Validate code when scheduling upgrades from registrar

polkadot/runtime/common/src/paras_registrar/mod.rs

@@ -418,6 +418,7 @@ pub mod pallet {
 			new_code: ValidationCode,
 		) -> DispatchResult {
 			Self::ensure_root_para_or_owner(origin, para)?;
+			Self::validate_code(new_code.clone())?;
 			runtime_parachains::schedule_code_upgrade::<T>(para, new_code, SetGoAhead::No)?;
 			Ok(())
 		}
@@ -657,8 +658,7 @@ impl<T: Config> Pallet<T> {
 		para_kind: ParaKind,
 	) -> Result<(ParaGenesisArgs, BalanceOf<T>), sp_runtime::DispatchError> {
 		let config = configuration::Pallet::<T>::config();
-		ensure!(validation_code.0.len() > 0, Error::<T>::EmptyCode);
-		ensure!(validation_code.0.len() <= config.max_code_size as usize, Error::<T>::CodeTooLarge);
+		Self::validate_code(validation_code.clone())?;
 		ensure!(
 			genesis_head.0.len() <= config.max_head_data_size as usize,
 			Error::<T>::HeadDataTooLarge
@@ -681,6 +681,16 @@ impl<T: Config> Pallet<T> {
 		debug_assert!(res2.is_ok());
 		T::OnSwap::on_swap(to_upgrade, to_downgrade);
 	}
+
+	/// Checks whether the provided code is valid.
+	fn validate_code(code: ValidationCode) -> DispatchResult {
+		let config = configuration::Pallet::<T>::config();
+
+		ensure!(code.0.len() > 0, Error::<T>::EmptyCode);
+		ensure!(code.0.len() <= config.max_code_size as usize, Error::<T>::CodeTooLarge);
+
+		Ok(())
+	}
 }
 
 impl<T: Config> OnNewHead for Pallet<T> {
@@ -1032,6 +1042,51 @@ mod tests {
 		});
 	}
 
+	#[test]
+	fn schedule_code_upgrade_validates_code() {
+		new_test_ext().execute_with(|| {
+			const START_SESSION_INDEX: SessionIndex = 1;
+			run_to_session(START_SESSION_INDEX);
+
+			let para_id = LOWEST_PUBLIC_ID;
+			assert!(!Parachains::is_parathread(para_id));
+
+			let validation_code = test_validation_code(32);
+			assert_ok!(Registrar::reserve(RuntimeOrigin::signed(1)));
+			assert_eq!(Balances::reserved_balance(&1), <Test as Config>::ParaDeposit::get());
+			assert_ok!(Registrar::register(
+				RuntimeOrigin::signed(1),
+				para_id,
+				test_genesis_head(32),
+				validation_code.clone(),
+			));
+			conclude_pvf_checking::<Test>(&validation_code, VALIDATORS, START_SESSION_INDEX);
+
+			run_to_session(START_SESSION_INDEX + 2);
+			assert!(Parachains::is_parathread(para_id));
+
+			let new_code = test_validation_code(0);
+			assert_noop!(
+				Registrar::schedule_code_upgrade(
+					RuntimeOrigin::signed(1),
+					para_id,
+					new_code.clone(),
+				),
+				Error::<Test>::EmptyCode
+			);
+
+			let new_code = test_validation_code(max_code_size() as usize + 1);
+			assert_noop!(
+				Registrar::schedule_code_upgrade(
+					RuntimeOrigin::signed(1),
+					para_id,
+					new_code.clone(),
+				),
+				Error::<Test>::CodeTooLarge
+			);
+		});
+	}
+
 	#[test]
 	fn register_handles_basic_errors() {
 		new_test_ext().execute_with(|| {

prdoc/pr_3232.prdoc

@@ -0,0 +1,13 @@
+# Schema: Polkadot SDK PRDoc Schema (prdoc) v1.0.0
+# See doc at https://raw.githubusercontent.com/paritytech/polkadot-sdk/master/prdoc/schema_user.json
+
+title: Validate code when scheduling uprades from registrar
+
+doc:
+  - audience: Runtime User
+    description: |
+      Adds checks to ensure that the validation code is valid before scheduling
+      a code upgrade from the registrar.
+
+crates: 
+  - name: polkadot-runtime-common