add decode with depth limit to opaque types (#11947)

Co-authored-by: parity-processbot <>

substrate/frame/support/src/traits/misc.rs

@@ -18,7 +18,7 @@
 //! Smaller traits used in FRAME which don't need their own file.
 
 use crate::dispatch::Parameter;
-use codec::{CompactLen, Decode, DecodeAll, Encode, EncodeLike, Input, MaxEncodedLen};
+use codec::{CompactLen, Decode, DecodeLimit, Encode, EncodeLike, Input, MaxEncodedLen};
 use scale_info::{build::Fields, meta_type, Path, Type, TypeInfo, TypeParameter};
 use sp_arithmetic::traits::{CheckedAdd, CheckedMul, CheckedSub, Saturating};
 #[doc(hidden)]
@@ -745,7 +745,10 @@ impl<T: Encode> Encode for WrapperOpaque<T> {
 
 impl<T: Decode> Decode for WrapperOpaque<T> {
 	fn decode<I: Input>(input: &mut I) -> Result<Self, codec::Error> {
-		Ok(Self(T::decode_all(&mut &<Vec<u8>>::decode(input)?[..])?))
+		Ok(Self(T::decode_all_with_depth_limit(
+			sp_api::MAX_EXTRINSIC_DEPTH,
+			&mut &<Vec<u8>>::decode(input)?[..],
+		)?))
 	}
 
 	fn skip<I: Input>(input: &mut I) -> Result<(), codec::Error> {
@@ -807,7 +810,7 @@ impl<T: Decode> WrapperKeepOpaque<T> {
 	///
 	/// Returns `None` if the decoding failed.
 	pub fn try_decode(&self) -> Option<T> {
-		T::decode_all(&mut &self.data[..]).ok()
+		T::decode_all_with_depth_limit(sp_api::MAX_EXTRINSIC_DEPTH, &mut &self.data[..]).ok()
 	}
 
 	/// Returns the length of the encoded `T`.
@@ -939,6 +942,30 @@ impl<Hash> PreimageRecipient<Hash> for () {
 #[cfg(test)]
 mod test {
 	use super::*;
+	use sp_std::marker::PhantomData;
+
+	#[derive(Encode, Decode)]
+	enum NestedType {
+		Nested(Box<Self>),
+		Done,
+	}
+
+	#[test]
+	fn test_opaque_wrapper_decode_limit() {
+		let limit = sp_api::MAX_EXTRINSIC_DEPTH as usize;
+		let mut ok_bytes = vec![0u8; limit];
+		ok_bytes.push(1u8);
+		let mut err_bytes = vec![0u8; limit + 1];
+		err_bytes.push(1u8);
+		assert!(<WrapperOpaque<NestedType>>::decode(&mut &ok_bytes.encode()[..]).is_ok());
+		assert!(<WrapperOpaque<NestedType>>::decode(&mut &err_bytes.encode()[..]).is_err());
+
+		let ok_keep_opaque = WrapperKeepOpaque { data: ok_bytes, _phantom: PhantomData };
+		let err_keep_opaque = WrapperKeepOpaque { data: err_bytes, _phantom: PhantomData };
+
+		assert!(<WrapperKeepOpaque<NestedType>>::try_decode(&ok_keep_opaque).is_some());
+		assert!(<WrapperKeepOpaque<NestedType>>::try_decode(&err_keep_opaque).is_none());
+	}
 
 	#[test]
 	fn test_opaque_wrapper() {