linux - shell 中的错误粘贴导致 CPU 负载变得非常高，然后失控

Question

今天我错误地将一个字符串粘贴到我的 linux shell 中，之后 CPU 负载变得非常高，然后就失去了控制

我的环境是CentOS 6.5，我粘贴的字符串是json格式的请求日志:

[{"timestamp":1487240104178,"info":{"method":"GET","path":"/APIService/v1/refreshSession","headers":{"request":{"user-agent":"curl/7.19.7 (x86_64-redhat-linux-gnu) libcurl/7.19.7 NSS/3.19.1 Basic ECC zlib/1.2.3 libidn/1.18 libssh2/1.4.2","host":"172.22.3.12:8122","accept":"*/*"},"response":{"X-Application-Context":"application:8122","status":"404"}}}},{"timestamp":1487240077403,"info":{"method":"GET","path":"/APIService/v1/refreshSession","headers":{"request":{"user-agent":"curl/7.19.7 (x86_64-redhat-linux-gnu) libcurl/7.19.7 NSS/3.19.1 Basic ECC zlib/1.2.3 libidn/1.18 libssh2/1.4.2","host":"172.22.3.12:8122","accept":"*/*"},"response":{"X-Application-Context":"application:8122","status":"404"}}}},{"timestamp":1487240075185,"info":{"method":"GET","path":"/APIService/v1/refreshSession","headers":{"request":{"user-agent":"curl/7.19.7 (x86_64-redhat-linux-gnu) libcurl/7.19.7 NSS/3.19.1 Basic ECC zlib/1.2.3 libidn/1.18 libssh2/1.4.2","host":"172.22.3.12:8122","accept":"*/*"},"response":{"X-Application-Context":"application:8122","status":"404"}}}},{"timestamp":1487240050994,"info":{"method":"GET","path":"/APIService/v1/refreshSession","headers":{"request":{"user-agent":"curl/7.19.7 (x86_64-redhat-linux-gnu) libcurl/7.19.7 NSS/3.19.1 Basic ECC zlib/1.2.3 libidn/1.18 libssh2/1.4.2","host":"172.22.3.12:8122","accept":"*/*"},"response":{"X-Application-Context":"application:8122","status":"404"}}}},{"timestamp":1487240037110,"info":{"method":"GET","path":"/APIService/v1/refreshSession","headers":{"request":{"user-agent":"curl/7.19.7 (x86_64-redhat-linux-gnu) libcurl/7.19.7 NSS/3.19.1 Basic ECC zlib/1.2.3 libidn/1.18 libssh2/1.4.2","host":"172.22.3.12:8122","accept":"*/*"},"response":{"X-Application-Context":"application:8122","status":"404"}}}},{"timestamp":1487240025956,"info":{"method":"GET","path":"/APIService/v1/refreshSession","headers":{"request":{"user-agent":"curl/7.19.7 (x86_64-redhat-linux-gnu) libcurl/7.19.7 NSS/3.19.1 Basic ECC zlib/1.2.3 libidn/1.18 libssh2/1.4.2","host":"172.22.3.12:8122","accept":"*/*"},"response":{"X-Application-Context":"application:8122","status":"404"}}}},{"timestamp":1487239999461,"info":{"method":"GET","path":"/APIService/v1/refreshSession","headers":{"request":{"host":"172.22.1.15","remote_addr":"172.22.1.15","x-real-ip":"172.22.1.15","x-forwarded-for":"172.22.1.15","user-agent":"curl/7.19.7 (x86_64-redhat-linux-gnu) libcurl/7.19.7 NSS/3.19.1 Basic ECC zlib/1.2.3 libidn/1.18 libssh2/1.4.2","accept":"*/*"},"response":{"X-Application-Context":"application:8122","status":"404"}}}},{"timestamp":1487239998662,"info":{"method":"GET","path":"/APIService/v1/refreshSession","headers":{"request":{"host":"172.22.1.15","remote_addr":"172.22.1.15","x-real-ip":"172.22.1.15","x-forwarded-for":"172.22.1.15","user-agent":"curl/7.19.7 (x86_64-redhat-linux-gnu) libcurl/7.19.7 NSS/3.19.1 Basic ECC zlib/1.2.3 libidn/1.18 libssh2/1.4.2","accept":"*/*"},"response":{"X-Application-Context":"application:8122","status":"404"}}}},{"timestamp":1487239889129,"info":{"method":"GET","path":"/APIservice/v1/refreshSession","headers":{"request":{"host":"172.22.1.15","remote_addr":"172.22.1.15","x-real-ip":"172.22.1.15","x-forwarded-for":"172.22.1.15","user-agent":"curl/7.19.7 (x86_64-redhat-linux-gnu) libcurl/7.19.7 NSS/3.19.1 Basic ECC zlib/1.2.3 libidn/1.18 libssh2/1.4.2","accept":"*/*"},"response":{"X-Application-Context":"application:8122","status":"404"}}}}][root@web-01 conf]

重启后机器一切正常。

谁能告诉我发生了什么事，为什么该字符串导致如此高的 CPU 负载？

Answer 1

关于字符串末尾的[root@web-01 conf]。这是 shell 提示吗？您是否以 root 身份登录到 shell？我打你手腕!不要这样做。

我不确定，但我相信 shell 正在尝试将字符串扩展为命令，但由于字符串 */* 多次出现而碰壁。当 bash 看到 {a,b,c,*/*} 形式的字符串时，它会尝试将其扩展为字符串 a b c ...，其中 ... 是 glob */* 的扩展。当它看到嵌套的括号扩展时，它也会扩展它们。我认为你已经发生了组合爆炸。