ModemManager: SIGSEGV on OpenWrt 24.10.0-rc2 and SNAPSHOT

[txt-file]

Maintainer: @feckert
Environment:

• Software: OpenWrt 24.10.0-rc2 and SNAPSHOT (as of 2024-12-10)
• hardware:
  • VoCore2 and x86 box
  • ZTE MF190

Description:
I installed the packages luci-proto-modemmanager kmod-usb-serial-option usb-modeswitch. Then via luci I setup the GSM Modem. That worked well with OpenWrt 23.05.5. OpenWrt 24.10.0-rc2 on VoCore2 gave me:

[  219.470723] do_page_fault(): sending SIGSEGV to mmcli for invalid read access from 00000000
[  219.479321] epc = 77eb0b60 in libc.so[77e2a000+b2000]
[  219.484535] ra  = 0040d0bb in mmcli[400000+25000]
[  220.301503] do_page_fault(): sending SIGSEGV to mmcli for invalid read access from 00000000
[  220.310102] epc = 77dc0b60 in libc.so[77d3a000+b2000]
[  220.315320] ra  = 0040d0bb in mmcli[400000+25000]
[  220.631235] do_page_fault(): sending SIGSEGV to mmcli for invalid read access from 00000000
[  220.639833] epc = 77e04b60 in libc.so[77d7e000+b2000]
[  220.645049] ra  = 0040d0bb in mmcli[400000+25000]

Here is an log from x86 box running OpenWrt 24.10.0-rc2 r28161-ea17e958b9:

Tue Dec 10 22:42:29 2024 kern.info kernel: [  365.146532] mmcli[8109]: segfault at 0 ip b7fcc67f sp bf9a4cd4 error 4 in libc.so[b7f83000+5c000] likely on CPU 1 (core 1, socket 0)
Tue Dec 10 22:42:29 2024 kern.info kernel: [  365.147049] Code: 09 f0 a9 80 80 80 80 75 08 83 c3 04 eb d6 83 c3 01 0f b6 03 84 c0 74 bc 39 d0 75 f2 eb b6 56 31 c0 53 8b 5c 24 0c 8b 74 24 10 <0f> b6 0c 03 0f b6 14 06 38 d1 75 0b 83 c0 01 84 d2 75 ed 31 c0 eb
Tue Dec 10 22:42:29 2024 daemon.notice netifd: mwan (8120): stopping network
Tue Dec 10 22:42:29 2024 kern.info kernel: [  365.229764] mmcli[8122]: segfault at 0 ip b7fd067f sp bfe70624 error 4 in libc.so[b7f87000+5c000] likely on CPU 0 (core 0, socket 0)
Tue Dec 10 22:42:29 2024 kern.info kernel: [  365.230282] Code: 09 f0 a9 80 80 80 80 75 08 83 c3 04 eb d6 83 c3 01 0f b6 03 84 c0 74 bc 39 d0 75 f2 eb b6 56 31 c0 53 8b 5c 24 0c 8b 74 24 10 <0f> b6 0c 03 0f b6 14 06 38 d1 75 0b 83 c0 01 84 d2 75 ed 31 c0 eb
Tue Dec 10 22:42:29 2024 daemon.notice netifd: mwan (8120): Segmentation fault (core dumped)
Tue Dec 10 22:42:29 2024 daemon.notice netifd: mwan (8120): couldn't load bearer path: disconnecting anyway
Tue Dec 10 22:42:29 2024 daemon.notice netifd: Interface 'mwan' is now down
Tue Dec 10 22:42:29 2024 kern.info kernel: [  365.262332] mmcli[8127]: segfault at 0 ip b7f3667f sp bfb5b2a4 error 4 in libc.so[b7eed000+5c000] likely on CPU 3 (core 3, socket 0)
Tue Dec 10 22:42:29 2024 kern.info kernel: [  365.262849] Code: 09 f0 a9 80 80 80 80 75 08 83 c3 04 eb d6 83 c3 01 0f b6 03 84 c0 74 bc 39 d0 75 f2 eb b6 56 31 c0 53 8b 5c 24 0c 8b 74 24 10 <0f> b6 0c 03 0f b6 14 06 38 d1 75 0b 83 c0 01 84 d2 75 ed 31 c0 eb

Contact me if you need more information.

[feckert]

I do not have this problem on my used targets. It is difficult to say what the Problem is. I suspect that if it is a problem with the ModemManager, then it is due to the plugin this Modem is using.

• What about other modems? Could you try another modem, is there also a problem there?
• Is it possible to get the output from the command mmcli -m <number>? Or does the call also print the trace?

[txt-file]

I see the error only directly after setting up the connection details via luci. After an poweroff and boot the error is not shown in logread but luci shows the same Error: Network device is not present as before. Restarting the interface in luci doesn't change that.

I tested mmcli after the segfault and after a reboot with unplugging power to completly reset the modem.

• mmcli -m 0 works
• mmcli -m 0 --enable works
• mmcli -m 0 --location-get works
• mmcli -m 0 --3gpp-register-home works

So maybe it is more a luci/netifd/… problem.

I don't have another modem to test. I don't know how to connect fully to mobile network without luci.

root@OpenWrt:~# mmcli --version
mmcli 1.22.0
[…]
root@OpenWrt:~# cat /etc/openwrt_release
DISTRIB_ID='OpenWrt'
DISTRIB_RELEASE='SNAPSHOT'
DISTRIB_REVISION='r28276-3d8d81883f'
DISTRIB_TARGET='x86/generic'
DISTRIB_ARCH='i386_pentium4'
DISTRIB_DESCRIPTION='OpenWrt SNAPSHOT r28276-3d8d81883f'
DISTRIB_TAINTS=''
root@OpenWrt:~#

[feckert]

Which modem are you using?
Can you paste the output mmcli -m 0 here?

To narrow down the problem further, you can also start the ModemManager in DEBUG mode.
Please change the following line LOG_LEVEL=INFO in the /etc/init.d/modemmanager file on your target to LOG_LEVEL=DEBUG so we can get more logs.

But I rather suspect that this is a problem of the ModemManager and needs to be fixed in the upstream repository of the ModemManager.