From 911933704e90681bfc0860e32ed5f0f1219246b5 Mon Sep 17 00:00:00 2001 From: Anthony Baxter Date: Tue, 30 Apr 2002 04:05:33 +0000 Subject: [PATCH] backport tim_one's patch: Repair widespread misuse of _PyString_Resize. Since it's clear people don't understand how this function works, also beefed up the docs. The most common usage error is of this form (often spread out across gotos): if (_PyString_Resize(&s, n) < 0) { Py_DECREF(s); s = NULL; goto outtahere; } The error is that if _PyString_Resize runs out of memory, it automatically decrefs the input string object s (which also deallocates it, since its refcount must be 1 upon entry), and sets s to NULL. So if the "if" branch ever triggers, it's an error to call Py_DECREF(s): s is already NULL! A correct way to write the above is the simpler (and intended) if (_PyString_Resize(&s, n) < 0) goto outtahere; Bugfix candidate. Original patch(es): python/dist/src/Python/bltinmodule.c:2.253 --- Python/bltinmodule.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/Python/bltinmodule.c b/Python/bltinmodule.c index 03b941828b99..d002d5895406 100644 --- a/Python/bltinmodule.c +++ b/Python/bltinmodule.c @@ -2000,8 +2000,8 @@ filterstring(PyObject *func, PyObject *strobj) Py_DECREF(item); } - if (j < len && _PyString_Resize(&result, j) < 0) - return NULL; + if (j < len) + _PyString_Resize(&result, j); return result; -- 2.47.3