netdev - SOCK_STREAM TCP: send() returns success even when other side responded with RST packet

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-next>] [day] [month] [year] [list]

Date:	Tue, 19 Feb 2013 02:02:12 -0500 (EST)
From:	Tomas Hozza <thozza@...hat.com>
To:	netdev@...r.kernel.org
Subject: SOCK_STREAM TCP: send() returns success even when other side
 responded with RST packet

Hi.

I was advised to forward my networking Kernel related Bug here
so it can get fixed much faster. Here is the Bug description
copied from Red Hat Bugzilla (https://bugzilla.redhat.com/show_bug.cgi?id=912382):

Description of problem:
I'm using SOCK_STREAM TCP sockets. Imagine server-client application.
- Server will accept connection from client.
- Client sends some data to server -> server receives data.
- Client then half-closes the TCP connection using shutdown(fd, SHUT_WR).
- Client waits for some data from the server.
- Server sends some data to client -> client receives data.
- Client exits and closes the socket.
- After some time server tries to send some data to the client.
- The first send() call returns success even the Client's response is RST.

Version-Release number of selected component (if applicable):
3.7.7-201.fc18.x86_64
3.7.8-202.fc18.x86_64

How reproducible:
always

Steps to Reproduce:
1. download attached client/server sources.
2. compile server: # gcc tcp_server.c -o server
3. compile client: # gcc tcp_client.c -o client
4. run the server: # ./server
5. run the client: # ./client

Actual results:
Server started...
Created SOCK_STREAM socket
Bound to localhost:6666
waiting for connection...
Client connected!
Waiting for some data from client
Received: "MSG from client"
Received EOF
Sending msg to client: "MSG from server"
sleep(5)
Sending 1 msg to client: "MSG from server"
try #1 send() result: (0) Success
Sending 2 msg to client: "MSG from server"
try #2 send() result: (32) Broken pipe
Server exiting...

Expected results:
Server should fail to send() data right after sleep().

Server started...
Created SOCK_STREAM socket
Bound to localhost:6666
waiting for connection...
Client connected!
Waiting for some data from client
Received: "MSG from client"
Received EOF
Sending msg to client: "MSG from server"
sleep(5)
Sending 1 msg to client: "MSG from server"
try #1 send() result: (32) Broken pipe
Server exiting...

Additional info:
RST answer means that data were NOT delivered. Therefore the very
first send() call after server sleep() should fail!

Regards,

Tomas Hozza
View attachment "tcp_server.c" of type "text/x-csrc" (2474 bytes)

View attachment "tcp_client.c" of type "text/x-csrc" (1694 bytes)