CWE

Common Weakness Enumeration

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ID

CWE-1341: Multiple Releases of Same Resource or Handle

Weakness ID: 1341
Abstraction: Base
Structure: Simple
Status: Incomplete
Presentation Filter:
+ Description
The product attempts to close or release a resource or handle more than once, without an intervening successful open.
+ Extended Description

Code typically requires "opening" handles or references to resources such as memory, files, devices, connections, services, etc. When the code is finished with using the resource, it is typically expected to "close" or "release" the resource, which indicates to the environment (such as the OS) that the resource can be re-assigned or reused by unrelated processes or actors. APIs or other abstractions are often used to perform this release, such as free() or delete() within C/C++, or file-handle close() operations that are used in many languages.

Unfortunately, the implementation or design of such APIs might expect the developer to be responsible for ensuring that such APIs are only called once per release of the resource. if the developer attempts to release the same resource/handle more than onc, then the API's expectations are not met, resulting in undefined and/or insecure behavior. This could lead to consequences such as memory corruption, data corruption, execution path corruption, or other consequences.

Note that while the implementation for most (if not all) resource reservation allocations involve a unique identifier/pointer/symbolic reference, then if this identifier is reused, checking the identifier for resource closure may result in a false state of openness and closing of the wrong resource. For this reason, reuse of identifiers is discouraged.

+ Relationships
Section HelpThis 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)
NatureTypeIDName
ChildOfClassClass - 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.675Multiple Operations on Resource in Single-Operation Context
ParentOfVariantVariant - 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.415Double Free
CanPrecedeClassClass - 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.672Operation on a Resource after Expiration 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.
PhaseNote
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

Java (Undetermined Prevalence)

Rust (Undetermined Prevalence)

Class: Language-Independent (Undetermined Prevalence)

C (Undetermined Prevalence)

C++ (Undetermined Prevalence)

Operating Systems

Class: OS-Independent (Undetermined Prevalence)

Architectures

Class: Architecture-Independent (Undetermined Prevalence)

Technologies

Class: Technology-Independent (Undetermined Prevalence)

+ 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.
ScopeImpactLikelihood
Availability
Integrity

Technical Impact: DoS: Crash, Exit, or Restart

Medium
+ Demonstrative Examples

Example 1

This example attempts to close the file twice. In some cases, the C library fclose() function will catch the error and return an error code. In other implementations, a double-free (CWE-415) occurs causing the program to fault. Note that the examples presented here are simplistic, and double fclose() calls will frequently be spread around a program, making them more difficult to find during code reviews.

(bad code)
Example Language:
char b[2000];
FILE *f = fopen("dbl_cls.c", "r");
if (f)
{
b[0] = 0;
fread(b, 1, sizeof(b) - 1, f);
printf("%s\n'", b);
int r1 = fclose(f);
printf("\n-----------------\n1 close done '%d'\n", r1);

int r2 = fclose(f); // Double close
printf("2 close done '%d'\n", r2);
}

This example only has one call to fclose(). While this is certainly the preferred handling of this problem, this simplistic method is not always possible.

(good code)
Example Language:
char b[2000];
FILE *f = fopen("dbl_cls.c", "r");
if (f)
{
b[0] = 0;
fread(b, 1, sizeof(b) - 1, f);
printf("%s\n'", b);
int r1 = fclose(f);
printf("\n-----------------\n1 close done '%d'\n", r1);

}

This example uses a flag to call fclose() only once. Note that this flag is explicit. The variable "f" could also have been used as it will be either NULL if the file is not able to be opened or a valid pointer if the file was successfully opened. If "f" is replacing "f_flg" then "f" would need to be set to NULL after the first fclose() call so the second fclose call would never be executed.

(good code)
Example Language:
char b[2000];
int f_flg = 0;
FILE *f = fopen("dbl_cls.c", "r");
if (f)
{
f_flg = 1;
b[0] = 0;
fread(b, 1, sizeof(b) - 1, f);
printf("%s\n'", b);
if (f_flg)
{
int r1 = fclose(f);
f_flg = 0;
printf("\n-----------------\n1 close done '%d'\n", r1);

}

if (f_flg)
{
int r2 = fclose(f); // Double close
f_flg = 0;
printf("2 close done '%d'\n", r2);

}

}
+ Observed Examples
ReferenceDescription
file descriptor double close can cause the wrong file to be associated with a file descriptor.
Chain: Signal handler contains too much functionality (CWE-828), introducing a race condition that leads to a double free (CWE-415).
Double free resultant from certain error conditions.
+ Potential Mitigations

Phase: Implementation

When closing a resource, set the associated variable to NULL or equivalent value for the given language. Some APIs will ignore this null value or lead to application crashes or exceptions, which may be preferable to data/memory corruption.

Phase: Implementation

Implementing a flag that is set when the resource is opened and cleared when it is closed and checked before closing can be effective at prevention.
+ Detection Methods

Automated Static Analysis

For commonly-used APIs and resource types, automated tools often have signatures that can spot this issue.

Automated Dynamic Analysis

Some compiler instrumentation tools such as AddressSanitizer (ASan) can indirectly detect some instances of this weakness.
+ Notes

Terminology

The terms related to "release" may vary depending on the type of resource, programming language, specification, or framework. "Close" has been used synonymously for the release of resources like file descriptors and file handles. "Return" is sometimes used instead of Release. "Free" is typically used when releasing memory or buffers back into the system for reuse.
+ References
[REF-1198] "close - Perldoc Browser". <https://perldoc.perl.org/functions/close>.
[REF-1199] "io — Core tools for working with streams — Python 3.9.7 documentation". 2021-09-02. <https://docs.python.org/3.9/library/io.html#io.IOBase.close>.
[REF-1200] "FileOutputStream (Java Platform SE 7 )". 2020. <https://docs.oracle.com/javase/7/docs/api/java/io/FileOutputStream.html>.
[REF-1201] "FileOutputStream (Java SE 11 & JDK 11 )". 2021. <https://docs.oracle.com/en/java/javase/11/docs/api/java.base/java/io/FileOutputStream.html>.
+ Content History
+ Submissions
Submission DateSubmitterOrganization
2021-09-07CWE Content TeamMITRE
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Page Last Updated: October 26, 2021