create vm diff fuzzer

Makefile

@@ -304,9 +304,15 @@ clean:
 	rm -rf cairo-vm-pypy-env
 	rm -rf cairo
 
-fuzzer-deps: 
+fuzzer-deps: build
 	cargo +nightly install cargo-fuzz
+	. cairo-vm-env/bin/activate; pip install atheris==2.2.2
 
 run-cairo-compiled-fuzzer:
 	cd fuzzer
 	cargo +nightly fuzz run --fuzz-dir . cairo_compiled_programs_fuzzer
+
+diff-fuzz:
+	. cairo-vm-env/bin/activate ; \
+	cd fuzzer/diff_fuzzer/; \
+	../../cairo-vm-env/bin/python mul_div_mod_hint.py -len_control=0

fuzzer/diff_fuzzer/mul_div_mod_hint.py

@@ -0,0 +1,63 @@
+#!../cairo-vm-env/bin/python3
+import os 
+import sys 
+import subprocess
+import atheris
+
+@atheris.instrument_func
+def generate_limb(fdp):
+    range_check_max = 340282366920938463463374607431768211456 
+    if fdp.ConsumeProbability() > 0.3:
+        return fdp.ConsumeIntInRange(range_check_max >> 1, range_check_max) 
+    elif fdp.ConsumeBool():
+        return fdp.ConsumeIntInRange(0, 10) 
+    else:
+        return fdp.ConsumeIntInRange(0, range_check_max)
+
+@atheris.instrument_func
+def diff_fuzzer(data):
+    fdp = atheris.FuzzedDataProvider(data)
+
+    a_low = generate_limb(fdp)
+    a_high = generate_limb(fdp)
+    b_low = generate_limb(fdp)
+    b_high = generate_limb(fdp)
+    div_low = generate_limb(fdp)
+    div_high = generate_limb(fdp)
+
+    # Ensure div != 0
+    if div_low + div_high == 0:
+        new_limb = fdp.ConsumeIntInRange(1, 340282366920938463463374607431768211456)     
+        if fdp.ConsumeBool():
+            div_low = new_limb
+        else:
+            div_high = new_limb
+
+    with open('uint256_mul_div_mod.json', 'r', encoding='utf-8') as file:
+        data = file.readlines()
+
+    data[331] = '"' + hex(a_low) + '"' + ",\n" 
+    data[333] = '"' + hex(a_high) + '"' + ",\n" 
+    data[335] = '"' + hex(b_low) + '"' + ",\n" 
+    data[337] = '"' + hex(b_high) + '"' + ",\n" 
+    data[339] = '"' + hex(div_low) + '"' + ",\n" 
+    data[341] = '"' + hex(div_high) + '"' + ",\n" 
+
+    filename = hex(fdp.ConsumeUInt(8)) + ".input"
+
+    with open(filename, 'w', encoding='utf-8') as file:
+        file.writelines(data)
+
+    rust_output = subprocess.run(["./../../target/release/cairo-vm-cli", "--layout", "starknet", "--print_output", filename], stdout=subprocess.PIPE)
+    python_output = subprocess.run(["cairo-run", "--layout", "starknet", "--print_output", "--program", filename], stdout=subprocess.PIPE)
+
+    os.remove(filename)
+
+    rust_nums = [int(n) for n in rust_output.stdout.split() if n.isdigit()]
+    python_nums = [int(n) for n in python_output.stdout.split() if n.isdigit()]
+
+    assert rust_nums == python_nums
+
+atheris.Setup(sys.argv, diff_fuzzer)
+atheris.Fuzz()
+