未释放内存泄漏 class_copyPropertyList

Question

因此，分析我的应用程序时存在一些漏洞。一个是 objc_property_t *properties = class_copyPropertyList(self.class, NULL); 没有被释放。

但是当我添加 free(properties)

alloc: *** error for object 0x10b773f58: pointer being freed was not allocated *** set a breakpoint in malloc_error_break to debug

代码看起来像这样：

- (void) encodeWithCoder:(NSCoder *)aCoder {

    objc_property_t *properties = class_copyPropertyList(self.class, NULL);

    while (*properties != '[=11=]') {

        NSString *pname = [NSString stringWithUTF8String:property_getName(*properties)];
        const char * attrs = property_getAttributes(*properties);

        // do something here and set the value to be encoded

        }
        properties ++;
    }
    free(properties);
}

An array of pointers of type objc_property_t describing the properties declared by the class. Any properties declared by superclasses are not included. The array contains *outCount pointers followed by a NULL terminator. You must free the array with free().

代码有效，但有漏洞。现在当我添加 free(properties) 它崩溃了。

Answer 1

您正在递增循环中的 properties 指针，因此在您调用 free(properties) 时它不再引用相同的内存地址。因此 pointer being freed was not allocated 消息。

您需要以非破坏性方式迭代属性，或者在循环之前将原始指针值复制到另一个指针变量。

类似

unsigned int count;
objc_property_t *properties = class_copyPropertyList([self class], &count);
for (unsigned int i = 0; i < count; i++) {
    objc_property_t property = properties[i];
    // ... 
}
free(properties);

或

objc_property_t *properties = class_copyPropertyList([self class], NULL);
objc_property_t *iterationPointer = properties;
while (*iterationPointer != NULL) {
    // ...
    iterationPointer++;
}
free(properties);

未释放内存泄漏 class_copyPropertyList

memory leak on not freed class_copyPropertyList

objective-c

memory-leaks

runtime