Crashing just because of lack of uplink?

[doremifajb]

Hello! I recently flashed 22.3 to Edgerouter X. I'm still working on it, in order to replace fritzbox 4020 with it.
I noticed that something weird happens when I disconnect WAN uplink: I had OpenNDS on br-lan.11, and it crashed (I wrote the creator of OpenNDS about it) In order to reproduce it, I pulled WAN cable again. This time OpenNDS did not crash (it did restart), but something else looks like crashing.

Sun Dec  4 22:06:49 2022 kern.info kernel: [257049.733379] do_page_fault(): sending SIGSEGV to dnsmasq for invalid read access from 56cf9300
Sun Dec  4 22:06:49 2022 kern.info kernel: [257049.750648] epc = 555d57c9 in dnsmasq[555c0000+43000]
Sun Dec  4 22:06:49 2022 kern.info kernel: [257049.760936] ra  = 555d5761 in dnsmasq[555c0000+43000]

I don't really understand why losing uplink has to cause something like this. Is it normal for 22.3 ? I used to work on a new router off-line till I need to download something, and nothing happened while it was offline. (well, back then I wasn't reading log)

I would appreciate your hint! As it is, I'm pretty afraid of using ERX.

[bluewavenet]

@doremifajb

I don't really understand why losing uplink has to cause something like this. Is it normal for 22.3 ?

For the benefit of others (I already discussed with @doremifajb via email), this is caused by FW4 doing a restart on a hotplug event (eg unplugging and replugging the wan ethernet).

By default openNDS does a restart if FW4 does a restart. Then in turn openNDS tells dnsmasq to restart. For some fluke reason dnsmasq decided to crash on one occasion.

This behaviour is mitigated in the upcoming v9.10.0 openNDS release as a part of continuing nftables support and FW4 compatibility improvements.