From b1979d59d6c0783345146847d3753e6125a1c5c7 Mon Sep 17 00:00:00 2001
From: devdanzin <74280297+devdanzin@users.noreply.github.com>
Date: Tue, 31 Mar 2026 23:05:36 -0300
Subject: [PATCH] =?UTF-8?q?fix:=20handle=20module=20init=20errors=20?=
 =?UTF-8?q?=E2=80=94=20decref=20module=20and=20check=20PyModule=5FAddObjec?=
 =?UTF-8?q?t?=
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- Add Py_DECREF(module) before returning NULL when PyErr_NewExceptionWithDoc
  fails in both block and stream module init — previously leaked the module
- Check PyModule_AddObject return value when adding LZ4BlockError and
  LZ4StreamError — previously ignored failures, leaking the exception ref

Found using cext-review-toolkit (https://github.com/devdanzin/cext-review-toolkit).

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
---
 lz4/block/_block.c   | 8 +++++++-
 lz4/stream/_stream.c | 8 +++++++-
 2 files changed, 14 insertions(+), 2 deletions(-)

diff --git a/lz4/block/_block.c b/lz4/block/_block.c
index 993cc44..121143e 100644
--- a/lz4/block/_block.c
+++ b/lz4/block/_block.c
@@ -513,10 +513,16 @@ PyInit__block(void)
   LZ4BlockError = PyErr_NewExceptionWithDoc("_block.LZ4BlockError", "Call to LZ4 library failed.", NULL, NULL);
   if (LZ4BlockError == NULL)
     {
+      Py_DECREF(module);
       return NULL;
     }
   Py_INCREF(LZ4BlockError);
-  PyModule_AddObject(module, "LZ4BlockError", LZ4BlockError);
+  if (PyModule_AddObject(module, "LZ4BlockError", LZ4BlockError) < 0)
+    {
+      Py_DECREF(LZ4BlockError);
+      Py_DECREF(module);
+      return NULL;
+    }
 
   #ifdef Py_GIL_DISABLED
     PyUnstable_Module_SetGIL(module, Py_MOD_GIL_NOT_USED);
diff --git a/lz4/stream/_stream.c b/lz4/stream/_stream.c
index 4c51d89..ccb56d1 100644
--- a/lz4/stream/_stream.c
+++ b/lz4/stream/_stream.c
@@ -1644,10 +1644,16 @@ PyInit__stream(void)
                                               NULL, NULL);
   if (LZ4StreamError == NULL)
     {
+      Py_DECREF (module);
       return NULL;
     }
   Py_INCREF (LZ4StreamError);
-  PyModule_AddObject (module, "LZ4StreamError", LZ4StreamError);
+  if (PyModule_AddObject (module, "LZ4StreamError", LZ4StreamError) < 0)
+    {
+      Py_DECREF (LZ4StreamError);
+      Py_DECREF (module);
+      return NULL;
+    }
 
   #ifdef Py_GIL_DISABLED
     PyUnstable_Module_SetGIL(module, Py_MOD_GIL_NOT_USED);