fix segfault using proxy_ssl_asynch and keepalive

[poincent]

If the async event handler is ngx_ssl_handshake_async_handler and the timer expires while the connection is in keepalive saving state, the connection->log will cause segfault bacause it was changed to ngx_cycle->log.

The async timer is removed in the keepalive free handler to fix the problem and set the async event log

Backtrace of coredump is following:

0  0x00007fd78981a583 in ngx_http_upstream_ssl_handshake_handler (c=0x7fd789b25d68)
    at src/http/ngx_http_upstream.c:1743
1  0x00007fd7897df5ff in ngx_event_expire_timers () at src/event/ngx_event_timer.c:94
2  0x00007fd7897df1bd in ngx_process_events_and_timers (cycle=0x7fd789b036b0) at src/event/ngx_event.c:261
3  0x00007fd7897e82c8 in ngx_worker_process_cycle (cycle=0x7fd789b036b0, data=<value optimized out>)
    at src/os/unix/ngx_process_cycle.c:767
4  0x00007fd7897e6573 in ngx_spawn_process (cycle=0x7fd789b036b0, proc=0x7fd7897e8250 <ngx_worker_process_cycle>,
    data=0x0, name=0x7fd78987d2cb "worker process", respawn=-3) at src/os/unix/ngx_process.c:199
5  0x00007fd7897e7a40 in ngx_start_worker_processes (cycle=0x7fd789b036b0, n=1, type=-3)
    at src/os/unix/ngx_process_cycle.c:361
6  0x00007fd7897e8ee1 in ngx_master_process_cycle (cycle=0x7fd789b036b0) at src/os/unix/ngx_process_cycle.c:133
7  0x00007fd7897bdafe in main (argc=<value optimized out>, argv=<value optimized out>) at src/core/nginx.c:389

nginx -V

nginx version: nginx/1.14.2
built by gcc 4.5.2 (Ubuntu/Linaro 4.5.2-8ubuntu4) 
built with OpenSSL 1.1.0h  27 Mar 2018
TLS SNI support enabled
configure arguments: --prefix=/opt/asynch --with-http_ssl_module --with-http_stub_status_module --with-http_v2_module --with-stream --with-stream_ssl_module --with-debug --add-dynamic-module=modules/nginx_qat_module --with-cc-opt='-DNGX_SECURE_MEM -I/opt/qat/QAT1.7/.openssl/include -Wno-error=deprecated-declarations -fno-pie' --with-ld-opt='-Wl,-rpath=/opt/qat/QAT1.7/.openssl/lib -L/opt/qat/QAT1.7/.openssl/lib'

Test configuration

load_module /opt/asynch/modules/ngx_ssl_engine_qat_module.so;
user  root;
worker_processes 1;
worker_cpu_affinity 10;
worker_rlimit_nofile 1048576;
worker_rlimit_core 500M;
working_directory /root;

ssl_engine {
    use_engine qat;
    default_algorithms RSA,EC,DH,PKEY_CRYPTO;
    qat_engine {
        qat_offload_mode async;
        qat_notify_mode poll;
        qat_poll_mode heuristic;
        qat_shutting_down_release on;
    }
}

events {
}

error_log /opt/asynch/logs/error.log error;

http {
    upstream test_server {
      server 33.0.0.100:443 max_fails=0;
      keepalive 2048;
    }

    server {
      error_log /root/debug.log debug;
      proxy_http_version 1.1;
      listen 192.168.215.200:80 default_server backlog=65535;

      location ~ '' {
        proxy_set_header Host $http_host;
        proxy_pass https://test_server;
        proxy_next_upstream off;
        proxy_set_header Connection "";
        proxy_ssl_asynch on;
      }
    }
}

[zhangp8x]

@poincent Sincere apologies for very late reply to this pull request. We intend to merge this pull request which will go through the internal process and should be available in the next release. But before that the commit message in the pull request does not contain "Signed-off-by:" in it adhering to license and Developer Certification of Origin. Could you please update the pull request commit message with "Signed-off-by:" in the following format Signed-off-by: Name

Note: You are required to use your real name in the sign-off message.

[zhangp8x]

@poincent: Thank you for your great help, we are going to include the patch. Since no sign-off-by message is provided, we have to commit it to internal branch without author info.