fix: Avoid arithmetic overflow and panics

src/mach/exports.rs

@@ -274,10 +274,16 @@ impl<'a> ExportTrie<'a> {
     /// Create a new, lazy, zero-copy export trie from the `DyldInfo` `command`
     pub fn new(bytes: &'a [u8], command: &load_command::DyldInfoCommand) -> Self {
         let start = command.export_off as usize;
-        let end = (command.export_size + command.export_off) as usize;
+        let end = start.saturating_add(command.export_size as usize);
+        // FIXME: Ideally, this should validate `command`, but the best we can
+        // do for now is return an empty `Range`.
+        let mut location = start..end;
+        if bytes.get(location.clone()).is_none() {
+            location = 0..0;
+        }
         ExportTrie {
             data: bytes,
-            location: start..end,
+            location,
         }
     }
 }
@@ -316,4 +322,15 @@ mod tests {
         println!("len: {} exports: {:#?}", exports.len(), &exports);
         assert_eq!(exports.len() as usize, 3usize)
     }
+
+    #[test]
+    fn invalid_range() {
+        let mut command = load_command::DyldInfoCommand::default();
+        command.export_off = 0xffff_ff00;
+        command.export_size = 0x00ff_ff00;
+        let trie = ExportTrie::new(&[], &command);
+        // FIXME: it would have been nice if this were an `Err`.
+        let exports = trie.exports(&[]).unwrap();
+        assert_eq!(exports.len(), 0);
+    }
 }