- Issue python#2586: Fix CVE-2008-1721, zlib crash from

doko42 · doko42 · commit 01feb5ad8d55 · 2008-11-12T07:02:24.000Z
zlib.decompressobj().flush(val) when val is not positive.
diff --git a/Misc/NEWS b/Misc/NEWS
@@ -24,6 +24,9 @@ Core and builtins
 - Issue #1179: Fix CVE-2007-4965 and CVE-2008-1679, multiple integer
   overflows in the imageop and rgbimgmodule modules.
 
+- Issue #2586: Fix CVE-2008-1721, zlib crash from
+  zlib.decompressobj().flush(val) when val is not positive.
+
 Extension Modules
 -----------------
 
diff --git a/Modules/zlibmodule.c b/Modules/zlibmodule.c
@@ -669,6 +669,10 @@ PyZlib_unflush(compobject *self, PyObject *args)
 
     if (!PyArg_ParseTuple(args, "|i:flush", &length))
 	return NULL;
+    if (length <= 0) {
+	PyErr_SetString(PyExc_ValueError, "length must be greater than zero");
+	return NULL;
+    }
     if (!(retval = PyString_FromStringAndSize(NULL, length)))
 	return NULL;
 
