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Heap buffer overflow and undefined behavior in `FusedBatchNorm`

Low severity GitHub Reviewed Published May 13, 2021 in tensorflow/tensorflow • Updated Feb 1, 2023

Package

pip tensorflow (pip)

Affected versions

< 2.1.4
>= 2.2.0, < 2.2.3
>= 2.3.0, < 2.3.3
>= 2.4.0, < 2.4.2

Patched versions

2.1.4
2.2.3
2.3.3
2.4.2
pip tensorflow-cpu (pip)
< 2.1.4
>= 2.2.0, < 2.2.3
>= 2.3.0, < 2.3.3
>= 2.4.0, < 2.4.2
2.1.4
2.2.3
2.3.3
2.4.2
pip tensorflow-gpu (pip)
< 2.1.4
>= 2.2.0, < 2.2.3
>= 2.3.0, < 2.3.3
>= 2.4.0, < 2.4.2
2.1.4
2.2.3
2.3.3
2.4.2

Description

Impact

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

import tensorflow as tf

x = tf.zeros([10, 10, 10, 6], dtype=tf.float32)
scale = tf.constant([0.0], shape=[1], dtype=tf.float32)
offset = tf.constant([0.0], shape=[1], dtype=tf.float32)
mean = tf.constant([0.0], shape=[1], dtype=tf.float32)
variance = tf.constant([0.0], shape=[1], dtype=tf.float32)
epsilon = 0.0
exponential_avg_factor = 0.0
data_format = "NHWC"
is_training = False
    
tf.raw_ops.FusedBatchNorm(
  x=x, scale=scale, offset=offset, mean=mean, variance=variance,
  epsilon=epsilon, exponential_avg_factor=exponential_avg_factor,
  data_format=data_format, is_training=is_training)

If the tensors are empty, the same implementation can trigger undefined behavior by dereferencing null pointers:

import tensorflow as tf
import numpy as np

x = tf.zeros([10, 10, 10, 1], dtype=tf.float32)
scale = tf.constant([], shape=[0], dtype=tf.float32)
offset = tf.constant([], shape=[0], dtype=tf.float32)
mean = tf.constant([], shape=[0], dtype=tf.float32)
variance = tf.constant([], shape=[0], dtype=tf.float32)
epsilon = 0.0
exponential_avg_factor = 0.0
data_format = "NHWC"
is_training = False

tf.raw_ops.FusedBatchNorm(
  x=x, scale=scale, offset=offset, mean=mean, variance=variance, 
  epsilon=epsilon, exponential_avg_factor=exponential_avg_factor,
  data_format=data_format, is_training=is_training)

The implementation fails to validate that scale, offset, mean and variance (the last two only when required) all have the same number of elements as the number of channels of x. This results in heap out of bounds reads when the buffers backing these tensors are indexed past their boundary.

If the tensors are empty, the validation mentioned in the above paragraph would also trigger and prevent the undefined behavior.

Patches

We have patched the issue in GitHub commit 6972f9dfe325636b3db4e0bc517ee22a159365c0.

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 Ying Wang and Yakun Zhang of Baidu X-Team.

References

@mihaimaruseac mihaimaruseac published to tensorflow/tensorflow May 13, 2021
Published by the National Vulnerability Database May 14, 2021
Reviewed May 18, 2021
Published to the GitHub Advisory Database May 21, 2021
Last updated Feb 1, 2023

Severity

Low

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
High
Privileges required
Low
User interaction
None
Scope
Unchanged
Confidentiality
None
Integrity
None
Availability
Low

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:H/PR:L/UI:N/S:U/C:N/I:N/A:L

EPSS score

0.048%
(19th percentile)

CVE ID

CVE-2021-29583

GHSA ID

GHSA-9xh4-23q4-v6wr

Source code

No known source code
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