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Home > CWE List > CWE-762: Mismatched Memory Management Routines (4.16)  
ID

CWE-762: Mismatched Memory Management Routines

Weakness ID: 762
Vulnerability Mapping: ALLOWED This CWE ID may be used to map to real-world vulnerabilities
Abstraction: Variant Variant - a weakness that is linked to a certain type of product, typically involving a specific language or technology. More specific than a Base weakness. Variant level weaknesses typically describe issues in terms of 3 to 5 of the following dimensions: behavior, property, technology, language, and resource.
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+ Description
The product attempts to return a memory resource to the system, but it calls a release function that is not compatible with the function that was originally used to allocate that resource.
+ Extended Description

This weakness can be generally described as mismatching memory management routines, such as:

  • The memory was allocated on the stack (automatically), but it was deallocated using the memory management routine free() (CWE-590), which is intended for explicitly allocated heap memory.
  • The memory was allocated explicitly using one set of memory management functions, and deallocated using a different set. For example, memory might be allocated with malloc() in C++ instead of the new operator, and then deallocated with the delete operator.

When the memory management functions are mismatched, the consequences may be as severe as code execution, memory corruption, or program crash. Consequences and ease of exploit will vary depending on the implementation of the routines and the object being managed.

+ Common Consequences
Section HelpThis table specifies different individual consequences associated with the weakness. The Scope identifies the application security area that is violated, while the Impact describes the negative technical impact that arises if an adversary succeeds in exploiting this weakness. The Likelihood provides information about how likely the specific consequence is expected to be seen relative to the other consequences in the list. For example, there may be high likelihood that a weakness will be exploited to achieve a certain impact, but a low likelihood that it will be exploited to achieve a different impact.
Scope Impact Likelihood
Integrity
Availability
Confidentiality

Technical Impact: Modify Memory; DoS: Crash, Exit, or Restart; Execute Unauthorized Code or Commands

+ Potential Mitigations

Phase: Implementation

Only call matching memory management functions. Do not mix and match routines. For example, when you allocate a buffer with malloc(), dispose of the original pointer with free().

Phase: Implementation

Strategy: Libraries or Frameworks

Choose a language or tool that provides automatic memory management, or makes manual memory management less error-prone.

For example, glibc in Linux provides protection against free of invalid pointers.

When using Xcode to target OS X or iOS, enable automatic reference counting (ARC) [REF-391].

To help correctly and consistently manage memory when programming in C++, consider using a smart pointer class such as std::auto_ptr (defined by ISO/IEC ISO/IEC 14882:2003), std::shared_ptr and std::unique_ptr (specified by an upcoming revision of the C++ standard, informally referred to as C++ 1x), or equivalent solutions such as Boost.

Phase: Architecture and Design

Strategy: Libraries or Frameworks

Use a vetted library or framework that does not allow this weakness to occur or provides constructs that make this weakness easier to avoid.

For example, glibc in Linux provides protection against free of invalid pointers.

Phase: Architecture and Design

Use a language that provides abstractions for memory allocation and deallocation.

Phase: Testing

Use a tool that dynamically detects memory management problems, such as valgrind.
+ Relationships
Section Help This table shows the weaknesses and high level categories that are related to this weakness. These relationships are defined as ChildOf, ParentOf, MemberOf and give insight to similar items that may exist at higher and lower levels of abstraction. In addition, relationships such as PeerOf and CanAlsoBe are defined to show similar weaknesses that the user may want to explore.
+ Relevant to the view "Research Concepts" (CWE-1000)
Nature Type ID Name
ChildOf Base Base - a weakness that is still mostly independent of a resource or technology, but with sufficient details to provide specific methods for detection and prevention. Base level weaknesses typically describe issues in terms of 2 or 3 of the following dimensions: behavior, property, technology, language, and resource. 763 Release of Invalid Pointer or Reference
ParentOf Variant Variant - a weakness that is linked to a certain type of product, typically involving a specific language or technology. More specific than a Base weakness. Variant level weaknesses typically describe issues in terms of 3 to 5 of the following dimensions: behavior, property, technology, language, and resource. 590 Free of Memory not on the Heap
Section Help This table shows the weaknesses and high level categories that are related to this weakness. These relationships are defined as ChildOf, ParentOf, MemberOf and give insight to similar items that may exist at higher and lower levels of abstraction. In addition, relationships such as PeerOf and CanAlsoBe are defined to show similar weaknesses that the user may want to explore.
+ Relevant to the view "CISQ Data Protection Measures" (CWE-1340)
Nature Type ID Name
ChildOf Class Class - a weakness that is described in a very abstract fashion, typically independent of any specific language or technology. More specific than a Pillar Weakness, but more general than a Base Weakness. Class level weaknesses typically describe issues in terms of 1 or 2 of the following dimensions: behavior, property, and resource. 404 Improper Resource Shutdown or Release
+ Modes Of Introduction
Section HelpThe different Modes of Introduction provide information about how and when this weakness may be introduced. The Phase identifies a point in the life cycle at which introduction may occur, while the Note provides a typical scenario related to introduction during the given phase.
Phase Note
Implementation
+ Applicable Platforms
Section HelpThis listing shows possible areas for which the given weakness could appear. These may be for specific named Languages, Operating Systems, Architectures, Paradigms, Technologies, or a class of such platforms. The platform is listed along with how frequently the given weakness appears for that instance.

Languages

C (Undetermined Prevalence)

C++ (Undetermined Prevalence)

+ Likelihood Of Exploit
Low
+ Demonstrative Examples

Example 1

This example allocates a BarObj object using the new operator in C++, however, the programmer then deallocates the object using free(), which may lead to unexpected behavior.

(bad code)
Example Language: C++ 
void foo(){
BarObj *ptr = new BarObj()
/* do some work with ptr here */

...

free(ptr);
}

Instead, the programmer should have either created the object with one of the malloc family functions, or else deleted the object with the delete operator.

(good code)
Example Language: C++ 
void foo(){
BarObj *ptr = new BarObj()
/* do some work with ptr here */

...

delete ptr;
}

Example 2

In this example, the program does not use matching functions such as malloc/free, new/delete, and new[]/delete[] to allocate/deallocate the resource.

(bad code)
Example Language: C++ 
class A {
void foo();
};
void A::foo(){
int *ptr;
ptr = (int*)malloc(sizeof(int));
delete ptr;
}

Example 3

In this example, the program calls the delete[] function on non-heap memory.

(bad code)
Example Language: C++ 
class A{
void foo(bool);
};
void A::foo(bool heap) {
int localArray[2] = {
11,22
};
int *p = localArray;
if (heap){
p = new int[2];
}
delete[] p;
}

+ Affected Resources
  • Memory
+ Memberships
Section HelpThis MemberOf Relationships table shows additional CWE Categories and Views that reference this weakness as a member. This information is often useful in understanding where a weakness fits within the context of external information sources.
Nature Type ID Name
MemberOf CategoryCategory - a CWE entry that contains a set of other entries that share a common characteristic. 876 CERT C++ Secure Coding Section 08 - Memory Management (MEM)
MemberOf CategoryCategory - a CWE entry that contains a set of other entries that share a common characteristic. 1172 SEI CERT C Coding Standard - Guidelines 51. Microsoft Windows (WIN)
MemberOf CategoryCategory - a CWE entry that contains a set of other entries that share a common characteristic. 1237 SFP Primary Cluster: Faulty Resource Release
MemberOf CategoryCategory - a CWE entry that contains a set of other entries that share a common characteristic. 1399 Comprehensive Categorization: Memory Safety
+ Vulnerability Mapping Notes

Usage: ALLOWED

(this CWE ID may be used to map to real-world vulnerabilities)

Reason: Acceptable-Use

Rationale:

This CWE entry is at the Variant level of abstraction, which is a preferred level of abstraction for mapping to the root causes of vulnerabilities.

Comments:

Carefully read both the name and description to ensure that this mapping is an appropriate fit. Do not try to 'force' a mapping to a lower-level Base/Variant simply to comply with this preferred level of abstraction.
+ Notes

Applicable Platform

This weakness is possible in any programming language that allows manual management of memory.

+ Taxonomy Mappings
Mapped Taxonomy Name Node ID Fit Mapped Node Name
CERT C Secure Coding WIN30-C Exact Properly pair allocation and deallocation functions
Software Fault Patterns SFP12 Faulty Memory Release
+ References
+ Content History
+ Submissions
Submission Date Submitter Organization
2009-05-08
(CWE 1.4, 2009-05-27)
CWE Content Team MITRE
+ Contributions
Contribution Date Contributor Organization
2010-04-30 Martin Sebor Cisco Systems, Inc.
Provided improvement to existing Mitigation
+ Modifications
Modification Date Modifier Organization
2009-12-28 CWE Content Team MITRE
updated Applicable_Platforms, Likelihood_of_Exploit
2010-06-21 CWE Content Team MITRE
updated Description, Potential_Mitigations
2011-06-01 CWE Content Team MITRE
updated Common_Consequences
2011-09-13 CWE Content Team MITRE
updated Relationships, Taxonomy_Mappings
2012-05-11 CWE Content Team MITRE
updated Demonstrative_Examples, Relationships
2012-10-30 CWE Content Team MITRE
updated Potential_Mitigations
2014-02-18 CWE Content Team MITRE
updated Demonstrative_Examples, Potential_Mitigations, References
2014-07-30 CWE Content Team MITRE
updated Relationships, Taxonomy_Mappings
2017-11-08 CWE Content Team MITRE
updated Applicable_Platforms, References, Taxonomy_Mappings
2019-01-03 CWE Content Team MITRE
updated Relationships
2020-02-24 CWE Content Team MITRE
updated Relationships
2020-12-10 CWE Content Team MITRE
updated Relationships
2021-03-15 CWE Content Team MITRE
updated Relationships
2023-01-31 CWE Content Team MITRE
updated Description
2023-04-27 CWE Content Team MITRE
updated References, Relationships
2023-06-29 CWE Content Team MITRE
updated Mapping_Notes
Page Last Updated: November 19, 2024