commit 796cc6e3ad3617c1ea9e528663aac1a206230a28
author Thomas Perl <m@thp.io> Thu Mar 28 07:03:25 2019 +0100
committer Inada Naoki <songofacandy@gmail.com> Thu Mar 28 15:03:25 2019 +0900
tree 0af419b927af85d970dc7f1c207e04a1744704cd
parent 738cb42a14481aa9ae58704f6bee951308212d7e

bpo-36452: dictiter: track maximum iteration count (GH-12596)

Objects/dictobject.c

diff --git a/Objects/dictobject.c b/Objects/dictobject.c
index e2603e1..7ea979c 100644
--- a/Objects/dictobject.c
+++ b/Objects/dictobject.c
@@ -3543,6 +3543,12 @@
             goto fail;
         key = entry_ptr->me_key;
     }
+    // We found an element (key), but did not expect it
+    if (di->len == 0) {
+        PyErr_SetString(PyExc_RuntimeError,
+                        "dictionary keys changed during iteration");
+        goto fail;
+    }
     di->di_pos = i+1;
     di->len--;
     Py_INCREF(key);