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.
Submission Date :
April 11, 2008, midnight
Modification Date :
2023-06-29 00:00:00+00:00
Organization :
MITRE
Extended Description
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.
Example - 1
The code below makes a call to the getUserName() function but doesn't check the return value before dereferencing (which may cause a NullPointerException).
...String username = getUserName();if (username.equals(ADMIN_USER)) {}Example - 2
This example takes an IP address from a user, verifies that it is well formed and then looks up the hostname and copies it into a buffer. If an attacker provides an address that appears to be well-formed, but the address does not resolve to a hostname, then the call to gethostbyaddr() will return NULL. Since the code does not check the return value from gethostbyaddr (CWE-252), a NULL pointer dereference (CWE-476) would then occur in the call to strcpy(). Note that this code is also vulnerable to a buffer overflow (CWE-119).
// /*routine that ensures user_supplied_addr is in the right format for conversion *///
struct hostent *hp;in_addr_t *addr;char hostname[64];in_addr_t inet_addr(const char *cp);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);void host_lookup(char *user_supplied_addr){}
Related Weaknesses
This table shows the weaknesses and high level categories that are related to this weakness. These relationships are defined to give an overview of the different insight to similar items that may exist at higher and lower levels of abstraction.
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