Fix potential leaks for interrupted dlpack capsule creation

cuda_core/cuda/core/experimental/_dlpack.pyx

@@ -26,49 +26,54 @@ cdef void pycapsule_deleter(object capsule) noexcept:
 
 
 cdef void deleter(DLManagedTensor* tensor) noexcept with gil:
-    stdlib.free(tensor.dl_tensor.shape)
-    if tensor.manager_ctx:
-        cpython.Py_DECREF(<object>tensor.manager_ctx)
-        tensor.manager_ctx = NULL
-    stdlib.free(tensor)
+    if tensor:
+        if tensor.dl_tensor.shape:
+            stdlib.free(tensor.dl_tensor.shape)
+        if tensor.manager_ctx:
+            cpython.Py_DECREF(<object>tensor.manager_ctx)
+            tensor.manager_ctx = NULL
+        stdlib.free(tensor)
 
 
 cdef void versioned_deleter(DLManagedTensorVersioned* tensor) noexcept with gil:
-    stdlib.free(tensor.dl_tensor.shape)
-    if tensor.manager_ctx:
-        cpython.Py_DECREF(<object>tensor.manager_ctx)
-        tensor.manager_ctx = NULL
-    stdlib.free(tensor)
-
-
-cpdef object make_py_capsule(object buf, bint versioned):
-    cdef DLManagedTensor* dlm_tensor
-    cdef DLManagedTensorVersioned* dlm_tensor_ver
-    cdef DLTensor* dl_tensor
-    cdef void* tensor_ptr
-    cdef const char* capsule_name
-
-    if versioned:
+    if tensor:
+        if tensor.dl_tensor.shape:
+            stdlib.free(tensor.dl_tensor.shape)
+        if tensor.manager_ctx:
+            cpython.Py_DECREF(<object>tensor.manager_ctx)
+            tensor.manager_ctx = NULL
+        stdlib.free(tensor)
+
+
+cdef inline DLManagedTensorVersioned* allocate_dlm_tensor_versioned() except? NULL:
+    cdef DLManagedTensorVersioned* dlm_tensor_ver = NULL
+    try:
         dlm_tensor_ver = <DLManagedTensorVersioned*>(
             stdlib.malloc(sizeof(DLManagedTensorVersioned)))
-        dlm_tensor_ver.version.major = DLPACK_MAJOR_VERSION
-        dlm_tensor_ver.version.minor = DLPACK_MINOR_VERSION
-        dlm_tensor_ver.manager_ctx = <void*>buf
-        dlm_tensor_ver.deleter = versioned_deleter
-        dlm_tensor_ver.flags = 0
-        dl_tensor = &dlm_tensor_ver.dl_tensor
-        tensor_ptr = dlm_tensor_ver
-        capsule_name = DLPACK_VERSIONED_TENSOR_UNUSED_NAME
-    else:
+        dlm_tensor_ver.dl_tensor.shape = NULL
+        dlm_tensor_ver.manager_ctx = NULL
+        return dlm_tensor_ver
+    except:
+        if dlm_tensor_ver:
+            stdlib.free(dlm_tensor_ver)
+        raise
+
+
+cdef inline DLManagedTensor* allocate_dlm_tensor() except? NULL:
+    cdef DLManagedTensor* dlm_tensor = NULL
+    try:
         dlm_tensor = <DLManagedTensor*>(
             stdlib.malloc(sizeof(DLManagedTensor)))
-        dl_tensor = &dlm_tensor.dl_tensor
-        dlm_tensor.manager_ctx = <void*>buf
-        dlm_tensor.deleter = deleter
-        tensor_ptr = dlm_tensor
-        capsule_name = DLPACK_TENSOR_UNUSED_NAME
+        dlm_tensor.dl_tensor.shape = NULL
+        dlm_tensor.manager_ctx = NULL
+        return dlm_tensor
+    except:
+        if dlm_tensor:
+            stdlib.free(dlm_tensor)
+        raise
 
-    dl_tensor.data = <void*><intptr_t>(int(buf.handle))
+
+cdef inline int setup_dl_tensor_layout(DLTensor* dl_tensor, object buf) except -1:
     dl_tensor.ndim = 1
     cdef int64_t* shape_strides = \
         <int64_t*>stdlib.malloc(sizeof(int64_t) * 2)
@@ -77,7 +82,10 @@ cpdef object make_py_capsule(object buf, bint versioned):
     dl_tensor.shape = shape_strides
     dl_tensor.strides = NULL
     dl_tensor.byte_offset = 0
+    return 0
+
 
+cdef inline int setup_dl_tensor_device(DLTensor* dl_tensor, object buf) except -1:
     cdef DLDevice* device = &dl_tensor.device
     # buf should be a Buffer instance
     if buf.is_device_accessible and not buf.is_host_accessible:
@@ -91,14 +99,59 @@ cpdef object make_py_capsule(object buf, bint versioned):
         device.device_id = 0
     else:  # not buf.is_device_accessible and not buf.is_host_accessible
         raise BufferError("invalid buffer")
+    return 0
 
+
+cdef inline int setup_dl_tensor_dtype(DLTensor* dl_tensor) except -1 nogil:
     cdef DLDataType* dtype = &dl_tensor.dtype
     dtype.code = <uint8_t>kDLInt
     dtype.lanes = <uint16_t>1
     dtype.bits = <uint8_t>8
+    return 0
+
 
-    cpython.Py_INCREF(buf)
-    return cpython.PyCapsule_New(tensor_ptr, capsule_name, pycapsule_deleter)
+cpdef object make_py_capsule(object buf, bint versioned):
+    cdef DLManagedTensor* dlm_tensor = NULL
+    cdef DLManagedTensorVersioned* dlm_tensor_ver = NULL
+    cdef DLTensor* dl_tensor
+    cdef void* tensor_ptr
+    cdef const char* capsule_name
+    cdef object ret = None
+
+    try:
+        if versioned:
+            dlm_tensor_ver = allocate_dlm_tensor_versioned()
+            # Transfer the reference to manager_ctx
+            cpython.Py_INCREF(buf)
+            dlm_tensor_ver.manager_ctx = <void*>buf
+            dlm_tensor_ver.deleter = versioned_deleter
+            dlm_tensor_ver.version.major = DLPACK_MAJOR_VERSION
+            dlm_tensor_ver.version.minor = DLPACK_MINOR_VERSION
+            dlm_tensor_ver.flags = 0
+            dl_tensor = &dlm_tensor_ver.dl_tensor
+            tensor_ptr = dlm_tensor_ver
+            capsule_name = DLPACK_VERSIONED_TENSOR_UNUSED_NAME
+        else:
+            dlm_tensor = allocate_dlm_tensor()
+            # Transfer the reference to manager_ctx
+            cpython.Py_INCREF(buf)
+            dlm_tensor.manager_ctx = <void*>buf
+            dlm_tensor.deleter = deleter
+            dl_tensor = &dlm_tensor.dl_tensor
+            tensor_ptr = dlm_tensor
+            capsule_name = DLPACK_TENSOR_UNUSED_NAME
+
+        dl_tensor.data = <void*><intptr_t>(int(buf.handle))
+        setup_dl_tensor_layout(dl_tensor, buf)
+        setup_dl_tensor_device(dl_tensor, buf)
+        setup_dl_tensor_dtype(dl_tensor)
+        ret = cpython.PyCapsule_New(tensor_ptr, capsule_name, pycapsule_deleter)
+    except:
+        if ret is None:
+            deleter(dlm_tensor)
+            versioned_deleter(dlm_tensor_ver)
+        raise
+    return ret
 
 
 class DLDeviceType(IntEnum):

cuda_core/tests/test_memory.py

@@ -278,6 +278,19 @@ def test_buffer_dunder_dlpack_device_failure():
         buffer.__dlpack_device__()
 
 
+def test_buffer_dlpack_failure_clean_up():
+    dummy_mr = NullMemoryResource()
+    buffer = dummy_mr.allocate(size=1024)
+    before = sys.getrefcount(buffer)
+    with pytest.raises(BufferError, match="invalid buffer"):
+        buffer.__dlpack__()
+    after = sys.getrefcount(buffer)
+    # we use the buffer refcount as sentinel for proper clean-up here,
+    # hoping that malloc and frees did the right thing
+    # as they are handled by the same deleter
+    assert after == before
+
+
 @pytest.mark.parametrize("use_device_object", [True, False])
 def test_device_memory_resource_initialization(use_device_object):
     """Test that DeviceMemoryResource can be initialized successfully.