Re: [PATCH] usbip: Close all listening sockets in request workers

[Shuah Khan <skhan@linuxfoundation.org>]

On 11/12/26 19:37, raoxu wrote:
> Hi Shuah,
> 
> Thanks for the review.
> 
> I found this while reviewing the listening socket handling across fork() in
> usbipd.c, and then reproduced the issue with the unmodified usbipd binary on
> two UOS test machines.
> 
> Both machines have usbip 2.0+6.5.10-2 installed, with usbipd located at
> /usr/sbin/usbipd. This package contains the original listener handling.
> 
> I used separate test ports to avoid interfering with the default USB/IP
> service.
> 
> On 10.20.12.188, the reproduction steps were:
> 
> 1. Start usbipd as root with both IPv4 and IPv6 listeners:
> 
>         sudo /usr/sbin/usbipd -d -4 -6 -t 43241
> 
> 2. From a client machine, establish an IPv4 TCP connection and keep it open
>     without sending a USB/IP request:
> 
>         python3 -c 'import socket,time; s=socket.create_connection(("10.20.12.188",43241)); time.sleep(300)'
> 
> 3. Terminate only the main usbipd process with SIGTERM, leaving the worker
>     running.

You removed all the context from the thread :(

In the following path in process_request(), child exits after
handling the pdu - all open fds get closed.

        childpid = fork();
         if (childpid == 0) {
                 close(listenfd);
                 recv_pdu(connfd);
                 exit(0);
         }

How does the problem you are describing happen in the normal
use-case when a child exits after handling the request. If
it doesn't there is no need for this change you are proposing.

thanks,
-- Shuah