feat(example): add overflow stack example

Cargo.toml

@@ -2,7 +2,7 @@
 name = "jolt"
 version = "0.1.0"
 authors = [
-    # author of original Spartan paper and code base 
+    # author of original Spartan paper and code base
     "Srinath Setty <srinath@microsoft.com>",
     # authors who contributed to the Arkworks Spartan fork
     "Zhenfei Zhang <zhenfei.zhang@hotmail.com>",
@@ -46,6 +46,10 @@ members = [
     "examples/stdlib/guest",
     "examples/muldiv",
     "examples/muldiv/guest",
+    "examples/overflow",
+    "examples/overflow/guest",
+
+
 ]
 
 [features]

examples/overflow/Cargo.toml

@@ -0,0 +1,8 @@
+[package]
+name = "overflow"
+version = "0.1.0"
+edition = "2021"
+
+[dependencies]
+jolt-sdk = { path = "../../jolt-sdk", features = ["host"] }
+guest = { package = "overflow-guest", path = "./guest" }

examples/overflow/guest/Cargo.toml

@@ -0,0 +1,14 @@
+[package]
+name = "overflow-guest"
+version = "0.1.0"
+edition = "2021"
+
+[[bin]]
+name = "guest"
+path = "./src/lib.rs"
+
+[features]
+guest = []
+
+[dependencies]
+jolt = { package = "jolt-sdk", path = "../../../jolt-sdk" }

examples/overflow/guest/src/lib.rs

@@ -0,0 +1,12 @@
+#![cfg_attr(feature = "guest", no_std)]
+#![no_main]
+
+const ARRAY_SIZE: usize = 2048;
+
+#[jolt::provable(stack_size = 1024)]
+fn overflow_stack() -> u32 {
+    let arr = [1; ARRAY_SIZE];
+
+    let sum = arr.iter().fold(0u32, |acc, &x| acc.wrapping_add(x));
+    sum
+}

examples/overflow/src/main.rs

@@ -0,0 +1,21 @@
+use std::panic;
+
+pub fn main() {
+    let (prove_overflow_atack, verify_overflow_stack) = guest::build_overflow_stack();
+
+    let result = panic::catch_unwind(|| {
+        let (_, proof) = prove_overflow_atack();
+        verify_overflow_stack(proof);
+    });
+
+    match &result {
+        Err(e) => match e.downcast_ref::<String>() {
+            Some(msg) => println!("Panic occurred with message: {}", msg),
+            None => println!("Panic occurred with unknown message type"),
+        },
+        Ok(_) => println!("No panic occurred"),
+    }
+
+    // println!("output: {}", output);
+    // println!("valid: {}", is_valid);
+}

tracer/src/emulator/mmu.rs

@@ -252,7 +252,7 @@ impl Mmu {
             // less then DRAM_BASE and greater then panic => zero_padding region
             assert!(
                 effective_address <= self.jolt_device.memory_layout.termination,
-                "Stack overflow: Attempted to write to 0x{:X}, which is in the area or zero padding region.",
+                "Stack overflow: Attempted to write to 0x{:X}, which is in the area of zero padding region.",
                 effective_address
             );
             // less then panic => jolt_device region (i.e. input/output)
@@ -673,7 +673,10 @@ impl Mmu {
                 0x0c000000..=0x0fffffff => self.plic.store(effective_address, value),
                 0x10000000..=0x100000ff => self.uart.store(effective_address, value),
                 0x10001000..=0x10001FFF => self.disk.store(effective_address, value),
-                _ => self.assert_effective_address(effective_address),
+                _ => {
+                    self.assert_effective_address(effective_address);
+                    self.jolt_device.store(effective_address, value);
+                }
             },
         };
     }