CVE-2021-41213

TensorFlow tf.function deadlock vulnerability due to mutual recursion

• CVSS 5.5
• CWE-662 Improper Synchronization
• Race Conditions
• Remote

TensorFlow is an open source platform for machine learning. In affected versions the code behind `tf.function` API can be made to deadlock when two `tf.function` decorated Python functions are mutually recursive. This occurs due to using a non-reentrant `Lock` Python object. Loading any model which contains mutually recursive functions is vulnerable. An attacker can cause denial of service by causing users to load such models and calling a recursive `tf.function`, although this is not a frequent scenario. The fix will be included in TensorFlow 2.7.0. We will also cherrypick this commit on TensorFlow 2.6.1, TensorFlow 2.5.2, and TensorFlow 2.4.4, as these are also affected and still in supported range.

CVE

CVE-2021-41213

CWE

CWE-662 Improper Synchronization

CVSS base score

5.5

Published

2021-11-05

OWASP

A08 Software and Data Integrity Failures

Orthogonal defect classification

Timing/Serialization

Code defect classification

Serialization Issues

Category

Race Conditions

Subcategory

Race Condition in File Operations

Accessibility scope

Remote

Impact

Denial of Service (DoS)

Affected component

TensorFlow

Fixed by upgrading

Yes

Solution

Update TensorFlow to version 2.7.0 or apply the fix in TensorFlow 2.6.1, TensorFlow 2.5.2, or TensorFlow 2.4.4.

import tensorflow as tf

@tf.function
def func_a():
    return func_b()

@tf.function
def func_b():
    return func_a()

try:
    func_a()
except RuntimeError as e:
    print("Caught a RuntimeError, indicating a potential deadlock:", e)

func_a()

import tensorflow as tf

@tf.function
def func_a(n):
    if n <= 0:
        return tf.constant("Base case from A")
    return func_b(n - 1)

@tf.function
def func_b(n):
    if n <= 0:
        return tf.constant("Base case from B")
    return func_a(n - 1)

try:
    result = func_a(5)
    tf.print(result)
except RuntimeError as e:
    print("Caught a RuntimeError, indicating a potential issue:", e)

@misc{vaitp:cve202141213,
  title        = {{TensorFlow tf.function deadlock vulnerability due to mutual recursion}},
  author       = {Bogaerts, Fr\'ed\'eric and Ivaki, Naghmeh and Fonseca, Jos\'e},
  year         = {2021},
  note         = {VAITP Python Vulnerability Dataset, entry CVE-2021-41213},
  howpublished = {\url{https://netpack.pt/vaitp/vulnerability/CVE-2021-41213/}}
}