filter invalidly signed commitments at call site

only correctly signed commitments that equivocate should be reported. If
the signature is invalid, we should skip the validator from the
equivocation report and only report those who have validly signed the
equivocation (i.e. if signature on vote is invalid not report it at all).

Author: Lederstrumpf

substrate/client/consensus/beefy/src/communication/fisherman.rs

@@ -47,8 +47,8 @@ pub(crate) trait BeefyFisherman<B: Block>: Send + Sync {
 		vote: VoteMessage<NumberFor<B>, AuthorityId, Signature>,
 	) -> Result<(), Error>;
 
-	/// Check `signed_commitment` for contained block against canonical payload. If an equivocation is detected,
-	/// this should also report it.
+	/// Check `signed_commitment` for contained block against canonical payload. If an equivocation
+	/// is detected, this should also report it.
 	fn check_signed_commitment(
 		&self,
 		signed_commitment: SignedCommitment<NumberFor<B>, Signature>,
@@ -240,6 +240,14 @@ where
 		vote: VoteMessage<NumberFor<B>, AuthorityId, Signature>,
 	) -> Result<(), Error> {
 		let number = vote.commitment.block_number;
+		// if the vote's commitment has not been signed by the purported signer, we ignore it
+		if !sp_consensus_beefy::check_commitment_signature(
+			&vote.commitment,
+			&vote.id,
+			&vote.signature,
+		) {
+			return Ok(())
+		};
 		// if the vote is for a block number exceeding our best block number, there shouldn't even
 		// be a payload to sign yet, hence we assume it is an equivocation and report it
 		if number > self.backend.blockchain().info().best_number {
@@ -302,7 +310,20 @@ where
 				.iter()
 				.cloned()
 				.zip(signatures.into_iter())
-				.filter_map(|(id, signature)| signature.map(|sig| (id, sig)))
+				.filter_map(|(id, signature)| match signature {
+					Some(sig) =>
+						if sp_consensus_beefy::check_commitment_signature::<
+							_,
+							_,
+							BeefySignatureHasher,
+						>(&commitment, &id, &sig)
+						{
+							Some((id, sig))
+						} else {
+							None
+						},
+					None => None,
+				})
 				.collect();
 			if signatories.len() > 0 {
 				let proof = ForkEquivocationProof {