linux-kernel - Re: disappearing listen()ed SO_REUSEPORT sockets across fork() when using epoll

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Date:	Mon, 25 Nov 2013 13:05:05 -0500
From:	Jason Baron <jbaron@...mai.com>
To:	Shawn Landden <shawnlandden@...il.com>
CC:	linux-fsdevel@...r.kernel.org, linux-kernel@...r.kernel.org,
	Tom Herbert <therbert@...gle.com>
Subject: Re: disappearing listen()ed SO_REUSEPORT sockets across fork() when
 using epoll

On 11/22/2013 12:53 PM, Shawn Landden wrote:
> Hello, when running the attached program on 3.12 child processes
> are missing a socket fd opened, set with SO_REUSEPORT, listen()ed to,
> and added to epoll_ctl().
> 
> This is the output I get when pointing "wget http://localhost:5555/"
> at the attached program:
> 
> main PID 31591
> PID 31634 started
> PID 31634 accept()ed connection
> PID 31635 started
> PID 31636 started
> PID 31635 accept() failed: Bad file descriptor
> PID 31636 accept() failed: Bad file descriptor
> PID 31634 accept()ed connection
> PID 31634 accept()ed connection
> PID 31634 accept()ed connection
> PID 31634 accept()ed connection
> 
> 
> While I would expect something like:
> 
> main PID 31591
> PID 31634 started
> PID 31634 accept()ed connection
> PID 31635 started
> PID 31636 started
> PID 31635 accept()ed connection
> PID 31636 accept()ed connection
> 
> -more new processes, but inversely proportional to number of listening processes
> -accept() always returns successfully
> 
> 

The 'close(sockfd);' looks to be racing with the accept() calls. Removing seems
to get the result you are looking for.

Thanks,

-Jason

--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/