Heap buffer overflow in `MaxPool3DGradGrad`

Impact

The implementation of tf.raw_ops.MaxPool3DGradGrad is vulnerable to a heap buffer overflow:

import tensorflow as tf

values = [0.01] * 11
orig_input = tf.constant(values, shape=[11, 1, 1, 1, 1], dtype=tf.float32)
orig_output = tf.constant([0.01], shape=[1, 1, 1, 1, 1], dtype=tf.float32)
grad = tf.constant([0.01], shape=[1, 1, 1, 1, 1], dtype=tf.float32)
ksize = [1, 1, 1, 1, 1]
strides = [1, 1, 1, 1, 1]
padding = "SAME"

tf.raw_ops.MaxPool3DGradGrad(
    orig_input=orig_input, orig_output=orig_output, grad=grad, ksize=ksize,
    strides=strides, padding=padding)

The implementation does not check that the initialization of Pool3dParameters completes successfully:

Pool3dParameters params{context,  ksize_,       stride_,
                        padding_, data_format_, tensor_in.shape()};

Since the constructor uses OP_REQUIRES to validate conditions, the first assertion that fails interrupts the initialization of params, making it contain invalid data. In turn, this might cause a heap buffer overflow, depending on default initialized values.

Patches

We have patched the issue in GitHub commit 63c6a29d0f2d692b247f7bf81f8732d6442fad09.

The fix will be included in TensorFlow 2.5.0. We will also cherrypick this commit 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.

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