Issue #24917: time_strftime() Buffer Over-read. Patch by John Leitch.

Misc/NEWS

@@ -84,6 +84,8 @@ Library
 - Issue #16180: Exit pdb if file has syntax error, instead of trapping user
   in an infinite loop.  Patch by Xavier de Gaye.
 
+- Issue #24917: time_strftime() Buffer Over-read. Patch by John Leitch.
+
 - Issue #21112: Fix regression in unittest.expectedFailure on subclasses.
   Patch from Berker Peksag.
 

Modules/timemodule.c

@@ -662,6 +662,12 @@ time_strftime(PyObject *self, PyObject *args)
                             "format %y requires year >= 1900 on AIX");
             return NULL;
         }
+        else if (outbuf[1] == '\0')
+        {
+            PyErr_SetString(PyExc_ValueError, "Incomplete format string");
+            Py_DECREF(format);
+            return NULL;
+        }
     }
 #endif