fix(ext/ffi): Check CStr for UTF-8 validity on read (#15318)

Co-authored-by: Phosra <[email protected]>

ext/ffi/lib.rs

@@ -2187,13 +2187,14 @@ where
  permissions.check(None)?;
 
  // SAFETY: Pointer is user provided.
- let cstr = unsafe { CStr::from_ptr(ptr as *const c_char) }.to_bytes();
- let value: v8::Local<v8::Value> =
- v8::String::new_from_utf8(scope, cstr, v8::NewStringType::Normal)
- .ok_or_else(|| {
- type_error("Invalid CString pointer, string exceeds max length")
- })?
- .into();
+ let cstr = unsafe { CStr::from_ptr(ptr as *const c_char) }
+ .to_str()
+ .map_err(|_| type_error("Invalid CString pointer, not valid UTF-8"))?;
+ let value: v8::Local<v8::Value> = v8::String::new(scope, cstr)
+ .ok_or_else(|| {
+ type_error("Invalid CString pointer, string exceeds max length")
+ })?
+ .into();
  Ok(value.into())
 }
 

test_ffi/src/lib.rs

@@ -411,3 +411,10 @@ static STRING: &str = "Hello, world!\0";
 extern "C" fn ffi_string() -> *const u8 {
  STRING.as_ptr()
 }
+
+/// Invalid UTF-8 characters, array of length 14
+#[no_mangle]
+pub static static_char: [u8; 14] = [
+ 0xC0, 0xC1, 0xF5, 0xF6, 0xF7, 0xF8, 0xF9, 0xFA, 0xFB, 0xFC, 0xFD, 0xFE, 0xFF,
+ 0x00,
+];

test_ffi/tests/test.js

@@ -3,6 +3,7 @@
 
 // Run using cargo test or `--v8-options=--allow-natives-syntax`
 
+import { assertEquals } from "https://deno.land/[email protected]/testing/asserts.ts";
 import {
  assertThrows,
 } from "../../test_util/std/testing/asserts.ts";
@@ -186,6 +187,12 @@ const dylib = Deno.dlopen(libPath, {
  "static_ptr": {
  type: "pointer",
  },
+ /**
+ * Invalid UTF-8 characters, buffer of length 14
+ */
+ "static_char": {
+ type: "pointer",
+ },
 });
 const { symbols } = dylib;
 
@@ -478,6 +485,23 @@ uint32Array[0] = 55; // MUTATES!
 console.log("uint32Array[0] after mutation:", uint32Array[0]);
 console.log("Static ptr value after mutation:", view.getUint32());
 
+// Test non-UTF-8 characters
+
+const charView = new Deno.UnsafePointerView(dylib.symbols.static_char);
+
+const charArrayBuffer = charView.getArrayBuffer(14);
+const uint8Array = new Uint8Array(charArrayBuffer);
+assertEquals([...uint8Array], [
+ 0xC0, 0xC1, 0xF5, 0xF6, 0xF7, 0xF8, 0xF9, 0xFA, 0xFB, 0xFC, 0xFD, 0xFE, 0xFF,
+ 0x00
+]);
+
+try {
+ assertThrows(() => charView.getCString(), TypeError, "Invalid CString pointer, not valid UTF-8");
+} catch (_err) {
+ console.log("Invalid UTF-8 characters to `v8::String`:", charView.getCString());
+}
+
 (function cleanup() {
  dylib.close();
  throwCallback.close();