted_in_kernel && !MM.validate_user_stack(current_thread->process().address_space(), userspace_sp)) {
-        dbgln("Invalid stack pointer: {}", userspace_sp);
-        return handle_crash(regs, "Bad stack on page fault", SIGSEGV);
+
+    if (!faulted_in_kernel) {
+        bool has_valid_stack_pointer = current_thread->process().address_space().with([&](auto& space) {
+            return MM.validate_user_stack(*space, userspace_sp);
+        });
+        if (!has_valid_stack_pointer) {
+            dbgln("Invalid stack pointer: {}", userspace_sp);
+            return handle_crash(regs, "Bad stack on page fault", SIGSEGV);
+        }
     }
 
     PageFault fault { regs.exception_code, VirtualAddress { fault_address } };
diff --git a/Kernel/Arch/x86/common/Spinlock.cpp b/Kernel/Arch/x86/common/Spinlock.cpp
index 4de2eecfc0..5af0b61495 100644
--- a/Kernel/Arch/x86/common/Spinlock.cpp
+++ b/Kernel/Arch/x86/common/Spinlock.cpp
@@ -55,6 +55,7 @@ u32 RecursiveSpinlock::lock()
 
 void RecursiveSpinlock::unlock(u32 prev_flags)
 {
+    VERIFY_INTERRUPTS_DISABLED();
     VERIFY(m_recursions > 0);
     VERIFY(m_lock.load(AK::memory_order_relaxed) == FlatPtr(&Processor::current()));
     if (--m_recursions == 0) {