Fix Rust LowLevelILFunction owner function method

LowLevelILFunction objects can be constructed without a owner
function. BNGetLowLevelILOwnerFunction can return NULL and must be
checked before creating a Function object.

Author: zznop

plugins/warp/src/plugin/ffi.rs

@@ -142,7 +142,10 @@ pub unsafe extern "C" fn BNWARPIsLiftedInstructionVariant(
         unsafe { LowLevelILFunction::from_raw(analysis_function) };
     match lifted_il.instruction_from_index(index) {
         Some(instr) => {
-            let relocatable_regions = relocatable_regions(&lifted_il.function().view());
+            let Some(owner_function) = lifted_il.function() else {
+                return false;
+            };
+            let relocatable_regions = relocatable_regions(&owner_function.view());
             is_variant_instruction(&relocatable_regions, &instr)
         }
         None => false,
@@ -158,7 +161,10 @@ pub unsafe extern "C" fn BNWARPIsLowLevelInstructionComputedVariant(
         unsafe { LowLevelILFunction::from_raw(analysis_function) };
     match llil.instruction_from_index(index) {
         Some(instr) => {
-            let relocatable_regions = relocatable_regions(&llil.function().view());
+            let Some(owner_function) = llil.function() else {
+                return false;
+            };
+            let relocatable_regions = relocatable_regions(&owner_function.view());
             is_computed_variant_instruction(&relocatable_regions, &instr)
         }
         None => false,

plugins/warp/src/plugin/render_layer.rs

@@ -48,7 +48,11 @@ impl HighlightRenderLayer {
         llil: &LowLevelILRegularFunction,
         lines: &mut [DisassemblyTextLine],
     ) {
-        let relocatable_regions = relocatable_regions(&lifted_il.function().view());
+        let Some(owner_function) = lifted_il.function() else {
+            return;
+        };
+
+        let relocatable_regions = relocatable_regions(&owner_function.view());
         for line in lines {
             // We use address here instead of index since it's more reliable for other IL's.
             for lifted_il_instr in filtered_instructions_at(lifted_il, line.address) {

rust/src/low_level_il/function.rs

@@ -88,8 +88,9 @@ where
     }
 
     pub(crate) fn arch(&self) -> CoreArchitecture {
+        // TODO: self.function() can return None under rare circumstances
         match self.arch {
-            None => self.function().arch(),
+            None => self.function().unwrap().arch(),
             Some(arch) => arch,
         }
     }
@@ -167,10 +168,13 @@ where
         }
     }
 
-    pub fn function(&self) -> Ref<Function> {
+    pub fn function(&self) -> Option<Ref<Function>> {
         unsafe {
             let func = BNGetLowLevelILOwnerFunction(self.handle);
-            Function::ref_from_raw(func)
+            if func.is_null() {
+                return None;
+            }
+            Some(Function::ref_from_raw(func))
         }
     }