COMMON WEAKNESS ENUMERATIONDraft

CWE-609

Double-Checked Locking

The product uses double-checked locking to access a resource without the overhead of explicit synchronization, but the locking is insufficient.

Soyutlama

Base

Yapı

Simple

Sömürü İhtimali

Medium

Problemi anla

Problem nedir?

The product uses double-checked locking to access a resource without the overhead of explicit synchronization, but the locking is insufficient.

Genişletilmiş açıklama

Double-checked locking refers to the situation where a programmer checks to see if a resource has been initialized, grabs a lock, checks again to see if the resource has been initialized, and then performs the initialization if it has not occurred yet. This should not be done, as it is not guaranteed to work in all languages and on all architectures. In summary, other threads may not be operating inside the synchronous block and are not guaranteed to see the operations execute in the same order as they would appear inside the synchronous block.

Kök neden

Problem nasıl ve ne zaman oluşur?

Yaşam döngüsü evresi

Implementation

Risk

Başarılı sömürü neye yol açar?

Modify Application DataAlter Execution Logic

Etkilenen güvenlik alanları: Integrity, Other

Savunma

Nasıl önlenir ve çözülür?

Implementation

Uygulama aşaması savunması

Detay
While double-checked locking can be achieved in some languages, it is inherently flawed in Java before 1.5, and cannot be achieved without compromising platform independence. Before Java 1.5, only use of the synchronized keyword is known to work. Beginning in Java 1.5, use of the "volatile" keyword allows double-checked locking to work successfully, although there is some debate as to whether it achieves sufficient performance gains. See references.

Doğrulama

Nasıl tespit edilir?

Automated Static Analysis

Automated static analysis, commonly referred to as Static Application Security Testing (SAST), can find some instances of this weakness by analyzing source code (or binary/compiled code) without having to execute it. Typically, this is done by building a model of data flow and control flow, then searching for potentially-vulnerable patterns that connect "sources" (origins of input) with "sinks" (destinations where the data interacts with external components, a lower layer such as the OS, etc.)