fix: bail incomplete bytecode sequence disassemble

crates/cast/src/lib.rs

@@ -2017,7 +2017,7 @@ impl SimpleCast {
     pub fn disassemble(code: &[u8]) -> Result<String> {
         let mut output = String::new();
 
-        for step in decode_instructions(code) {
+        for step in decode_instructions(code)? {
             write!(output, "{:08x}: ", step.pc)?;
 
             if let Some(op) = step.op {
@@ -2290,4 +2290,23 @@ mod tests {
             r#"["0x2b5df5f0757397573e8ff34a8b987b21680357de1f6c8d10273aa528a851eaca","0x","0x","0x2838ac1d2d2721ba883169179b48480b2ba4f43d70fcf806956746bd9e83f903","0x","0xe46fff283b0ab96a32a7cc375cecc3ed7b6303a43d64e0a12eceb0bc6bd87549","0x","0x1d818c1c414c665a9c9a0e0c0ef1ef87cacb380b8c1f6223cb2a68a4b2d023f5","0x","0x","0x","0x236e8f61ecde6abfebc6c529441f782f62469d8a2cc47b7aace2c136bd3b1ff0","0x","0x","0x","0x","0x"]"#
         )
     }
+
+    #[test]
+    fn disassemble_incomplete_sequence() {
+        let incomplete = &hex!("60"); // PUSH1
+        let disassembled = Cast::disassemble(incomplete);
+        assert!(disassembled.is_err());
+
+        let complete = &hex!("6000"); // PUSH1 0x00
+        let disassembled = Cast::disassemble(complete);
+        assert!(disassembled.is_ok());
+
+        let incomplete = &hex!("7fffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffff"); // PUSH32 with 31 bytes
+        let disassembled = Cast::disassemble(incomplete);
+        assert!(disassembled.is_err());
+
+        let complete = &hex!("7fffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffff"); // PUSH32 with 32 bytes
+        let disassembled = Cast::disassemble(complete);
+        assert!(disassembled.is_ok());
+    }
 }

crates/evm/core/src/ic.rs

@@ -1,4 +1,5 @@
 use alloy_primitives::map::HashMap;
+use eyre::Result;
 use revm::interpreter::{
     opcode::{PUSH0, PUSH1, PUSH32},
     OpCode,
@@ -100,18 +101,22 @@ pub struct Instruction<'a> {
 }
 
 /// Decodes raw opcode bytes into [`Instruction`]s.
-pub fn decode_instructions(code: &[u8]) -> Vec<Instruction<'_>> {
+pub fn decode_instructions(code: &[u8]) -> Result<Vec<Instruction<'_>>> {
     let mut pc = 0;
     let mut steps = Vec::new();
 
     while pc < code.len() {
         let op = OpCode::new(code[pc]);
         let immediate_size = op.map(|op| immediate_size(op, &code[pc + 1..])).unwrap_or(0) as usize;
 
+        if pc + 1 + immediate_size > code.len() {
+            eyre::bail!("incomplete sequence of bytecode");
+        }
+
         steps.push(Instruction { op, pc, immediate: &code[pc + 1..pc + 1 + immediate_size] });
 
         pc += 1 + immediate_size;
     }
 
-    steps
+    Ok(steps)
 }