`CHECK`-failures during Grappler's `SafeToRemoveIdentity` in Tensorflow

Impact

The Grappler optimizer in TensorFlow can be used to cause a denial of service by altering a SavedModel such that SafeToRemoveIdentity would trigger CHECK failures.

Patches

We have patched the issue in GitHub commit 92dba16749fae36c246bec3f9ba474d9ddeb7662.
The fix will be included in TensorFlow 2.8.0. We will also cherrypick this commit on TensorFlow 2.7.1, TensorFlow 2.6.3, and TensorFlow 2.5.3, as these are also affected and still in supported range.

For more information

Please consult our security guide for more information regarding the security model and how to contact us with issues and questions.