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使用压缩时，openssh 会挂起，cpu 使用率达到 100%

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使用压缩时，openssh 会挂起，cpu 使用率达到 100%

当请求压缩时，ansible openssh 服务器会挂起，cpu 占用 100% ( ssh -C)

ssh -vvv -C root@host
[...]
debug3: send packet: type 50
debug3: receive packet: type 52
debug1: Enabling compression at level 6.
debug1: Authentication succeeded (publickey).
Authenticated to host
debug1: channel 0: new [client-session]
debug3: ssh_session2_open: channel_new: 0
debug2: channel 0: send open
debug3: send packet: type 90
debug1: Requesting [email protected]
debug3: send packet: type 80
debug1: Entering interactive session.
debug1: pledge: proc

然后客户端挂起（不再对 ctrl-c 做出反应）并且服务器有一个 CPU 占用率为 100％ 的进程（但接受新的 ssh 连接）。

客户端上的 strace 结束于：

ioctl(0, TCGETS, {B38400 opost isig icanon echo ...}) = 0
ioctl(0, TCGETS, {B38400 opost isig icanon echo ...}) = 0
ioctl(0, SNDCTL_TMR_STOP or TCSETSW, {B38400 -opost -isig -icanon -echo ...}) = 0
                                                                                 ioctl(0, TCGETS, {B38400 -opost -isig -icanon -echo ...}) = 0
                                                                                                                                              clock_gettime(CLOCK_BOOTTIME, {tv_sec=337152, tv_nsec=214378998}) = 0
                                                      clock_gettime(CLOCK_BOOTTIME, {tv_sec=337152, tv_nsec=214391217}) = 0
                                                                                                                           select(9, [5], [4], NULL, {tv_sec=300, tv_usec=0}) = 1 (out [4], left {tv_sec=299, tv_usec=999998})
                                                                 clock_gettime(CLOCK_BOOTTIME, {tv_sec=337152, tv_nsec=214421550}) = 0
                                                                                                                                      write(4, "\302rv\230\347\310G\357T\204\272\3\27\1\341aE\20\317\233\374>\234\217&\0#g\241\225U\215"..., 112) = 112
                                                                                          clock_gettime(CLOCK_BOOTTIME, {tv_sec=337152, tv_nsec=214447208}) = 0
  clock_gettime(CLOCK_BOOTTIME, {tv_sec=337152, tv_nsec=214457769}) = 0
                                                                       select(9, [5], [], NULL, {tv_sec=300, tv_usec=0}

在服务器上进行 Strace：一旦进程挂起，连接到strace -p挂起的进程将不再显示任何内容。连接到主进程时，连接时会显示：

Process 257 attached
select(7, [3 4], NULL, NULL, NULL)      = 1 (in [3])
accept(3, {sa_family=AF_INET, sin_port=htons(43604), sin_addr=inet_addr("192.168.100.1")}, [16]) = 5
fcntl(5, F_GETFL)                       = 0x2 (flags O_RDWR)
pipe([6, 7])                            = 0
socketpair(PF_LOCAL, SOCK_STREAM, 0, [8, 9]) = 0
rt_sigprocmask(SIG_BLOCK, ~[], [], 8)   = 0
fork()                                  = 821
rt_sigprocmask(SIG_SETMASK, [], NULL, 8) = 0
close(7)                                = 0
write(8, "\0\0\0\366\0", 5)             = 5
write(8, "\0\0\0\355\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n"..., 245) = 245
close(8)                                = 0
close(9)                                = 0
close(5)                                = 0
getpid()                                = 257
getpid()                                = 257
getpid()                                = 257
select(7, [3 4 6], NULL, NULL, NULL)    = 1 (in [6])
close(6)                                = 0
select(7, [3 4], NULL, NULL, NULL

此后，直到下一个（挂起的）连接才会再产生相同的输出。

答案1

似乎是一个已知错误Alpine Linux 中的 openssh。

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