Unchecked Return Value to NULL Pointer Dereference

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.

Soyutlama

Compound

Yapı

Chain

Sömürü İhtimali

Medium

Problemi anla

Problem nedir?

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.

Genişletilmiş açıklama

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.

Kök neden

Problem nasıl ve ne zaman oluşur?

Yaşam döngüsü evresi

Implementation

A typical occurrence of this weakness occurs when an application includes user-controlled input to a malloc() call. The related code might be correct with respect to preventing buffer overflows, but if a large value is provided, the malloc() will fail due to insufficient memory. This problem also frequently occurs when a parsing routine expects that certain elements will always be present. If malformed input is provided, the parser might return NULL. For example, strtok() can return NULL.

Risk

Başarılı sömürü neye yol açar?

DoS: Crash, Exit, or Restart

Etkilenen güvenlik alanları: Availability

Execute Unauthorized Code or CommandsRead MemoryModify Memory

Etkilenen güvenlik alanları: Integrity, Confidentiality, Availability

In rare circumstances, when NULL is equivalent to the 0x0 memory address and privileged code can access it, then writing or reading memory is possible, which may lead to code execution.

Savunma

Nasıl önlenir ve çözülür?

Follow secure coding guidelines for input handling and boundary checking.
Enforce strict security reviews and automated static analysis (SAST) checks.

Doğrulama

Nasıl tespit edilir?

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].

Crafted inputs are necessary to reach the code containing the error, such as generated by fuzzers. Also, these tools may reduce performance, and they only report the error condition - not the original mistake that led to the error.