From 367e7e7b61fdf86ce2cab7122ecc9b3c9642aa9a Mon Sep 17 00:00:00 2001
From: Rowan Hart <rowan.hart@intel.com>
Date: Thu, 28 Sep 2023 09:11:45 -0700
Subject: [PATCH] Fix Box::into_raw and add checks (#27)

---
 simics-api/src/safe/base/attr_value.rs     | 12 +++++++++---
 simics-api/src/safe/base/conf_object.rs    |  6 ++++++
 simics-api/src/safe/simulator/callbacks.rs | 22 +++++++++++++++++-----
 simics-fuzz/src/fuzzer/mod.rs              | 16 +++++++++++++---
 4 files changed, 45 insertions(+), 11 deletions(-)

diff --git a/simics-api/src/safe/base/attr_value.rs b/simics-api/src/safe/base/attr_value.rs
index 513f8893..059bd54a 100644
--- a/simics-api/src/safe/base/attr_value.rs
+++ b/simics-api/src/safe/base/attr_value.rs
@@ -148,11 +148,17 @@ pub fn make_attr_object(obj: *mut ConfObject) -> Result<AttrValue> {
 /// size. The data will be moved into a [`Box`], which will be converted to a raw pointer.
 pub fn make_attr_data_adopt<T>(data: T) -> Result<AttrValue> {
     let data = Box::new(data);
-    let data_ptr = Box::into_raw(data);
+    let data_raw = Box::into_raw(data);
+
+    debug_assert!(
+        std::mem::size_of_val(&data_raw) == std::mem::size_of::<*mut std::ffi::c_void>(),
+        "Pointer is not convertible to *mut c_void"
+    );
+
     let data_size = u32::try_from(size_of::<*mut T>())?;
 
     ensure!(
-        !(data_ptr.is_null() && data_size == 0),
+        !(data_raw.is_null() && data_size == 0),
         "NULL data requires zero size"
     );
 
@@ -160,7 +166,7 @@ pub fn make_attr_data_adopt<T>(data: T) -> Result<AttrValue> {
         private_kind: AttrKind::Data.try_into()?,
         private_size: u32::try_from(data_size)?,
         private_u: attr_value__bindgen_ty_1 {
-            data: data_ptr as *mut u8,
+            data: data_raw as *mut u8,
         },
     })
 }
diff --git a/simics-api/src/safe/base/conf_object.rs b/simics-api/src/safe/base/conf_object.rs
index 2deb1dba..11f32a64 100644
--- a/simics-api/src/safe/base/conf_object.rs
+++ b/simics-api/src/safe/base/conf_object.rs
@@ -68,6 +68,12 @@ where
     // Note: This allocates and never frees. This is *required* by SIMICS and it is an error to
     // free this pointer
     let iface_raw = Box::into_raw(iface_box);
+
+    debug_assert!(
+        std::mem::size_of_val(&iface_raw) == std::mem::size_of::<*mut std::ffi::c_void>(),
+        "Pointer is not convertible to *mut c_void"
+    );
+
     let status = unsafe { SIM_register_interface(cls.into(), name_raw, iface_raw as *mut _) };
 
     if status != 0 {
diff --git a/simics-api/src/safe/simulator/callbacks.rs b/simics-api/src/safe/simulator/callbacks.rs
index d5acb5fd..9a179734 100644
--- a/simics-api/src/safe/simulator/callbacks.rs
+++ b/simics-api/src/safe/simulator/callbacks.rs
@@ -7,17 +7,29 @@ use simics_api_sys::SIM_run_alone;
 
 extern "C" fn run_alone_handler<F>(cb: *mut c_void)
 where
-    F: FnMut(),
+    F: FnOnce() + 'static,
 {
-    let mut closure: Box<F> = unsafe { Box::from_raw(cb as *mut F) };
+    let closure: Box<Box<F>> = unsafe { Box::from_raw(cb as *mut Box<F>) };
     closure()
 }
 
 pub fn run_alone<F>(cb: F)
 where
-    F: FnMut(),
+    F: FnOnce() + 'static,
 {
     let cb = Box::new(cb);
-    let cb = Box::into_raw(cb);
-    unsafe { SIM_run_alone(Some(run_alone_handler::<F>), cb as *mut _ as *mut c_void) }
+    let cb_box = Box::new(cb);
+    let cb_raw = Box::into_raw(cb_box);
+
+    debug_assert!(
+        std::mem::size_of_val(&cb_raw) == std::mem::size_of::<*mut std::ffi::c_void>(),
+        "Pointer is not convertible to *mut c_void"
+    );
+
+    unsafe {
+        SIM_run_alone(
+            Some(run_alone_handler::<F>),
+            cb_raw as *mut _ as *mut c_void,
+        )
+    }
 }
diff --git a/simics-fuzz/src/fuzzer/mod.rs b/simics-fuzz/src/fuzzer/mod.rs
index c7184638..1ff94668 100644
--- a/simics-fuzz/src/fuzzer/mod.rs
+++ b/simics-fuzz/src/fuzzer/mod.rs
@@ -309,12 +309,22 @@ impl SimicsFuzzer {
 
             let tx = Box::new(make_attr_data_adopt(tx)?);
             let rx = Box::new(make_attr_data_adopt(rx)?);
-            let tx = Box::into_raw(tx);
-            let rx = Box::into_raw(rx);
+            let tx_raw = Box::into_raw(tx);
+            let rx_raw = Box::into_raw(rx);
+
+            debug_assert!(
+                std::mem::size_of_val(&tx_raw) == std::mem::size_of::<*mut std::ffi::c_void>(),
+                "Pointer is not convertible to *mut c_void"
+            );
+
+            debug_assert!(
+                std::mem::size_of_val(&rx_raw) == std::mem::size_of::<*mut std::ffi::c_void>(),
+                "Pointer is not convertible to *mut c_void"
+            );
 
             info!("Setting up channels");
 
-            (unsafe { *tsffs_interface }.add_channels)(tsffs, tx, rx);
+            (unsafe { *tsffs_interface }.add_channels)(tsffs, tx_raw, rx_raw);
 
             info!("Set channel for object");