Fix possible integer overflow in lchown and fchown functions. For issue1747858.

Lib/test/test_posix.py

@@ -207,14 +207,8 @@ class PosixTester(unittest.TestCase):
         if hasattr(posix, 'stat'):
             self.assertTrue(posix.stat(test_support.TESTFN))
 
-    if hasattr(posix, 'chown'):
+    def _test_all_chown_common(self, chown_func, first_param):
-        def test_chown(self):
+        """Common code for chown, fchown and lchown tests."""
-            # raise an OSError if the file does not exist
-            os.unlink(test_support.TESTFN)
-            self.assertRaises(OSError, posix.chown, test_support.TESTFN, -1, -1)
-
-            # re-create the file
-            open(test_support.TESTFN, 'w').close()
         if os.getuid() == 0:
             try:
                 # Many linux distros have a nfsnobody user as MAX_UID-2
@@ -223,16 +217,45 @@ class PosixTester(unittest.TestCase):
                 # This part of the test only runs when run as root.
                 # Only scary people run their tests as root.
                 ent = pwd.getpwnam('nfsnobody')
-                    posix.chown(test_support.TESTFN, ent.pw_uid, ent.pw_gid)
+                chown_func(first_param, ent.pw_uid, ent.pw_gid)
             except KeyError:
                 pass
         else:
             # non-root cannot chown to root, raises OSError
-                self.assertRaises(OSError, posix.chown,
+            self.assertRaises(OSError, chown_func,
-                                  test_support.TESTFN, 0, 0)
+                              first_param, 0, 0)
 
         # test a successful chown call
-            posix.chown(test_support.TESTFN, os.getuid(), os.getgid())
+        chown_func(first_param, os.getuid(), os.getgid())
+
+    @unittest.skipUnless(hasattr(posix, 'chown'), "test needs os.chown()")
+    def test_chown(self):
+        # raise an OSError if the file does not exist
+        os.unlink(test_support.TESTFN)
+        self.assertRaises(OSError, posix.chown, test_support.TESTFN, -1, -1)
+
+        # re-create the file
+        open(test_support.TESTFN, 'w').close()
+        self._test_all_chown_common(posix.chown, test_support.TESTFN)
+
+    @unittest.skipUnless(hasattr(posix, 'fchown'), "test needs os.fchown()")
+    def test_fchown(self):
+        os.unlink(test_support.TESTFN)
+
+        # re-create the file
+        test_file = open(test_support.TESTFN, 'w')
+        try:
+            fd = test_file.fileno()
+            self._test_all_chown_common(posix.fchown, fd)
+        finally:
+            test_file.close()
+
+    @unittest.skipUnless(hasattr(posix, 'lchown'), "test needs os.lchown()")
+    def test_lchown(self):
+        os.unlink(test_support.TESTFN)
+        # create a symlink
+        os.symlink('/tmp/dummy-symlink-target', test_support.TESTFN)
+        self._test_all_chown_common(posix.lchown, test_support.TESTFN)
 
     def test_chdir(self):
         if hasattr(posix, 'chdir'):

Modules/posixmodule.c

@@ -1910,9 +1910,10 @@ fd to the numeric uid and gid.");
 static PyObject *
 posix_fchown(PyObject *self, PyObject *args)
 {
-	int fd, uid, gid;
+	int fd;
+	long uid, gid;
 	int res;
-	if (!PyArg_ParseTuple(args, "iii:chown", &fd, &uid, &gid))
+	if (!PyArg_ParseTuple(args, "ill:chown", &fd, &uid, &gid))
 		return NULL;
 	Py_BEGIN_ALLOW_THREADS
 	res = fchown(fd, (uid_t) uid, (gid_t) gid);
@@ -1933,9 +1934,9 @@ static PyObject *
 posix_lchown(PyObject *self, PyObject *args)
 {
 	char *path = NULL;
-	int uid, gid;
+	long uid, gid;
 	int res;
-	if (!PyArg_ParseTuple(args, "etii:lchown",
+	if (!PyArg_ParseTuple(args, "etll:lchown",
 	                      Py_FileSystemDefaultEncoding, &path,
 	                      &uid, &gid))
 		return NULL;