On Mon, Jan 8, 2024 at 09:37 AM, David Ranch wrote:
Interesting.. if your custom built Pat really isn't linked to AX.25 at all yet the panic is coming from Pat.. this means Pat is doing something very bad.
? Well, Pat probably isn't doing anything bad; you have to consider that /usr/bin/beacon triggers this as well. ?It's unlikely that separate bugs in both of those programs trigger the same crash. ?It's most likely a bug in the kernel, IMHO.
Ok.. sounds like a packaging miss but regardless, it sounds like your issue is still on the Linux AX.25 stack.
After I posted my note yesterday, I pulled down the source for Pat and compiled it on my test Pi. ?The recommend build process includes a step where the build scripts grab a copy of libax25, builds and statically links it. ?It's not a packaging miss; Martin decided to statically include a version of libax25 code, one that presumably has fixes he finds useful. ?From the non-preferred build method:
WARNING: No static libax25 library available.
? Linking against shared library instead. To fix
? this issue, set CGO_LDFLAGS to the full path of
? libax25.a, or run 'make.bash libax25' to download
? and compile libax25-0.0.12-rc4 in .build/
?
I'm currently aware of two ways to break the Linux kernel. ?
?? 1. I'm not 100% sure this is reproducible for all current kernel versions but I CAN reproduce this on Ubuntu 20.04 running 5.15.0.? Bring up your AX.25 stack with a
I tested the first bug by connecting to a remote node near by and connecting back to my -10 RMS server on the Pi. ?The Winlink banner came a cross and I issued the RMS help command, which sent about 2kb of data total through the remote node and back to my Pi. ?No crash or any notable issues.
?? 2. "Address already in use": From the Linux machines console (NOT SSHing into the AX.25 enabled LInux host) and using the "call" program, create an outbound
I tested the second bug, but I did use a ssh connection. ?You can simply escape the sequence by sending ~~. ; unfortunately, my node is headless and my serial console is busy waiting for a kernel panic, so I didn't have a console option. ?When I terminated the session, my terminal broke back to the Pi (e.g. the ssh connection was still established), but netstat did not show any hung connections. ?Be that as it may, I have seen this bug many times in older versions of Raspbian, some 4-5 years ago.
? Thanks
? Mike
