CWE-469: Use of Pointer Subtraction to Determine Size
CWE版本: 4.18
更新日期: 2025-09-09
弱点描述
The product subtracts one pointer from another in order to determine size, but this calculation can be incorrect if the pointers do not exist in the same memory chunk.
常见后果
影响范围: Access Control Integrity Confidentiality Availability
技术影响: Modify Memory Read Memory Execute Unauthorized Code or Commands Gain Privileges or Assume Identity
说明: There is the potential for arbitrary code execution with privileges of the vulnerable program.
潜在缓解措施
阶段: Implementation
描述: Save an index variable. This is the recommended solution. Rather than subtract pointers from one another, use an index variable of the same size as the pointers in question. Use this variable to "walk" from one pointer to the other and calculate the difference. Always validate this number.
检测方法
方法: Fuzzing
Fuzz testing (fuzzing) is a powerful technique for generating large numbers of diverse inputs - either randomly or algorithmically - and dynamically invoking the code with those inputs. Even with random inputs, it is often capable of generating unexpected results such as crashes, memory corruption, or resource consumption. Fuzzing effectively produces repeatable test cases that clearly indicate bugs, which helps developers to diagnose the issues.
有效性: High
方法: 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.)
有效性: High
引入模式
| 阶段 | 说明 |
|---|---|
| Implementation | - |
适用平台
编程语言
分类映射
| 分类名称 | 条目ID | 条目名称 | 映射适配度 |
|---|---|---|---|
| CLASP | - | Improper pointer subtraction | - |
| CERT C Secure Coding | ARR36-C | Do not subtract or compare two pointers that do not refer to the same array | Exact |
| Software Fault Patterns | SFP7 | Faulty Pointer Use | - |