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Null pointer dereference and heap OOB read in operations restoring tensors

High severity GitHub Reviewed Published Aug 11, 2021 in tensorflow/tensorflow • Updated Feb 1, 2023

Package

pip tensorflow (pip)

Affected versions

< 2.3.4
>= 2.4.0, < 2.4.3
= 2.5.0

Patched versions

2.3.4
2.4.3
2.5.1
pip tensorflow-cpu (pip)
< 2.3.4
>= 2.4.0, < 2.4.3
= 2.5.0
2.3.4
2.4.3
2.5.1
pip tensorflow-gpu (pip)
< 2.3.4
>= 2.4.0, < 2.4.3
= 2.5.0
2.3.4
2.4.3
2.5.1

Description

Impact

When restoring tensors via raw APIs, if the tensor name is not provided, TensorFlow can be tricked into dereferencing a null pointer:

import tensorflow as tf

tf.raw_ops.Restore(
  file_pattern=['/tmp'],
  tensor_name=[], 
  default_value=21,
  dt=tf.int,
  preferred_shard=1)

The same undefined behavior can be triggered by tf.raw_ops.RestoreSlice:

import tensorflow as tf

tf.raw_ops.RestoreSlice(
  file_pattern=['/tmp'],
  tensor_name=[], 
  shape_and_slice='2',
  dt=inp.array([tf.int]),
  preferred_shard=1)

Alternatively, attackers can read memory outside the bounds of heap allocated data by providing some tensor names but not enough for a successful restoration:

import tensorflow as tf

tf.raw_ops.Restore(
  file_pattern=['/tmp'],
  tensor_name=['x'], 
  default_value=21,
  dt=tf.int,
  preferred_shard=42)

The implementation retrieves the tensor list corresponding to the tensor_name user controlled input and immediately retrieves the tensor at the restoration index (controlled via preferred_shard argument). This occurs without validating that the provided list has enough values.

If the list is empty this results in dereferencing a null pointer (undefined behavior). If, however, the list has some elements, if the restoration index is outside the bounds this results in heap OOB read.

Patches

We have patched the issue in GitHub commit 9e82dce6e6bd1f36a57e08fa85af213e2b2f2622.

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.

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 members of the Aivul Team from Qihoo 360.

References

@mihaimaruseac mihaimaruseac published to tensorflow/tensorflow Aug 11, 2021
Published by the National Vulnerability Database Aug 12, 2021
Reviewed Aug 23, 2021
Published to the GitHub Advisory Database Aug 25, 2021
Last updated Feb 1, 2023

Severity

High

CVSS overall score

This score calculates overall vulnerability severity from 0 to 10 and is based on the Common Vulnerability Scoring System (CVSS).
/ 10

CVSS v3 base metrics

Attack vector
Local
Attack complexity
Low
Privileges required
None
User interaction
None
Scope
Unchanged
Confidentiality
High
Integrity
High
Availability
High

CVSS v3 base metrics

Attack vector: More severe the more the remote (logically and physically) an attacker can be in order to exploit the vulnerability.
Attack complexity: More severe for the least complex attacks.
Privileges required: More severe if no privileges are required.
User interaction: More severe when no user interaction is required.
Scope: More severe when a scope change occurs, e.g. one vulnerable component impacts resources in components beyond its security scope.
Confidentiality: More severe when loss of data confidentiality is highest, measuring the level of data access available to an unauthorized user.
Integrity: More severe when loss of data integrity is the highest, measuring the consequence of data modification possible by an unauthorized user.
Availability: More severe when the loss of impacted component availability is highest.
CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

EPSS score

0.044%
(14th percentile)

CVE ID

CVE-2021-37639

GHSA ID

GHSA-gh6x-4whr-2qv4

Source code

No known source code
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