bpo-22689: Copy the result of getenv() in sys_breakpointhook(). (GH-8194)
(cherry picked from commit f60bf0e168255b7675a4c049250ba6b202f8e647)
Co-authored-by: Serhiy Storchaka <storchaka@gmail.com>
diff --git a/Python/sysmodule.c b/Python/sysmodule.c
index d68572d..498fa91 100644
--- a/Python/sysmodule.c
+++ b/Python/sysmodule.c
@@ -107,7 +107,7 @@
sys_breakpointhook(PyObject *self, PyObject *const *args, Py_ssize_t nargs, PyObject *keywords)
{
assert(!PyErr_Occurred());
- const char *envar = Py_GETENV("PYTHONBREAKPOINT");
+ char *envar = Py_GETENV("PYTHONBREAKPOINT");
if (envar == NULL || strlen(envar) == 0) {
envar = "pdb.set_trace";
@@ -116,6 +116,15 @@
/* The breakpoint is explicitly no-op'd. */
Py_RETURN_NONE;
}
+ /* According to POSIX the string returned by getenv() might be invalidated
+ * or the string content might be overwritten by a subsequent call to
+ * getenv(). Since importing a module can performs the getenv() calls,
+ * we need to save a copy of envar. */
+ envar = _PyMem_RawStrdup(envar);
+ if (envar == NULL) {
+ PyErr_NoMemory();
+ return NULL;
+ }
const char *last_dot = strrchr(envar, '.');
const char *attrname = NULL;
PyObject *modulepath = NULL;
@@ -131,12 +140,14 @@
attrname = last_dot + 1;
}
if (modulepath == NULL) {
+ PyMem_RawFree(envar);
return NULL;
}
PyObject *fromlist = Py_BuildValue("(s)", attrname);
if (fromlist == NULL) {
Py_DECREF(modulepath);
+ PyMem_RawFree(envar);
return NULL;
}
PyObject *module = PyImport_ImportModuleLevelObject(
@@ -154,6 +165,7 @@
if (hook == NULL) {
goto error;
}
+ PyMem_RawFree(envar);
PyObject *retval = _PyObject_FastCallKeywords(hook, args, nargs, keywords);
Py_DECREF(hook);
return retval;
@@ -164,6 +176,7 @@
int status = PyErr_WarnFormat(
PyExc_RuntimeWarning, 0,
"Ignoring unimportable $PYTHONBREAKPOINT: \"%s\"", envar);
+ PyMem_RawFree(envar);
if (status < 0) {
/* Printing the warning raised an exception. */
return NULL;