SUNRPC: Fix a slow server-side memory leak with RPC-over-TCP

Linux kernel 安全漏洞

SUNRPC：修复RPC-over-TCP中的慢服务器端内存泄漏

In the Linux kernel, the following vulnerability has been resolved: SUNRPC: Fix a slow server-side memory leak with RPC-over-TCP Jan Schunk reports that his small NFS servers suffer from memory exhaustion after just a few days. A bisect shows that commit e18e157bb5c8 ("SUNRPC: Send RPC message on TCP with a single sock_sendmsg() call") is the first bad commit. That commit assumed that sock_sendmsg() releases all the pages in the underlying bio_vec array, but the reality is that it doesn't. svc_xprt_release() releases the rqst's response pages, but the record marker page fragment isn't one of those, so it is never released. This is a narrow fix that can be applied to stable kernels. A more extensive fix is in the works.

Linux kernel是美国Linux基金会的开源操作系统Linux所使用的内核。 Linux kernel 存在安全漏洞，该漏洞源于 SUNRPC 模块存在内存泄露问题。

在Linux内核中，已解决了以下漏洞： SUNRPC：修复TCP上的RPC过慢的服务器端内存泄漏 Jan Schunk报告称，他的小型NFS服务器在几天后就会出现内存耗尽的情况。二进制查找显示，提交e18e157bb5c8（“SUNRPC：使用单个sock_sendmsg（）调用将RPC消息发送到TCP”）是第一个导致问题的提交。 该提交假设sock_sendmsg（）会释放底层bio_vec数组中的所有页面，但实际上并非如此。svc_xprt_release（）会释放rqst的响应页面，但记录标记页面碎片并不包含在内，因此它从未被释放。 这是一个狭窄的修复，可以应用于稳定内核。正在进行更广泛的修复工作。