[pulseaudio-tickets] [Bug 96873] New: tcp transport always fails: PULSE_SERVER=127.0.0.1 src/pacat, Connection failure: Connection terminated

Sat Jul 9 20:40:10 UTC 2016

https://bugs.freedesktop.org/show_bug.cgi?id=96873

            Bug ID: 96873
           Summary: tcp transport always fails: PULSE_SERVER=127.0.0.1
                    src/pacat, Connection failure: Connection terminated
           Product: PulseAudio
           Version: unspecified
          Hardware: Other
                OS: All
            Status: NEW
          Severity: normal
          Priority: medium
         Component: core
          Assignee: pulseaudio-bugs at lists.freedesktop.org
          Reporter: slyfox at inbox.ru
        QA Contact: pulseaudio-bugs at lists.freedesktop.org
                CC: lennart at poettering.net

Noticed breakage on real applications like mpv and other media apps.

PA used to work but I'm not sure what exactly changed in my environment.

Currently pulseaudio over TCP is broken on the following versions:
    7.1, 8.0, 9.0.

How to reproduce:
=================

1. run pulseaudio server on one terminal:
    $ pulseaudio -vvv

2. run client with PULSE_SERVER=127.0.0.1 set
    dev/git/pulseaudio $ PULSE_SERVER=127.0.0.1 src/pacat

Analysis:
=========

1. strace shows there is a failed sendmsg(cmsg_type=SCM_CREDENTIALS) on TCP
socket.

    $ PULSE_SERVER=127.0.0.1 strace -f src/pacat

    ppoll([{fd=3, events=POLLIN}, {fd=13, events=POLLIN|POLLOUT}, {fd=0,
events=POLLIN}, {fd=5, events=POLLIN}], 4, {29, 999755000}, NULL, 8) = 1
([{fd=13, revents=POLLOUT}], left {29, 999753448})
    write(4, "W", 1)                        = 1
    sendmsg(13, {msg_name(0)=NULL,
msg_iov(1)=[{"\0\0\1\24\377\377\377\377\0\0\0\0\0\0\0\0\0\0\0\0", 20}],
msg_controllen=32, {cmsg_len=28, cmsg_level=SOL_SOCKET,
cmsg_type=SCM_CREDENTIALS{pid=5412, uid=1000, gid=100}}, msg_flags=0},
MSG_NOSIGNAL) = -1 EINVAL (Invalid argument)
    write(2, "Connection failure: Connection t"..., 42Connection failure:
Connection terminated
) = 42
    write(4, "W", 1)                        = 1
    write(4, "W", 1)                        = 1
    close(13)

server side sees it as abrupt connection:
    I: [pulseaudio] socket-server.c: TCP connection accepted by tcpwrap.
    I: [pulseaudio] client.c: Created 8 "Native client (TCP/IP client from
127.0.0.1:46160)"
    I: [pulseaudio] client.c: Freed 8 "Native client (TCP/IP client from
127.0.0.1:46160)"
    I: [pulseaudio] protocol-native.c: Connection died.

Looking at the code there is a few functions that assume UNIX sockets:

    pa_iochannel_write_with_creds()
    pa_iochannel_write_with_fds()

I've added a few asserts there to explicitly state the invariant of UNIX socket
being handled:

    diff --git a/src/pulsecore/iochannel.c b/src/pulsecore/iochannel.c
    index e62750b..a85de41 100644
    --- a/src/pulsecore/iochannel.c
    +++ b/src/pulsecore/iochannel.c
    @@ -313,2 +313,3 @@ ssize_t pa_iochannel_write_with_creds(pa_iochannel*io,
const void*data, size_t l
         pa_assert(io->ofd >= 0);
    +    pa_assert(pa_iochannel_creds_supported(io));

    @@ -365,2 +366,3 @@ ssize_t pa_iochannel_write_with_fds(pa_iochannel*io,
const void*data, size_t l,
         pa_assert(nfd <= MAX_ANCIL_DATA_FDS);
    +    pa_assert(pa_iochannel_creds_supported(io));

That allows to get exact backtrace how crash happens:

    dev/git/pulseaudio $ PULSE_SERVER=127.0.0.1 src/pacat

    Assertion 'pa_iochannel_creds_supported(io)' failed at
pulsecore/iochannel.c:314, function     pa_iochannel_write_with_creds().
Aborting.
    Aborted (core dumped)

    dev/git/pulseaudio $ gdb src/.libs/pacat core.29381

    #0  0x00007f814e4591c8 in __GI_raise (sig=sig at entry=6) at
../sysdeps/unix/sysv/linux/raise.c:54
    54      ../sysdeps/unix/sysv/linux/raise.c: No such file or directory.
    (gdb) bt
    #0  0x00007f814e4591c8 in __GI_raise (sig=sig at entry=6) at
../sysdeps/unix/sysv/linux/raise.c:54
    #1  0x00007f814e45a61a in __GI_abort () at abort.c:89
    #2  0x00007f815164dc5e in pa_iochannel_write_with_creds (io=0xb08830,
data=0xb08aa8, l=20, ucred=0xb0a944)
        at pulsecore/iochannel.c:314
    #3  0x00007f815166958a in do_write (p=0xb08a60) at pulsecore/pstream.c:777
    #4  0x00007f8151666fc1 in do_pstream_read_write (p=0xb08a60) at
pulsecore/pstream.c:258
    #5  0x00007f8151667358 in io_callback (io=0xb08830, userdata=0xb08a60) at
pulsecore/pstream.c:304
    #6  0x00007f815164ceff in callback (m=0xb02748, e=0xb08a10, fd=13,
f=PA_IO_EVENT_OUTPUT, userdata=0xb08830)
        at pulsecore/iochannel.c:158
    #7  0x00007f81518d922a in dispatch_pollfds (m=0xb026f0) at
pulse/mainloop.c:655
    #8  0x00007f81518da011 in pa_mainloop_dispatch (m=0xb026f0) at
pulse/mainloop.c:898
    #9  0x00007f81518da18e in pa_mainloop_iterate (m=0xb026f0, block=1,
retval=0x7fff98276708) at pulse/mainloop.c:929
    #10 0x00007f81518da1ee in pa_mainloop_run (m=0xb026f0,
retval=0x7fff98276708) at pulse/mainloop.c:944
    #11 0x0000000000406e43 in main (argc=1, argv=0x7fff98276a28) at
utils/pacat.c:1202

-- 
You are receiving this mail because:
You are the assignee for the bug.
You are the QA Contact for the bug.
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <https://lists.freedesktop.org/archives/pulseaudio-bugs/attachments/20160709/1243e861/attachment.html>