From b43b40298e86797ad82e6bdd205cff8895b47bdf Mon Sep 17 00:00:00 2001 From: Ma Lin Date: Sat, 27 Nov 2021 08:18:17 +0800 Subject: [PATCH] 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. (cherry picked from commit 7edb6270a78c695e4c2ae2432797dc18105374fc) Co-authored-by: Ma Lin --- .../next/Library/2021-11-16-18-13-49.bpo-41735.D72UY1.rst | 1 + Modules/zlibmodule.c | 5 +++-- 2 files changed, 4 insertions(+), 2 deletions(-) create mode 100644 Misc/NEWS.d/next/Library/2021-11-16-18-13-49.bpo-41735.D72UY1.rst 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 00000000000000..101da0e9ce6487 --- /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 68de701efa45f1..a6940f2fd43a3f 100644 --- a/Modules/zlibmodule.c +++ b/Modules/zlibmodule.c @@ -1266,12 +1266,13 @@ 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;