CWE-690: Unchecked Return Value to NULL Pointer Dereference

Description

The product does not check for an error after calling a function that can return with a NULL pointer if the function fails, which leads to a resultant NULL pointer dereference.

While unchecked return value weaknesses are not limited to returns of NULL pointers (see the examples in CWE-252), functions often return NULL to indicate an error status. When this error condition is not checked, a NULL pointer dereference can occur.

Potential Impact

Demonstrative Examples

String username = getUserName();if (username.equals(ADMIN_USER)) {...}

void host_lookup(char *user_supplied_addr){
                        struct hostent *hp;in_addr_t *addr;char hostname[64];in_addr_t inet_addr(const char *cp);
                           
                           /*routine that ensures user_supplied_addr is in the right format for conversion */
                           
                           validate_addr_form(user_supplied_addr);addr = inet_addr(user_supplied_addr);hp = gethostbyaddr( addr, sizeof(struct in_addr), AF_INET);strcpy(hostname, hp->h_name);
                     }

Detection Methods

• Black Box — This typically occurs in rarely-triggered error conditions, reducing the chances of detection during black box testing.
• White Box — Code analysis can require knowledge of API behaviors for library functions that might return NULL, reducing the chances of detection when unknown libraries are used.
• Automated Dynamic Analysis Moderate — Use tools that are integrated during compilation to insert runtime error-checking mechanisms related to memory safety errors, such as AddressSanitizer (ASan) for C/C++ [REF-1518].

Real-World CVE Examples

Related Weaknesses

Taxonomy Mappings

• CERT C Secure Coding: EXP34-C — Do not dereference null pointers
• The CERT Oracle Secure Coding Standard for Java (2011): ERR08-J — Do not catch NullPointerException or any of its ancestors
• SEI CERT Perl Coding Standard: EXP32-PL — Do not ignore function return values