ffi: validate 'void' as parameter type in getFunction and getFunctions

src/ffi/types.cc

@@ -202,6 +202,15 @@ Maybe<FunctionSignature> ParseFunctionSignature(Environment* env,
       if (!ToFFIType(env, arg_str.ToStringView()).To(&arg_type)) {
         return {};
       }
+      if (arg_type == &ffi_type_void) {
+        THROW_ERR_INVALID_ARG_VALUE(
+            env,
+            "Argument %u of function %s must not be 'void'; "
+            "use an empty array for no-argument functions",
+            i,
+            name);
+        return {};
+      }
 
       args.push_back(arg_type);
       arg_type_names.emplace_back(arg_str.ToString());

test/parallel/test-ffi-void-parameter.js

@@ -0,0 +1,33 @@
+'use strict';
+
+const common = require('../common');
+
+if (!process.config.variables.node_use_ffi) {
+  common.skip('requires FFI support');
+}
+
+const assert = require('node:assert');
+const { spawnSync } = require('node:child_process');
+
+// Regression test for https://github.com/nodejs/node/issues/63461
+// 'void' as a parameter type should throw ERR_INVALID_ARG_VALUE
+// instead of triggering ERR_INTERNAL_ASSERTION.
+
+{
+  const { stderr, status } = spawnSync(process.execPath, [
+    '--expose-internals',
+    '-e',
+    `
+      const { internalBinding } = require('internal/test/binding');
+      const { DynamicLibrary } = internalBinding('ffi');
+      const lib = new DynamicLibrary(null);
+      lib.getFunction('f', { parameters: ['void'] });
+    `,
+  ], {
+    encoding: 'utf8',
+  });
+
+  assert.strictEqual(status, 1);
+  assert.match(stderr, /ERR_INVALID_ARG_VALUE/);
+  assert.doesNotMatch(stderr, /ERR_INTERNAL_ASSERTION/);
+}