SV.INCORRECT_RESOURCE_HANDLING.URHInsecure resource handling-allocation and releaseResource management issues can lead to over-consumption or exhaustion of resources. When a resource is allocated, it's important to release the resource properly and account for all potential exit paths. Similarly, the code needs to keep track of requests and releases, so that a resource isn't requested after it's been released. This type of defect often occurs in function exits for exceptions or error handling. The SV.INCORRECT_RESOURCE_HANDLING.URH checker flags situations in which a resource is requested after it may have been released. The checker analyzes the following POSIX resources for incorrect resource handling:
For more information, see the latest issue of The Open Group Base Specifications. Vulnerability and riskAlthough this situation is not really a security risk, incorrect error handling can result in software reliability problems, and possibly in exposing sensitive data. If an attacker can intentionally trigger a resource leak, a resource pool could be reduced to the point of denial-of-service (DoS). Mitigation and preventionIt's good practice to ensure that all resources allocated are subsequently freed, and to be consistent with allocation and release of resources in a function and in an application. Error conditions, in particular, should always be checked to make sure that resources are assigned and freed appropriately. Vulnerable code example
1 #include <stdio.h>
2 #include <mqueue.h>
3
4 void message_released(const char* name, const char* data1, const char* data2)
5 {
6
7 char c;
8 mqd_t h;
9 if ((h = mq_open(name, O_RDWR)) != (mqd_t)-1)
10 {
11 mq_receive(h, &c, 1, NULL);
12 if (c == '1')
13 mq_send(h, data1, strlen(data1)+1, 2);
14 else
15
16 if (c == '2')
17 mq_send(h, data2, strlen(data2)+1, 2);
18 mq_close(h);
19 printf("OK.\n");
20 mq_send(h, "OK.", 3, 2); // ERROR
21 }
22 else
23 {
24 fprintf(stderr, "'mq_open' failed for %s\n", name);
25
26 }
27 }
Klocwork produces an issue report at line 20, indicating that handler 'h', which is the result of a call to 'mq_open', was used after it was released in line 18. Incorrect resource handling like this can cause software reliability problems. Fixed code example
1 #include <stdio.h>
2 #include <mqueue.h>
3
4 void message_released(const char* name, const char* data1, const char* data2)
5 {
6
7 char c;
8 mqd_t h;
9 if ((h = mq_open(name, O_RDWR)) != (mqd_t)-1)
10 {
11 mq_receive(h, &c, 1, NULL);
12 if (c == '1')
13 mq_send(h, data1, strlen(data1)+1, 2);
14 else
15
16 if (c == '2')
17 mq_send(h, data2, strlen(data2)+1, 2);
18 printf("OK.\n");
19 mq_send(h, "OK.", 3, 2);
20 mq_close(h);
21 }
22 else
23 {
24 fprintf(stderr, "'mq_open' failed for %s\n", name);
25
26 }
27 }
In the fixed code example, handler 'h' isn't released until line 21, after the call to 'mq_send'. |