DietPi-Software | MPD: Crash loading media with album art through Samba

[seniorgod]

Creating a bug report/issue

Required Information

G_DIETPI_VERSION_CORE=7
G_DIETPI_VERSION_SUB=5
G_DIETPI_VERSION_RC=2
G_GITBRANCH='master'
G_GITOWNER='MichaIng'

debian version 11.0

Linux DietPi 3.10.38 #22 SMP PREEMPT Fri Dec 22 10:45:41 IST 2017 armv7l GNU/Linux

Sparky SBC

Additional Information (if applicable)

mpd installed from dietpi software list

Steps to reproduce

since update to DietPi 7.5.x i faces problems with mpd
i stripped down everything in mpd to find out what it is.
mpd runs stable as long if i only load a playlists including radio streams, meaning playing mp3 from public url from local radio stations.
The problems occur when i start to read in my local music.
I read in music directly via smb
music_directory "smb://192.168.178.2/medien_read_only/squeeze
when i update mpd via the update command to read in music directory, it starts to update the music directory add the music to the library. During the update process my iOS client for mpd starts to update/communicate with mpd. When that's start mpd crashes:

Sep 04 12:18 : client: [18] command returned 0
Sep 04 12:18 : client: [19] process command "status"
Sep 04 12:18 : client: [19] command returned 0
Sep 04 12:18 : client: [18] process command "albumart "FLAC_20101126/Tim Bendzko/[2019] Filter/" "0""
Freed frame ../../source3/param/loadparm.c:2713, expected ../../source3/param/loadparm.c:3939.
Freed frame ../../source3/libsmb/libsmb_context.c:139, expected ../../source3/param/loadparm.c:3939.
Freed frame ../../source3/libsmb/libsmb_context.c:47, expected ../../source3/param/loadparm.c:3939.
no talloc stackframe at ../../source3/param/loadparm.c:847, leaking memory
Freed frame ../../source3/libsmb/libsmb_context.c:744, expected ../../source3/param/loadparm.c:2645.
Bad talloc magic value - unknown value

perhaps it relates to a "album art" error which is discussed at GitHub at the mpd project

when i start mpd again, i have to delete the DB and and comment the music directory in order to get back a stable mpd

Expected behaviour

mpd should read in my music directory from smb like before

[seniorgod]

since mpd 0.22.11. there seem to be a fix

....
ver 0.22.11 (2021/08/24)

• protocol
  • fix "albumart" crash
    ......

is it possible to update in Dietpi 7.5.2 to mpd. 0.22.11 ?

[MichaIng]

We install the package from Debian: https://packages.debian.org/bullseye/mpd
So we'd need to report this bug in ask for cherry picking this patch into stable Debian. I guess it is a specific album art type or affects only FLAC or so, that it hasn't been recognised yet: https://bugs.debian.org/cgi-bin/pkgreport.cgi?src=mpd

[MichaIng]

Hmm, v0.22.11 fixed a bug that was introduced with a feature v0.22.10:

• MPD 0.22.10 'albumart' segfaults MusicPlayerDaemon/MPD#1224
• Albumart segfault MusicPlayerDaemon/MPD#1225
• MusicPlayerDaemon/MPD@cfe024e

So this is not the right fix. Were these the issues you meant or which one do you mean?

Actually the final issue is with Samba/libsmbclient. Check for Bad talloc magic value - unknown value in search machines, and you'll get a lot of matching results around Samba. It uses libtalloc2 for memory allocation and something seems to be going wrong, leading to the logged memory leaks. But of course it could also be related to the way MPD invokes libsmbclient. Also the proceeding Freed frame logs come from MPD, while most deal with code in libsmb_context.c.

Another factor in your case is that Sparky SBC uses a very old Linux v3.10.38. Not sure, but for people with deeper knowledge for debugging it, this may be an important info as well.

I think to first get some clarification where exactly it is coming from, which MPD code is called and how it invokes libsmbclient with this FLAC file albumart, it makes sense to report this at the MPD repository: https://github.com/MusicPlayerDaemon/MPD/issues

[seniorgod]

Thanks for the hint to smbclient
I connected the external drive via smb with Dietpi-drive-manager to the filesystem.
I changed the config of mpd to use the local directory (connected via smb)
That solved the problem.

thanxs

[MichaIng]

Ah, that is a good workaround indeed 👍.