Fix for Ctrl-C hang on Python 3.14 (leaked cache locks)

Author: stamparm

lib/core/datatype.py

@@ -9,8 +9,40 @@
 import threading
 
 from collections import OrderedDict
+from thirdparty import six
 from thirdparty.six.moves import collections_abc as _collections
 
+class NoLock(object):
+    """
+    No-op stand-in for a lock, used where the guarded operations are already atomic on their own
+
+    >>> with NoLock():
+    ...     True
+    True
+    """
+
+    def __enter__(self):
+        return self
+
+    def __exit__(self, *args):
+        return False
+
+def cacheLock(reentrant=False):
+    """
+    Returns a lock for guarding the (OrderedDict based) caches. Only Python 2 needs a real one, as its
+    OrderedDict is implemented in Python (#5619), while on Python 3 each operation is atomic. Moreover,
+    since Python 3.14 a Ctrl-C landing right after a lock got acquired by the 'with' statement leaves it
+    acquired forever (i.e. '__exit__' never gets called), hanging every thread that touches the cache
+
+    >>> isinstance(cacheLock(), NoLock) == six.PY3
+    True
+    """
+
+    if six.PY2:
+        return threading.RLock() if reentrant else threading.Lock()
+    else:
+        return NoLock()
+
 class AttribDict(dict):
     """
     This class defines the dictionary with added capability to access members as attributes
@@ -133,7 +165,7 @@ class LRUDict(object):
     def __init__(self, capacity):
         self.capacity = capacity
         self.cache = OrderedDict()
-        self.__lock = threading.Lock()
+        self.__lock = cacheLock()
 
     def __len__(self):
         return len(self.cache)
@@ -159,7 +191,10 @@ def __setitem__(self, key, value):
                 self.cache.pop(key)
             except KeyError:
                 if len(self.cache) >= self.capacity:
-                    self.cache.popitem(last=False)
+                    try:
+                        self.cache.popitem(last=False)
+                    except KeyError:    # Note: concurrently emptied by another thread (unlocked on Python 3)
+                        pass
             self.cache[key] = value
 
     def set(self, key, value):

lib/core/decorators.py

@@ -9,6 +9,7 @@
 import threading
 
 from lib.core.datatype import LRUDict
+from lib.core.datatype import cacheLock
 from lib.core.settings import MAX_CACHE_ITEMS
 from lib.core.threads import getCurrentThreadData
 
@@ -40,7 +41,7 @@ def cachedmethod(f):
     """
 
     _cache[f] = LRUDict(capacity=MAX_CACHE_ITEMS)
-    _method_locks[f] = threading.RLock()
+    _method_locks[f] = cacheLock(reentrant=True)
 
     def _freeze(val):
         if isinstance(val, (list, set, tuple)):
@@ -60,8 +61,10 @@ def _f(*args, **kwargs):
                 key = args
 
             with lock:
-                if key in cache:
+                try:
                     return cache[key]
+                except KeyError:        # Note: single lookup, as an entry can get evicted in between (unlocked on Python 3)
+                    pass
 
         except TypeError:
             # Note: fallback (slow-path) for unhashable arguments
@@ -72,8 +75,10 @@ def _f(*args, **kwargs):
                     key = (_FROZEN_KEY_MARKER, _freeze(args))
 
                 with lock:
-                    if key in cache:
+                    try:
                         return cache[key]
+                    except KeyError:
+                        pass
             except TypeError:
                 # Note: genuinely uncacheable arguments; skip caching altogether
                 return f(*args, **kwargs)

lib/core/settings.py

@@ -19,7 +19,7 @@
 from thirdparty import six
 
 # sqlmap version (<major>.<minor>.<month>.<monthly commit>)
-VERSION = "1.10.10.24"
+VERSION = "1.10.10.25"
 TYPE = "dev" if VERSION.count('.') > 2 and VERSION.split('.')[-1] != '0' else "stable"
 TYPE_COLORS = {"dev": 33, "stable": 90, "pip": 34}
 VERSION_STRING = "sqlmap/%s#%s" % ('.'.join(VERSION.split('.')[:-1]) if VERSION.count('.') > 2 and VERSION.split('.')[-1] == '0' else VERSION, TYPE)