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bpo-41735: Fix thread locks in zlib module may go wrong in rare case. #22126

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Merged
ambv merged 2 commits into from Apr 27, 2021
Merged

bpo-41735: Fix thread locks in zlib module may go wrong in rare case. #22126

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10a3fa8
Fix thread locks in zlib module may go wrong in rare case.
wjssz Sep 7, 2020
a60b071
Merge branch 'master' into thread_lock
animalize Sep 7, 2020
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1 change: 1 addition & 0 deletions Misc/NEWS.d/next/Library/2020-09-07-11-15-15.bpo-41735.NKqGKy.rst
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Original file line number Diff line number Diff line change
@@ -0,0 +1 @@
Fix thread locks in zlib module may go wrong in rare case. Patch by Ma Lin.
19 changes: 10 additions & 9 deletions Modules/zlibmodule.c
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Expand Up @@ -10,10 +10,12 @@
#include "zlib.h"


#define ENTER_ZLIB(obj) \
Py_BEGIN_ALLOW_THREADS; \
PyThread_acquire_lock((obj)->lock, 1); \
Py_END_ALLOW_THREADS;
#define ENTER_ZLIB(obj) do { \
if (!PyThread_acquire_lock((obj)->lock, 0)) { \
Py_BEGIN_ALLOW_THREADS \
PyThread_acquire_lock((obj)->lock, 1); \
Py_END_ALLOW_THREADS \
} } while (0)
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#define LEAVE_ZLIB(obj) PyThread_release_lock((obj)->lock);

#if defined(ZLIB_VERNUM) && ZLIB_VERNUM >= 0x1221
Expand Down Expand Up @@ -634,14 +636,13 @@ zlib_Compress_compress_impl(compobject *self, PyTypeObject *cls,
PyObject *RetVal = NULL;
Py_ssize_t obuflen = DEF_BUF_SIZE;
int err;

zlibstate *state = PyType_GetModuleState(cls);

ENTER_ZLIB(self);

self->zst.next_in = data->buf;
Py_ssize_t ibuflen = data->len;

ENTER_ZLIB(self);

do {
arrange_input_buffer(&self->zst, &ibuflen);

Expand Down Expand Up @@ -761,15 +762,15 @@ zlib_Decompress_decompress_impl(compobject *self, PyTypeObject *cls,
else
hard_limit = max_length;

ENTER_ZLIB(self);

self->zst.next_in = data->buf;
ibuflen = data->len;

/* limit amount of data allocated to max_length */
if (max_length && obuflen > max_length)
obuflen = max_length;

ENTER_ZLIB(self);

do {
arrange_input_buffer(&self->zst, &ibuflen);

Expand Down