Add fuzzer for json_encode module

Makefile

@@ -1,8 +1,8 @@
-all : fuzzer-html fuzzer-email fuzzer-httpclient fuzzer-json fuzzer-difflib fuzzer-csv fuzzer-decode fuzzer-ast fuzzer-tarfile fuzzer-tarfile-hypothesis fuzzer-zipfile fuzzer-zipfile-hypothesis fuzzer-re fuzzer-configparser fuzzer-tomllib fuzzer-plistlib fuzzer-xml fuzzer-zoneinfo
+all : fuzzer-html fuzzer-email fuzzer-httpclient fuzzer-json fuzzer-difflib fuzzer-csv fuzzer-decode fuzzer-ast fuzzer-tarfile fuzzer-tarfile-hypothesis fuzzer-zipfile fuzzer-zipfile-hypothesis fuzzer-re fuzzer-configparser fuzzer-tomllib fuzzer-plistlib fuzzer-xml fuzzer-zoneinfo fuzzer-json-encode
 
 PYTHON_CONFIG_PATH=$(CPYTHON_INSTALL_PATH)/bin/python3-config
 CXXFLAGS += $(shell $(PYTHON_CONFIG_PATH) --cflags)
-LDFLAGS += -rdynamic $(shell $(PYTHON_CONFIG_PATH) --ldflags --embed)
+LDFLAGS += -rdynamic $(shell $(PYTHON_CONFIG_PATH) --ldflags --embed) $(CPYTHON_MODLIBS) -Wl,--allow-multiple-definition
 
 fuzzer-html:
 	clang++ $(CXXFLAGS) $(LIB_FUZZING_ENGINE) -std=c++17 fuzzer.cpp -DPYTHON_HARNESS_PATH="\"html.py\"" -ldl $(LDFLAGS) -o fuzzer-html
@@ -40,3 +40,6 @@ fuzzer-xml:
 	clang++ $(CXXFLAGS) $(LIB_FUZZING_ENGINE) -std=c++17 fuzzer.cpp -DPYTHON_HARNESS_PATH="\"xml.py\"" -ldl $(LDFLAGS) -o fuzzer-xml
 fuzzer-zoneinfo:
 	clang++ $(CXXFLAGS) $(LIB_FUZZING_ENGINE) -std=c++17 fuzzer.cpp -DPYTHON_HARNESS_PATH="\"zoneinfo.py\"" -ldl $(LDFLAGS) -o fuzzer-zoneinfo
+
+fuzzer-json-encode:
+	clang++ $(CXXFLAGS) $(LIB_FUZZING_ENGINE) -std=c++17 fuzzer.cpp -DPYTHON_HARNESS_PATH="\"json_encode.py\"" -ldl $(LDFLAGS) -o fuzzer-json-encode

fuzz_targets.txt

@@ -7,6 +7,7 @@ email email.py
 html html.py
 httpclient httpclient.py
 json json.py
+json-encode json_encode.py
 plistlib plist.py
 re re.py
 tarfile tarfile.py

json_encode.py

@@ -0,0 +1,86 @@
+from fuzzeddataprovider import FuzzedDataProvider
+import json
+
+# Container type constants for build_container
+CONTAINER_INT_LIST = 0
+CONTAINER_STRING = 1
+CONTAINER_DICT = 2
+CONTAINER_TUPLE = 3
+CONTAINER_FLOAT = 4
+CONTAINER_INT = 5
+
+# Encode operation constants for FuzzerRunOne
+ENCODE_DEFAULT = 0
+ENCODE_ASCII = 1
+ENCODE_NON_ASCII = 2
+ENCODE_SORTED = 3
+ENCODE_INDENTED = 4
+ENCODE_CUSTOM = 5
+
+
+def build_container(fdp):
+    ctype = fdp.ConsumeIntInRange(CONTAINER_INT_LIST, CONTAINER_INT)
+    if ctype == CONTAINER_INT_LIST:
+        n = fdp.ConsumeIntInRange(0, min(fdp.remaining_bytes(), 200))
+        return fdp.ConsumeIntList(n, 1)
+    elif ctype == CONTAINER_STRING:
+        n = (
+            fdp.ConsumeIntInRange(1, min(fdp.remaining_bytes(), 1000))
+            if fdp.remaining_bytes() > 0
+            else 0
+        )
+        return fdp.ConsumeBytes(n).decode("latin-1") if n > 0 else ""
+    elif ctype == CONTAINER_DICT:
+        n = fdp.ConsumeIntInRange(0, min(fdp.remaining_bytes(), 50))
+        d = {}
+        for _ in range(n):
+            if fdp.remaining_bytes() == 0:
+                break
+            kn = fdp.ConsumeIntInRange(1, min(fdp.remaining_bytes(), 20))
+            key = fdp.ConsumeBytes(kn).decode("latin-1")
+            val = fdp.ConsumeRandomValue()
+            d[key] = val
+        return d
+    elif ctype == CONTAINER_TUPLE:
+        n = fdp.ConsumeIntInRange(0, min(fdp.remaining_bytes(), 200))
+        return tuple(fdp.ConsumeIntList(n, 1))
+    elif ctype == CONTAINER_FLOAT:
+        return fdp.ConsumeFloat()
+    else:
+        return fdp.ConsumeInt(4)
+
+
+# Fuzzes the _json C module's encoding paths (Modules/_json.c).
+# Builds Python containers (int lists, string dicts, tuples, floats)
+# from fuzzed data and encodes them with json.dumps() using varied
+# options (ensure_ascii, sort_keys, indent) and custom JSONEncoder
+# settings (separators, allow_nan, default handler).
+def FuzzerRunOne(FuzzerInput):
+    if len(FuzzerInput) < 1 or len(FuzzerInput) > 0x100000:
+        return
+    fdp = FuzzedDataProvider(FuzzerInput)
+    target = fdp.ConsumeIntInRange(ENCODE_DEFAULT, ENCODE_CUSTOM)
+    try:
+        obj = build_container(fdp)
+        if target == ENCODE_DEFAULT:
+            json.dumps(obj)
+        elif target == ENCODE_ASCII:
+            json.dumps(obj, ensure_ascii=True)
+        elif target == ENCODE_NON_ASCII:
+            json.dumps(obj, ensure_ascii=False)
+        elif target == ENCODE_SORTED:
+            json.dumps(obj, sort_keys=True)
+        elif target == ENCODE_INDENTED:
+            indent = fdp.ConsumeIntInRange(0, 8)
+            json.dumps(obj, indent=indent)
+        else:
+            enc = json.JSONEncoder(
+                ensure_ascii=fdp.ConsumeBool(),
+                sort_keys=fdp.ConsumeBool(),
+                indent=fdp.ConsumeIntInRange(0, 4) if fdp.ConsumeBool() else None,
+            )
+            enc.encode(obj)
+    except (ValueError, TypeError, RecursionError, OverflowError):
+        pass
+    except Exception:
+        pass