1## TFSA-2021-132: Reference binding to nullptr in `MatrixSetDiagV*` ops 2 3### CVE Number 4CVE-2021-37658 5 6### Impact 7An attacker can cause undefined behavior via binding a reference to null pointer 8in all operations of type `tf.raw_ops.MatrixSetDiagV*`: 9 10```python 11import tensorflow as tf 12 13tf.raw_ops.MatrixSetDiagV3( 14 input=[1,2,3], 15 diagonal=[1,1], 16 k=[], 17 align='RIGHT_LEFT') 18``` 19 20The 21[implementation](https://github.com/tensorflow/tensorflow/blob/84d053187cb80d975ef2b9684d4b61981bca0c41/tensorflow/core/kernels/linalg/matrix_diag_op.cc) 22has incomplete validation that the value of `k` is a valid tensor. We have check 23that this value is either a scalar or a vector, but there is no check for the 24number of elements. If this is an empty tensor, then code that accesses the 25first element of the tensor is wrong: 26 27```cc 28 auto& diag_index = context->input(1); 29 ... 30 lower_diag_index = diag_index.flat<int32>()(0); 31``` 32 33### Patches 34We have patched the issue in GitHub commit 35[ff8894044dfae5568ecbf2ed514c1a37dc394f1b](https://github.com/tensorflow/tensorflow/commit/ff8894044dfae5568ecbf2ed514c1a37dc394f1b). 36 37The fix will be included in TensorFlow 2.6.0. We will also cherrypick this 38commit on TensorFlow 2.5.1, TensorFlow 2.4.3, and TensorFlow 2.3.4, as these are 39also affected and still in supported range. 40 41### For more information 42Please consult [our security 43guide](https://github.com/tensorflow/tensorflow/blob/master/SECURITY.md) for 44more information regarding the security model and how to contact us with issues 45and questions. 46 47### Attribution 48This vulnerability has been reported by members of the Aivul Team from Qihoo 49360. 50