GHSA-gwcx-jrx4-92w2

Segfault in `simplifyBroadcast` in Tensorflow

### Impact The [`simplifyBroadcast` function in the MLIR-TFRT infrastructure in TensorFlow](https://github.com/tensorflow/tensorflow/blob/274df9b02330b790aa8de1cee164b70f72b9b244/tensorflow/compiler/mlir/tfrt/jit/transforms/tf_cpurt_symbolic_shape_optimization.cc#L149-L205) is vulnerable to a segfault (hence, denial of service), if called with scalar shapes. ```cc size_t maxRank = 0; for (auto shape : llvm::enumerate(shapes)) { auto found_shape = analysis.dimensionsForShapeTensor(shape.value()); if (!found_shape) return {}; shapes_found.push_back(*found_shape); maxRank = std::max(maxRank, found_shape->size()); } SmallVector<const ShapeComponentAnalysis::SymbolicDimension*> joined_dimensions(maxRank); ``` If all shapes are scalar, then `maxRank` is 0, so we build an empty `SmallVector`. ### Patches We have patched the issue in GitHub commit [35f0fabb4c178253a964d7aabdbb15c6a398b69a](https://github.com/tensorflow/tensorflow/commit/35f0fabb4c178253a964d7aabdbb15c6a398b69a). The fix will be included in TensorFlow 2.8.0. This is the only affected version. ### For more information Please consult [our security guide](https://github.com/tensorflow/tensorflow/blob/master/SECURITY.md) for more information regarding the security model and how to contact us with issues and questions.