SECURITY_STATUS SEC_ENTRY DeleteSecurityContext(PCtxtHandle phContext)
{
	char* Name = NULL;
	SECURITY_STATUS status;
	SecurityFunctionTableA* table;

	Name = (char*) sspi_SecureHandleGetUpperPointer(phContext);

	if (!Name)
		return SEC_E_SECPKG_NOT_FOUND;

	table = sspi_GetSecurityFunctionTableAByNameA(Name);

	if (!table)
		return SEC_E_SECPKG_NOT_FOUND;

	if (table->DeleteSecurityContext == NULL)
		return SEC_E_UNSUPPORTED_FUNCTION;

	status = table->DeleteSecurityContext(phContext);

	return status;
}
A NULL pointer dereference occurs when the application dereferences a pointer that it expects to be valid, but is NULL, typically causing a crash or exit.