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53 lines
2.1 KiB
Markdown
53 lines
2.1 KiB
Markdown
## TFSA-2020-023: Memory corruption in `dlpack.to_dlpack`
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### CVE Number
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CVE-2020-15193
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### Impact
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The implementation of `dlpack.to_dlpack` can be made to use uninitialized
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memory resulting in further memory corruption. This is because the pybind11
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glue code [assumes that the argument is a
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tensor](https://github.com/tensorflow/tensorflow/blob/0e68f4d3295eb0281a517c3662f6698992b7b2cf/tensorflow/python/tfe_wrapper.cc#L1361):
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```cc
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TFE_TensorHandle* thandle = EagerTensor_Handle(eager_tensor_pyobject_ptr);
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```
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However, there is nothing stopping users from passing in a Python object instead of a tensor.
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```python
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In [2]: tf.experimental.dlpack.to_dlpack([2])
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==1720623==WARNING: MemorySanitizer: use-of-uninitialized-value
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#0 0x55b0ba5c410a in tensorflow::(anonymous namespace)::GetTensorFromHandle(TFE_TensorHandle*, TF_Status*) third_party/tensorflow/c/eager/dlpack.cc:46:7
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#1 0x55b0ba5c38f4 in tensorflow::TFE_HandleToDLPack(TFE_TensorHandle*, TF_Status*) third_party/tensorflow/c/eager/dlpack.cc:252:26
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...
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```
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The uninitialized memory address is due to a
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[`reinterpret_cast`](https://github.com/tensorflow/tensorflow/blob/0e68f4d3295eb0281a517c3662f6698992b7b2cf/tensorflow/python/eager/pywrap_tensor.cc#L848-L850):
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```cc
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TFE_TensorHandle* EagerTensor_Handle(const PyObject* o) {
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return reinterpret_cast<const EagerTensor*>(o)->handle;
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}
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```
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Since the `PyObject` is a Python object, not a TensorFlow Tensor, the cast to `EagerTensor` fails.
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### Vulnerable Versions
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TensorFlow 2.2.0, 2.3.0.
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### Patches
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We have patched the issue in
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[22e07fb204386768e5bcbea563641ea11f96ceb8](https://github.com/tensorflow/tensorflow/commit/22e07fb204386768e5bcbea563641ea11f96ceb8)
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and will release a patch release for all affected versions.
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We recommend users to upgrade to TensorFlow 2.2.1 or 2.3.1.
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### For more information
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Please consult [our security
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guide](https://github.com/tensorflow/tensorflow/blob/master/SECURITY.md) for
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more information regarding the security model and how to contact us with issues
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and questions.
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### Attribution
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This vulnerability has been reported by members of the Aivul Team from Qihoo
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360.
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