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Fix memory and buffer leaks on error paths #330

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Fix memory and buffer leaks on error paths #330

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fix: release buffers and free memory on error paths 
Fix memory and buffer leaks on five error paths:

- block/compress: release source and dict Py_buffers on PyMem_Malloc failure
- block/decompress: release source and dict Py_buffers on PyMem_Malloc failure
- frame/compress: release source Py_buffer on block_checksum version error
- frame/compress_begin: free destination buffer on LZ4F_compressBegin failure
  (same pattern as the bug fixed in 43fe65d, not propagated to this site)
- frame/__decompress: free original destination buffer on PyMem_Realloc failure
  (realloc returns NULL without freeing the original pointer)

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

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
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@devdanzin @claude
devdanzin and claude committed Apr 1, 2026
commit 5867f192dade717c4bdd1fe63d438dc2548c5b2f
4 changes: 4 additions & 0 deletions lz4/block/_block.c
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Original file line number Diff line number Diff line change
Expand Up @@ -215,6 +215,8 @@ compress (PyObject * Py_UNUSED (self), PyObject * args, PyObject * kwargs)
dest = PyMem_Malloc (total_size * sizeof * dest);
if (dest == NULL)
{
PyBuffer_Release(&source);
PyBuffer_Release(&dict);
return PyErr_NoMemory();
}

Expand Down Expand Up @@ -349,6 +351,8 @@ decompress (PyObject * Py_UNUSED (self), PyObject * args, PyObject * kwargs)
dest = PyMem_Malloc (dest_size * sizeof * dest);
if (dest == NULL)
{
PyBuffer_Release(&source);
PyBuffer_Release(&dict);
return PyErr_NoMemory();
}

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3 changes: 3 additions & 0 deletions lz4/frame/_frame.c
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Original file line number Diff line number Diff line change
Expand Up @@ -184,6 +184,7 @@ compress (PyObject * Py_UNUSED (self), PyObject * args,
}
else if (block_checksum)
{
PyBuffer_Release(&source);
PyErr_SetString (PyExc_RuntimeError,
"block_checksum specified but not supported by LZ4 library version");
return NULL;
Expand Down Expand Up @@ -383,6 +384,7 @@ compress_begin (PyObject * Py_UNUSED (self), PyObject * args,

if (LZ4F_isError (result))
{
PyMem_Free (destination);
PyErr_Format (PyExc_RuntimeError,
"LZ4F_compressBegin failed with code: %s",
LZ4F_getErrorName (result));
Expand Down Expand Up @@ -1115,6 +1117,7 @@ __decompress(LZ4F_dctx * context, char * source, size_t source_size,
buff = PyMem_Realloc (destination, destination_size);
if (buff == NULL)
{
PyMem_Free (destination);
PyErr_SetString (PyExc_RuntimeError,
"Failed to resize buffer");
return NULL;
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