From c46f7689aa937982bfedde693e925898a4dfc819 Mon Sep 17 00:00:00 2001
From: Stanimal <sdbondi@users.noreply.github.com>
Date: Tue, 16 Nov 2021 17:53:04 +0400
Subject: [PATCH] fix: ensure ExecutionStack cannot exceed MAX_STACK_SIZE

---
 src/script/stack.rs       | 10 +++++-----
 src/script/tari_script.rs |  5 +++++
 2 files changed, 10 insertions(+), 5 deletions(-)

diff --git a/src/script/stack.rs b/src/script/stack.rs
index fd23b395..3e2277b1 100644
--- a/src/script/stack.rs
+++ b/src/script/stack.rs
@@ -26,7 +26,7 @@ use tari_utilities::{
     hex::{from_hex, to_hex, Hex, HexError},
     ByteArray,
 };
-pub const MAX_STACK_SIZE: usize = 256;
+pub const MAX_STACK_SIZE: usize = 255;
 
 #[macro_export]
 macro_rules! inputs {
@@ -250,24 +250,24 @@ impl ExecutionStack {
     }
 
     pub fn from_bytes(bytes: &[u8]) -> Result<Self, ScriptError> {
-        let mut items = Vec::new();
+        let mut stack = ExecutionStack { items: Vec::new() };
         let mut byte_str = bytes;
         while !byte_str.is_empty() {
             match StackItem::read_next(byte_str) {
                 Some((item, b)) => {
-                    items.push(item);
+                    stack.push(item)?;
                     byte_str = b;
                 },
                 None => return Err(ScriptError::InvalidInput),
             }
         }
-        Ok(ExecutionStack { items })
+        Ok(stack)
     }
 
     /// Pushes the item onto the top of the stack. This function will only error if the new stack size exceeds the
     /// maximum allowed stack size, given by [MAX_STACK_SIZE]
     pub fn push(&mut self, item: StackItem) -> Result<(), ScriptError> {
-        if self.size() >= MAX_STACK_SIZE {
+        if self.size() > MAX_STACK_SIZE {
             return Err(ScriptError::StackOverflow);
         }
         self.items.push(item);
diff --git a/src/script/tari_script.rs b/src/script/tari_script.rs
index 388576ab..556a9e33 100644
--- a/src/script/tari_script.rs
+++ b/src/script/tari_script.rs
@@ -99,6 +99,11 @@ impl TariScript {
         }
     }
 
+    /// Returns the number of script op codes
+    pub fn size(&self) -> usize {
+        self.script.len()
+    }
+
     fn should_execute(&self, opcode: &Opcode, state: &ExecutionState) -> Result<bool, ScriptError> {
         use Opcode::*;
         match opcode {