From 39de95b746c990e6a2fe9af5fad01747f58b2e5f Mon Sep 17 00:00:00 2001 From: Benjamin Peterson Date: Thu, 12 Sep 2019 00:43:22 +0100 Subject: [PATCH] closes bpo-38124: Fix bounds check in PyState_AddModule. (GH-16007) The >=, checking whether a module index was in already in the module-by-index list, needed to be strict. Also, fold nested ifs into one and fix some bad spacing. --- .../2019-09-12-00-14-01.bpo-38124.n6E0H7.rst | 2 ++ Python/pystate.c | 14 ++++++-------- 2 files changed, 8 insertions(+), 8 deletions(-) create mode 100644 Misc/NEWS.d/next/Core and Builtins/2019-09-12-00-14-01.bpo-38124.n6E0H7.rst diff --git a/Misc/NEWS.d/next/Core and Builtins/2019-09-12-00-14-01.bpo-38124.n6E0H7.rst b/Misc/NEWS.d/next/Core and Builtins/2019-09-12-00-14-01.bpo-38124.n6E0H7.rst new file mode 100644 index 0000000000..dca0ba5bc0 --- /dev/null +++ b/Misc/NEWS.d/next/Core and Builtins/2019-09-12-00-14-01.bpo-38124.n6E0H7.rst @@ -0,0 +1,2 @@ +Fix an off-by-one error in PyState_AddModule that could cause out-of-bounds +memory access. diff --git a/Python/pystate.c b/Python/pystate.c index 02bc903943..7dd8b7f866 100644 --- a/Python/pystate.c +++ b/Python/pystate.c @@ -684,7 +684,7 @@ _PyState_AddModule(PyObject* module, struct PyModuleDef* def) if (!state->modules_by_index) return -1; } - while(PyList_GET_SIZE(state->modules_by_index) <= def->m_base.m_index) + while (PyList_GET_SIZE(state->modules_by_index) <= def->m_base.m_index) if (PyList_Append(state->modules_by_index, Py_None) < 0) return -1; Py_INCREF(module); @@ -702,13 +702,11 @@ PyState_AddModule(PyObject* module, struct PyModuleDef* def) return -1; } index = def->m_base.m_index; - if (state->modules_by_index) { - if(PyList_GET_SIZE(state->modules_by_index) >= index) { - if(module == PyList_GET_ITEM(state->modules_by_index, index)) { - Py_FatalError("PyState_AddModule: Module already added!"); - return -1; - } - } + if (state->modules_by_index && + index < PyList_GET_SIZE(state->modules_by_index) && + module == PyList_GET_ITEM(state->modules_by_index, index)) { + Py_FatalError("PyState_AddModule: Module already added!"); + return -1; } return _PyState_AddModule(module, def); } -- 2.40.0