Incomplete validation in `tf.raw_ops.CTCLoss`
ImpactIncomplete validation in `tf.raw_ops.CTCLoss` allows an attacker to trigger an OOB read from heap:An attacker can also trigger a heap buffer overflow:Finally, an attacker can trigger a null pointer dereference:PatchesWe have patched the issue in GitHub commit[14607c0707040d775e06b6817325640cb4b5864c](https://github.com/tensorflow/tensorflow/commit/14607c0707040d775e06b6817325640cb4b5864c) followed by GitHub commit [4504a081af71514bb1828048363e6540f797005b](https://github.com/tensorflow/tensorflow/commit/4504a081af71514bb1828048363e6540f797005b).The fix will be included in TensorFlow 2.5.0. We will also cherrypick these commits on TensorFlow 2.4.2, TensorFlow 2.3.3, TensorFlow 2.2.3 and TensorFlow 2.1.4, as these are also affected and still in supported range.For more informationPlease 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.AttributionThis vulnerability has been reported by Yakun Zhang and Ying Wang of Baidu X-Team.