ModemManager: SIGSEGV on OpenWrt 24.10.0-rc2 and SNAPSHOT

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.

Start by reproducing the mmcli crash with luci-proto-modemmanager, kmod-usb-serial-option, and usb-modeswitch on the listed OpenWrt environments and modem hardware. Use the provided kernel and mmcli segmentation-fault logs to identify the failing path; done means GSM modem setup no longer causes SIGSEGV or disconnects the interface.