在使用OpenSSL的RSA加解密的时候,发现RSA_new()初始化和RSA_free()释放RSA结构体后依然会有内存泄漏。网上Baidu、Google之,发现这个相关信息很少(至少中文搜索结果是这样,不知是研究这个的人太少还是这个太基础了。。。),最后终于在某个E文论坛上找到了解决办法。在这里总结了一下,供大家参考。我的OpenSSL版本是0.9.8l。(by 月落上弦)
具体如下:
RSA * rsa = RSA_new();
RSA_free( rsa );
产生内存泄漏:
![](https://images.cnblogs.com/OutliningIndicators/ContractedBlock.gif)
Detected memory leaks!
Dumping objects ->
{140} normal block at 0x003B97A0, 12 bytes long.
Data: < ; > B8 96 3B 00 00 00 00 00 06 00 00 00
{139} normal block at 0x003B9750, 16 bytes long.
Data: < > 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
{138} normal block at 0x003B9700, 20 bytes long.
Data: < P ; > 00 00 00 00 50 97 3B 00 00 00 00 00 04 00 00 00
{137} normal block at 0x003B96B8, 12 bytes long.
Data: < ; > 06 00 00 00 00 97 3B 00 00 00 00 00
{136} normal block at 0x003B9638, 64 bytes long.
Data: < > 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
{135} normal block at 0x003B9598, 96 bytes long.
Data: <8 ; A A > 38 96 3B 00 C0 FD 41 00 B0 FD 41 00 08 00 00 00
Object dump complete.
Dumping objects ->
{140} normal block at 0x003B97A0, 12 bytes long.
Data: < ; > B8 96 3B 00 00 00 00 00 06 00 00 00
{139} normal block at 0x003B9750, 16 bytes long.
Data: < > 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
{138} normal block at 0x003B9700, 20 bytes long.
Data: < P ; > 00 00 00 00 50 97 3B 00 00 00 00 00 04 00 00 00
{137} normal block at 0x003B96B8, 12 bytes long.
Data: < ; > 06 00 00 00 00 97 3B 00 00 00 00 00
{136} normal block at 0x003B9638, 64 bytes long.
Data: < > 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
{135} normal block at 0x003B9598, 96 bytes long.
Data: <8 ; A A > 38 96 3B 00 C0 FD 41 00 B0 FD 41 00 08 00 00 00
Object dump complete.
解决方法很简单:
调用OpenSSL的crypto库,在退出前需要调用API "CRYPTO_cleanup_all_ex_data",清除管理CRYPTO_EX_DATA的全局hash表中的数据,避免内存泄漏。如下:
RSA * rsa = RSA_new();
RSA_free( rsa );
CRYPTO_cleanup_all_ex_data();
这样就没有内存泄漏了。
需要注意的是,CRYPTO_cleanup_all_ex_data()不能在potential race-conditions条件在调用(不太懂这个术语,我理解的意思是当函数外部存在RSA结构体的时候,在函数内部执行CRYPTO_cleanup_all_ex_data()将导致函数外的RSA结构体也被清理掉),因此最好在程序结束的时候才调用。
关于CRYPTO_cleanup_all_ex_data()的注释说明和代码如下:
/* Release all "ex_data" state to prevent memory leaks. This can't be made
* thread-safe without overhauling a lot of stuff, and shouldn't really be
* called under potential race-conditions anyway (it's for program shutdown
* after all). */
void CRYPTO_cleanup_all_ex_data(void)
{
IMPL_CHECK
EX_IMPL(cleanup)();
}
* thread-safe without overhauling a lot of stuff, and shouldn't really be
* called under potential race-conditions anyway (it's for program shutdown
* after all). */
void CRYPTO_cleanup_all_ex_data(void)
{
IMPL_CHECK
EX_IMPL(cleanup)();
}
同样,其他相应的模块也需要在使用后清理:
CONF_modules_unload(1); //for conf
EVP_cleanup(); //For EVP
ENGINE_cleanup(); //for engine
CRYPTO_cleanup_all_ex_data(); //generic
ERR_remove_state(0); //for ERR
ERR_free_strings(); //for ERR
EVP_cleanup(); //For EVP
ENGINE_cleanup(); //for engine
CRYPTO_cleanup_all_ex_data(); //generic
ERR_remove_state(0); //for ERR
ERR_free_strings(); //for ERR
http://www.cnblogs.com/moonset7/archive/2009/12/30/1635770.html 月落上弦