From 253830d235ffc961425dcdc0176deb28a1675ade Mon Sep 17 00:00:00 2001
From: Herr Seppia <seppia@dusk.network>
Date: Mon, 16 Dec 2024 10:33:53 +0100
Subject: [PATCH] consensus: use prev_state_root for verification

---
 consensus/src/commons.rs                  |  6 ++++++
 consensus/src/operations.rs               |  2 ++
 consensus/src/proposal/block_generator.rs |  1 +
 consensus/src/validation/step.rs          | 15 +++++++++++++--
 4 files changed, 22 insertions(+), 2 deletions(-)

diff --git a/consensus/src/commons.rs b/consensus/src/commons.rs
index 674f66eeb..5dc108b81 100644
--- a/consensus/src/commons.rs
+++ b/consensus/src/commons.rs
@@ -33,6 +33,7 @@ pub struct RoundUpdate {
 
     seed: Seed,
     hash: [u8; 32],
+    state_root: [u8; 32],
     att: Attestation,
     att_voters: Vec<Voter>,
     timestamp: u64,
@@ -59,6 +60,7 @@ impl RoundUpdate {
             timestamp: tip_header.timestamp,
             base_timeouts,
             att_voters,
+            state_root: tip_header.state_hash,
         }
     }
 
@@ -81,6 +83,10 @@ impl RoundUpdate {
     pub fn att_voters(&self) -> &Vec<Voter> {
         &self.att_voters
     }
+
+    pub fn state_root(&self) -> [u8; 32] {
+        self.state_root
+    }
 }
 
 #[async_trait::async_trait]
diff --git a/consensus/src/operations.rs b/consensus/src/operations.rs
index 4b776aec9..99246a082 100644
--- a/consensus/src/operations.rs
+++ b/consensus/src/operations.rs
@@ -26,6 +26,7 @@ pub struct CallParams {
     pub to_slash: Vec<Slash>,
     pub voters_pubkey: Vec<Voter>,
     pub max_txs_bytes: usize,
+    pub prev_state_root: StateRoot,
 }
 
 #[derive(Default)]
@@ -77,6 +78,7 @@ pub trait Operations: Send + Sync {
 
     async fn verify_state_transition(
         &self,
+        prev_commit: StateRoot,
         blk: &Block,
         voters: &[Voter],
     ) -> Result<VerificationOutput, OperationError>;
diff --git a/consensus/src/proposal/block_generator.rs b/consensus/src/proposal/block_generator.rs
index 5ee57eddc..fe56b2103 100644
--- a/consensus/src/proposal/block_generator.rs
+++ b/consensus/src/proposal/block_generator.rs
@@ -132,6 +132,7 @@ impl<T: Operations> Generator<T> {
             to_slash,
             voters_pubkey: voters.to_owned(),
             max_txs_bytes,
+            prev_state_root: ru.state_root(),
         };
 
         let result =
diff --git a/consensus/src/validation/step.rs b/consensus/src/validation/step.rs
index 01dc02418..ae3b38882 100644
--- a/consensus/src/validation/step.rs
+++ b/consensus/src/validation/step.rs
@@ -103,7 +103,14 @@ impl<T: Operations + 'static, D: Database> ValidationStep<T, D> {
                     error!(event = "invalid faults", ?err);
                     Vote::Invalid(header.hash)
                 } else {
-                    match Self::call_vst(candidate, &voters, &executor).await {
+                    match Self::call_vst(
+                        ru.state_root(),
+                        candidate,
+                        &voters,
+                        &executor,
+                    )
+                    .await
+                    {
                         Ok(_) => Vote::Valid(header.hash),
                         Err(err) => {
                             error!(event = "failed_vst_call", ?err);
@@ -154,11 +161,15 @@ impl<T: Operations + 'static, D: Database> ValidationStep<T, D> {
     }
 
     async fn call_vst(
+        prev_commit: [u8; 32],
         candidate: &Block,
         voters: &[Voter],
         executor: &Arc<T>,
     ) -> anyhow::Result<()> {
-        match executor.verify_state_transition(candidate, voters).await {
+        match executor
+            .verify_state_transition(prev_commit, candidate, voters)
+            .await
+        {
             Ok(output) => {
                 // Ensure the `event_bloom` and `state_root` returned
                 // from the VST call are the