openssl 1.1.1w s_client connect block

[linxingyang]

Hello. i'm get trouble when using opnessl.

env：

• arm linux（Cortex-A7） 128M memory
• test with both openssl1.1.1k and openssl1.1.1w

using openssl s_client to test connect like this:

openssl s_client -connect server_ip:server_port -key client.key -cert client.crt -CAfile ca.crt -state  -brief

it's works fine in my arm linux shell. so after that i run 30 processes, every process do that repeatly (Test scenario), c++ code like this :

while (true) {
    // ....download cert from server 
    openssl s_client -connect server_ip:server_port -key client.key -cert client.crt -CAfile ca.crt -state  -brief
    // ....record result
}

but i found some processes were blocked (the timestamp stop update) like this screenshot :

i add some logs to openssl 1.1.1w source code, finally found it block in apps/s_client.c line 2874, the timeoutp is NULL so block forever ( in normal case, it will have read/write incidents few seconds later, but in my test case, it already block more than 10 minutes).

#else
            i = select(width, (void *)&readfds, (void *)&writefds,
                       NULL, timeoutp);
#endif

so, is that a bug ? or just waiting longer select() will return? or i'm misusing openssl s_client connect ?

Hope to get your reply. thanks.

[nhorman]

The first question I would ask is, why are the read and write fds in the read and write set not readable/writeable? This suggests that something wen't wrong with the connection attempt in those processes. Have you looked at the tcpdumps of the connections when these hung processes occur?