CWE-835 不可达退出条件的循环（无限循环）

Loop with Unreachable Exit Condition ('Infinite Loop')

结构: Simple

Abstraction: Base

状态: Incomplete

被利用可能性: unkown

基本描述

The program contains an iteration or loop with an exit condition that cannot be reached, i.e., an infinite loop.

扩展描述

If the loop can be influenced by an attacker, this weakness could allow attackers to consume excessive resources such as CPU or memory.

相关缺陷

  • cwe_Nature: ChildOf cwe_CWE_ID: 834 cwe_View_ID: 1000 cwe_Ordinal: Primary

  • cwe_Nature: ChildOf cwe_CWE_ID: 834 cwe_View_ID: 1003 cwe_Ordinal: Primary

  • cwe_Nature: ChildOf cwe_CWE_ID: 834 cwe_View_ID: 699 cwe_Ordinal: Primary

适用平台

Language: {'cwe_Class': 'Language-Independent', 'cwe_Prevalence': 'Undetermined'}

常见的影响

范围 影响 注释
Availability ['DoS: Resource Consumption (CPU)', 'DoS: Resource Consumption (Memory)', 'DoS: Amplification'] An infinite loop will cause unexpected consumption of resources, such as CPU cycles or memory. The software's operation may slow down, or cause a long time to respond.

示例代码

例

In the following code the method processMessagesFromServer attempts to establish a connection to a server and read and process messages from the server. The method uses a do/while loop to continue trying to establish the connection to the server when an attempt fails.

bad C

int processMessagesFromServer(char hostaddr, int port) {
...
int servsock;
int connected;
struct sockaddr_in servaddr;

// create socket to connect to server
servsock = socket( AF_INET, SOCK_STREAM, 0);
memset( &servaddr, 0, sizeof(servaddr));
servaddr.sin_family = AF_INET;
servaddr.sin_port = htons(port);
servaddr.sin_addr.s_addr = inet_addr(hostaddr);

do {

// establish connection to server
connected = connect(servsock, (struct sockaddr )&servaddr, sizeof(servaddr));

// if connected then read and process messages from server
if (connected > -1) {

// read and process messages
...
}

// keep trying to establish connection to the server
} while (connected < 0);

// close socket and return success or failure
...
}

However, this will create an infinite loop if the server does not respond. This infinite loop will consume system resources and can be used to create a denial of service attack. To resolve this a counter should be used to limit the number of attempts to establish a connection to the server, as in the following code.

good C

int processMessagesFromServer(char hostaddr, int port) {
...
// initialize number of attempts counter
int count = 0;
do {

// establish connection to server
connected = connect(servsock, (struct sockaddr )&servaddr, sizeof(servaddr));

// increment counter
count++;

// if connected then read and process messages from server
if (connected > -1) {

// read and process messages
...
}

// keep trying to establish connection to the server

// up to a maximum number of attempts
} while (connected < 0 && count < MAX_ATTEMPTS);

// close socket and return success or failure
...
}

例

For this example the method isReorderNeeded as part of a bookstore application that determines if a particular book needs to be reordered based on the current inventory count and the rate at which the book is being sold.

bad Java

public boolean isReorderNeeded(String bookISBN, int rateSold) {

boolean isReorder = false;

int minimumCount = 10;
int days = 0;

// get inventory count for book
int inventoryCount = inventory.getIventoryCount(bookISBN);

// find number of days until inventory count reaches minimum
while (inventoryCount > minimumCount) {

inventoryCount = inventoryCount - rateSold;
days++;
}

// if number of days within reorder timeframe

// set reorder return boolean to true
if (days > 0 && days < 5) {
isReorder = true;
}

return isReorder;
}

However, the while loop will become an infinite loop if the rateSold input parameter has a value of zero since the inventoryCount will never fall below the minimumCount. In this case the input parameter should be validated to ensure that a value of zero does not cause an infinite loop,as in the following code.

good Java

public boolean isReorderNeeded(String bookISBN, int rateSold) {
...

// validate rateSold variable
if (rateSold < 1) {
return isReorder;
}

...
}

分析过的案例

标识 说明 链接
CVE-2011-1027 Chain: off-by-one error leads to infinite loop using invalid hex-encoded characters. https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2011-1027
CVE-2011-1142 Chain: self-referential values in recursive definitions lead to infinite loop. https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2011-1142
CVE-2011-1002 NULL UDP packet is never cleared from a queue, leading to infinite loop. https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2011-1002
CVE-2010-4476 Floating point conversion routine cycles back and forth between two different values. https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2010-4476
CVE-2010-4645 Floating point conversion routine cycles back and forth between two different values. https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2010-4645
CVE-2010-2534 Chain: improperly clearing a pointer in a linked list leads to infinite loop. https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2010-2534

分类映射

映射的分类名 ImNode ID Fit Mapped Node Name
OMG ASCSM ASCSM-CWE-835

引用