https://github.com/python/cpython/commit/7edb6270a78c695e4c2ae2432797dc18105... commit: 7edb6270a78c695e4c2ae2432797dc18105374fc branch: main author: Ma Lin <animalize@users.noreply.github.com> committer: gpshead <greg@krypto.org> date: 2021-11-26T16:18:17-08:00 summary: bpo-41735: Fix thread lock in zlib.Decompress.flush() may go wrong (GH-29587) * Fix thread lock in zlib.Decompress.flush() may go wrong Getting `.unconsumed_tail` before acquiring the thread lock may mix up decompress state. files: A Misc/NEWS.d/next/Library/2021-11-16-18-13-49.bpo-41735.D72UY1.rst M Modules/zlibmodule.c diff --git a/Misc/NEWS.d/next/Library/2021-11-16-18-13-49.bpo-41735.D72UY1.rst b/Misc/NEWS.d/next/Library/2021-11-16-18-13-49.bpo-41735.D72UY1.rst new file mode 100644 index 0000000000000..101da0e9ce648 --- /dev/null +++ b/Misc/NEWS.d/next/Library/2021-11-16-18-13-49.bpo-41735.D72UY1.rst @@ -0,0 +1 @@ +Fix thread lock in ``zlib.Decompress.flush()`` method before ``PyObject_GetBuffer``. diff --git a/Modules/zlibmodule.c b/Modules/zlibmodule.c index 67bde701fa608..f9646568d7e01 100644 --- a/Modules/zlibmodule.c +++ b/Modules/zlibmodule.c @@ -1269,12 +1269,13 @@ zlib_Decompress_flush_impl(compobject *self, PyTypeObject *cls, return NULL; } + ENTER_ZLIB(self); + if (PyObject_GetBuffer(self->unconsumed_tail, &data, PyBUF_SIMPLE) == -1) { + LEAVE_ZLIB(self); return NULL; } - ENTER_ZLIB(self); - self->zst.next_in = data.buf; ibuflen = data.len;