Fix QEMU userspace crash handler (#1706)

* Fix QEMU userspace crash handler

* no_std

libafl/src/executors/inprocess.rs

@@ -634,6 +634,42 @@ pub fn run_observers_and_save_state<E, EM, OF, Z>(
     log::info!("Bye!");
 }
 
+// TODO remove this after executor refactor and libafl qemu new executor
+/// Expose a version of the crash handler that can be called from e.g. an emulator
+#[cfg(any(unix, feature = "std"))]
+pub fn generic_inproc_crash_handler<E, EM, OF, Z>()
+where
+    E: Executor<EM, Z> + HasObservers,
+    EM: EventFirer<State = E::State> + EventRestarter<State = E::State>,
+    OF: Feedback<E::State>,
+    E::State: HasExecutions + HasSolutions + HasCorpus,
+    Z: HasObjective<Objective = OF, State = E::State>,
+{
+    let data = unsafe { &mut GLOBAL_STATE };
+    let in_handler = data.set_in_handler(true);
+
+    if data.is_valid() {
+        let executor = data.executor_mut::<E>();
+        // disarms timeout in case of TimeoutExecutor
+        executor.post_run_reset();
+        let state = data.state_mut::<E::State>();
+        let event_mgr = data.event_mgr_mut::<EM>();
+        let fuzzer = data.fuzzer_mut::<Z>();
+        let input = data.take_current_input::<<E::State as UsesInput>::Input>();
+
+        run_observers_and_save_state::<E, EM, OF, Z>(
+            executor,
+            state,
+            input,
+            fuzzer,
+            event_mgr,
+            ExitKind::Crash,
+        );
+    }
+
+    data.set_in_handler(in_handler);
+}
+
 /// The inprocess executor singal handling code for unix
 #[cfg(unix)]
 pub mod unix_signal_handler {

libafl_qemu/libafl_qemu_build/src/build.rs

@@ -8,7 +8,7 @@ use which::which;
 
 const QEMU_URL: &str = "https://github.com/AFLplusplus/qemu-libafl-bridge";
 const QEMU_DIRNAME: &str = "qemu-libafl-bridge";
-const QEMU_REVISION: &str = "c105904e6659b3fc90e938438a44254dfe47e1c3";
+const QEMU_REVISION: &str = "32206d23c33a55c9e519e4ae67038ab27d713a24";
 
 fn build_dep_check(tools: &[&str]) {
     for tool in tools {

libafl_qemu/src/executor.rs

@@ -59,16 +59,7 @@ where
 #[cfg(emulation_mode = "usermode")]
 extern "C" {
     // Original QEMU user signal handler
-    fn libafl_qemu_handle_crash(signal: i32, info: *mut siginfo_t, puc: *mut c_void) -> i32;
+    fn libafl_qemu_handle_crash(signal: i32, info: *mut siginfo_t, puc: *mut c_void);
-}
-
-#[cfg(emulation_mode = "usermode")]
-static mut USE_LIBAFL_CRASH_HANDLER: bool = false;
-
-#[cfg(emulation_mode = "usermode")]
-#[no_mangle]
-pub unsafe extern "C" fn libafl_executor_reinstall_handlers() {
-    USE_LIBAFL_CRASH_HANDLER = true;
 }
 
 #[cfg(emulation_mode = "usermode")]
@@ -76,7 +67,7 @@ pub unsafe fn inproc_qemu_crash_handler<E, EM, OF, Z>(
     signal: Signal,
     info: &mut siginfo_t,
     mut context: Option<&mut ucontext_t>,
-    data: &mut InProcessExecutorHandlerData,
+    _data: &mut InProcessExecutorHandlerData,
 ) where
     E: Executor<EM, Z> + HasObservers,
     EM: EventFirer<State = E::State> + EventRestarter<State = E::State>,
@@ -84,20 +75,11 @@ pub unsafe fn inproc_qemu_crash_handler<E, EM, OF, Z>(
     E::State: HasExecutions + HasSolutions + HasCorpus,
     Z: HasObjective<Objective = OF, State = E::State>,
 {
-    let real_crash = if USE_LIBAFL_CRASH_HANDLER {
+    let puc = match &mut context {
-        true
+        Some(v) => (*v) as *mut ucontext_t as *mut c_void,
-    } else {
+        None => core::ptr::null_mut(),
-        let puc = match &mut context {
-            Some(v) => (*v) as *mut ucontext_t as *mut c_void,
-            None => core::ptr::null_mut(),
-        };
-        libafl_qemu_handle_crash(signal as i32, info, puc) != 0
     };
-    if real_crash {
+    libafl_qemu_handle_crash(signal as i32, info, puc);
-        libafl::executors::inprocess::unix_signal_handler::inproc_crash_handler::<E, EM, OF, Z>(
-            signal, info, context, data,
-        );
-    }
 }
 
 #[cfg(emulation_mode = "systemmode")]
@@ -157,6 +139,21 @@ where
             inner.handlers_mut().crash_handler =
                 inproc_qemu_crash_handler::<InProcessExecutor<'a, H, OT, S>, EM, OF, Z>
                     as *const c_void;
+
+            let handler = |hooks: &mut QemuHooks<QT, S>, host_sig| {
+                eprintln!("Crashed with signal {host_sig}");
+                libafl::executors::inprocess::generic_inproc_crash_handler::<
+                    InProcessExecutor<'a, H, OT, S>,
+                    EM,
+                    OF,
+                    Z,
+                >();
+                if let Some(cpu) = hooks.emulator().current_cpu() {
+                    eprint!("Context:\n{}", cpu.display_context());
+                }
+            };
+
+            hooks.crash_closure(Box::new(handler));
         }
         #[cfg(emulation_mode = "systemmode")]
         {