CVE-2021-37657: Access of Uninitialized Pointer (CWE-824)
value: TensorFlow is an end-to-end open source platform for machine learning. In affected versions an attacker can cause undefined behavior via binding a reference to null pointer in all operations of type `tf.raw_ops.MatrixDiagV*`. The [implementation](https://github.com/tensorflow/tensorflow/blob/84d053187cb80d975ef2b9684d4b61981bca0c41/tensorflow/core/kernels/linalg/matrix_diag_op.cc) has incomplete validation that the value of `k` is a valid tensor. We have check that this value is either a scalar or a vector, but there is no check for the number of elements. If this is an empty tensor, then code that accesses the first element of the tensor is wrong. We have patched the issue in GitHub commit f2a673bd34f0d64b8e40a551ac78989d16daad09. The fix will be included in TensorFlow 2.6.0. We will also cherrypick this commit on TensorFlow 2.5.1, TensorFlow 2.4.3, and TensorFlow 2.3.4, as these are also affected and still in supported range.
CWE description: The product accesses or uses a pointer that has not been initialized.
CVSS v3 base score: 7.8
Published: 2021-08-12T21:15Z
Repository: https://github.com/tensorflow/tensorflow
Language: C++
Files changed: tensorflow/core/kernels/linalg/matrix_diag_op.cc
Commit date: 2021-07-30 19:12:41 -0700
Commit message: Add missing validation to `matrix_diag_op.cc`

PiperOrigin-RevId: 387923533
Change-Id: Idfffeb328d5f9c6748d992d28a56d6e9e45103a0

Diff: diff --git a/tensorflow/core/kernels/linalg/matrix_diag_op.cc b/tensorflow/core/kernels/linalg/matrix_diag_op.cc
index 2fd361e715b9b..b61dbe96a5d6a 100644
--- a/tensorflow/core/kernels/linalg/matrix_diag_op.cc
+++ b/tensorflow/core/kernels/linalg/matrix_diag_op.cc
@@ -71,10 +71,13 @@ class MatrixDiagPartOp : public OpKernel {
                   TensorShapeUtils::IsScalar(diag_index.shape()) ||
                       TensorShapeUtils::IsVector(diag_index.shape()),
                   errors::InvalidArgument(
                       "diag_index must be a scalar or vector, received shape: ",
                       diag_index.shape().DebugString()));
+      OP_REQUIRES(context, diag_index.NumElements() > 0,
+                  errors::InvalidArgument(
+                      "Expected diag_index to have at least 1 element"));
       lower_diag_index = diag_index.flat<int32>()(0);
       upper_diag_index = lower_diag_index;
       if (TensorShapeUtils::IsVector(diag_index.shape())) {
         auto diag_index_size = diag_index.dim_size(0);
         OP_REQUIRES(
@@ -177,10 +180,13 @@ class MatrixDiagOp : public OpKernel {
                   TensorShapeUtils::IsScalar(diag_index.shape()) ||
                       TensorShapeUtils::IsVector(diag_index.shape()),
                   errors::InvalidArgument(
                       "diag_index must be a scalar or vector, received shape: ",
                       diag_index.shape().DebugString()));
+      OP_REQUIRES(context, diag_index.NumElements() > 0,
+                  errors::InvalidArgument(
+                      "Expected diag_index to have at least 1 element"));
       lower_diag_index = diag_index.flat<int32>()(0);
       upper_diag_index = lower_diag_index;
       if (TensorShapeUtils::IsVector(diag_index.shape())) {
         auto diag_index_size = diag_index.dim_size(0);
         OP_REQUIRES(

Fixed code:       OP_REQUIRES(context, diag_index.NumElements() > 0,
                  errors::InvalidArgument(
                      "Expected diag_index to have at least 1 element"));
      OP_REQUIRES(context, diag_index.NumElements() > 0,
                  errors::InvalidArgument(
                      "Expected diag_index to have at least 1 element"));