CWE-415 双重释放

Double Free

结构: Simple

Abstraction: Variant

状态: Draft

被利用可能性: High

基本描述

The product calls free() twice on the same memory address, potentially leading to modification of unexpected memory locations.

扩展描述

When a program calls free() twice with the same argument, the program's memory management data structures become corrupted. This corruption can cause the program to crash or, in some circumstances, cause two later calls to malloc() to return the same pointer. If malloc() returns the same value twice and the program later gives the attacker control over the data that is written into this doubly-allocated memory, the program becomes vulnerable to a buffer overflow attack.

相关缺陷

• cwe_Nature: ChildOf cwe_CWE_ID: 825 cwe_View_ID: 1000 cwe_Ordinal: Primary

• cwe_Nature: ChildOf cwe_CWE_ID: 672 cwe_View_ID: 1003 cwe_Ordinal: Primary

• cwe_Nature: ChildOf cwe_CWE_ID: 666 cwe_View_ID: 1000

• cwe_Nature: ChildOf cwe_CWE_ID: 675 cwe_View_ID: 1000

• cwe_Nature: PeerOf cwe_CWE_ID: 416 cwe_View_ID: 1000

• cwe_Nature: PeerOf cwe_CWE_ID: 416 cwe_View_ID: 699

• cwe_Nature: PeerOf cwe_CWE_ID: 123 cwe_View_ID: 1000

适用平台

Language: [{'cwe_Name': 'C', 'cwe_Prevalence': 'Undetermined'}, {'cwe_Name': 'C++', 'cwe_Prevalence': 'Undetermined'}]

常见的影响

可能的缓解方案

Architecture and Design

策略:

Choose a language that provides automatic memory management.

Implementation

策略:

Ensure that each allocation is freed only once. After freeing a chunk, set the pointer to NULL to ensure the pointer cannot be freed again. In complicated error conditions, be sure that clean-up routines respect the state of allocation properly. If the language is object oriented, ensure that object destructors delete each chunk of memory only once.

Implementation

策略:

Use a static analysis tool to find double free instances.

示例代码

例

The following code shows a simple example of a double free vulnerability.

bad C

Double free vulnerabilities have two common (and sometimes overlapping) causes:

None

Although some double free vulnerabilities are not much more complicated than the previous example, most are spread out across hundreds of lines of code or even different files. Programmers seem particularly susceptible to freeing global variables more than once.

例

While contrived, this code should be exploitable on Linux distributions which do not ship with heap-chunk check summing turned on.

bad C

分析过的案例

Notes

Relationship
This is usually resultant from another weakness, such as an unhandled error or race condition between threads. It could also be primary to weaknesses such as buffer overflows.
Maintenance
It could be argued that Double Free would be most appropriately located as a child of "Use after Free", but "Use" and "Release" are considered to be distinct operations within vulnerability theory, therefore this is more accurately "Release of a Resource after Expiration or Release", which doesn't exist yet.

分类映射

引用

• REF-44 24 Deadly Sins of Software Security

• REF-62 The Art of Software Security Assessment

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