From ebf650532b41f5e64a5620b8e47acc3a99555e14 Mon Sep 17 00:00:00 2001 From: "Miss Islington (bot)" <31488909+miss-islington@users.noreply.github.com> Date: Sun, 24 May 2020 07:43:02 -0700 Subject: bpo-40705: Fix use-after-free in _zoneinfo's module_free (GH-20280) (cherry picked from commit 06a1b8915d6674e40f0dccc422ca2c06212392d8) Co-authored-by: Ammar Askar --- Modules/_zoneinfo.c | 15 +++++++++------ 1 file changed, 9 insertions(+), 6 deletions(-) diff --git a/Modules/_zoneinfo.c b/Modules/_zoneinfo.c index d7e7157..d852c76 100644 --- a/Modules/_zoneinfo.c +++ b/Modules/_zoneinfo.c @@ -2490,6 +2490,7 @@ new_weak_cache() static int initialize_caches() { + // TODO: Move to a PyModule_GetState / PEP 573 based caching system. if (TIMEDELTA_CACHE == NULL) { TIMEDELTA_CACHE = PyDict_New(); } @@ -2603,14 +2604,16 @@ module_free() xdecref_ttinfo(&NO_TTINFO); - Py_XDECREF(TIMEDELTA_CACHE); - if (!Py_REFCNT(TIMEDELTA_CACHE)) { - TIMEDELTA_CACHE = NULL; + if (TIMEDELTA_CACHE != NULL && Py_REFCNT(TIMEDELTA_CACHE) > 1) { + Py_DECREF(TIMEDELTA_CACHE); + } else { + Py_CLEAR(TIMEDELTA_CACHE); } - Py_XDECREF(ZONEINFO_WEAK_CACHE); - if (!Py_REFCNT(ZONEINFO_WEAK_CACHE)) { - ZONEINFO_WEAK_CACHE = NULL; + if (ZONEINFO_WEAK_CACHE != NULL && Py_REFCNT(ZONEINFO_WEAK_CACHE) > 1) { + Py_DECREF(ZONEINFO_WEAK_CACHE); + } else { + Py_CLEAR(ZONEINFO_WEAK_CACHE); } strong_cache_free(ZONEINFO_STRONG_CACHE); -- cgit v0.12