[SRU] no WiFi card, ends with segfault

[psl]

[ Impact ]

The usage of horst is not affect and horst is perfectly usable on a system where a wifi hardware is present.
But if any user who does not have a wifi hardware executes horst then it will segfault which is unexpected and the user will not expect a segfault.
This ultimateley affects the user experience.

[ Test Plan ]

There needs to be two tests:
1. Execute horst on a system where wifi hardware is not present to confirm the segfault is fixed.
2. Execute horst on a system where wifi hardware is present and then horst should work normally.

[ Where problems could occur ]

The patch checks if the wifi interface, which horst will try to use, is present on the system or not. It will then exit gracefully if the interface is not present instead of trying to use a non-existent device. This is not changing any other part of the code and the check is added at the beginnning. So, there is very minimum chance of it affecting the normal functioning of horst.

[ Other Info ]

* All versions from Focal are affected by this.

[ Original Bug Description ]

Ubuntu 22.04.3, amd64

PC has no WiFi card. Horst crashes:

$ horst -v
5.1 (build date: Nov 28 2021 18:51:58)

$ horst
failed to find nl80211
Segmentation fault (core dumped)

$ gdb horst
...
(gdb) run
Starting program: /usr/sbin/horst
[Thread debugging using libthread_db enabled]
Using host libthread_db library "/lib/x86_64-linux-gnu/libthread_db.so.1".
failed to find nl80211

Program received signal SIGSEGV, Segmentation fault.
0x00007ffff7e40bc6 in genl_family_get_id () from /lib/x86_64-linux-gnu/libnl-genl-3.so.200
(gdb)

[Sudip Mukherjee (sudipmuk)]

I have now tested and I can reproduce the problem in all releases from Noble, Mantic, Lunar, Jammy and Focal.

[Sudip Mukherjee (sudipmuk)]

debdiff for Noble attached.

[Sudip Mukherjee (sudipmuk)]

Debdiff for Mantic attached.

[Sudip Mukherjee (sudipmuk)]

Debdiff for Lunar attached.

[Sudip Mukherjee (sudipmuk)]

Debdiff for Jammy attached.

[Sudip Mukherjee (sudipmuk)]

Debdiff for Focal attached.

[Aaron Rainbolt (arraybolt3)]

Noble packaging looks good to me, tsimonq2 has uploaded it.

[Launchpad Janitor (janitor)]

This bug was fixed in the package horst - 5.1-3ubuntu1

---------------
horst (5.1-3ubuntu1) noble; urgency=medium

  * Fix segfault by exiting if interface does not exist. (LP: #2045986)

 -- Sudip Mukherjee <email address hidden> Sun, 31 Dec 2023 21:07:23 +0000

[Steve Langasek (vorlon)]

Description: Highly Optimized Radio Scanning Tool
 horst is a small, lightweight IEEE802.11 WLAN analyzer with a text
 interface. [...]

The SRU justification given is:

> But if any user who does not have a wifi hardware executes horst then it
> will segfault which is unexpected and the user will not expect a segfault.
> This ultimateley affects the user experience.

The user experience before this patch is an error message and a segfault.
The user experience after this patch is a different error message and (hopefully) no segfault.

This is not a significant improvement to the user experience for a package installed on a system where it is completely useless and in my view does not meet the threshold of an SRU.

[Steve Langasek (vorlon)]

An upload of horst to mantic-proposed has been rejected from the upload queue for the following reason: "low-priority fix, rejecting for SRU".

[Steve Langasek (vorlon)]

An upload of horst to lunar-proposed has been rejected from the upload queue for the following reason: "low-priority fix, rejecting for SRU".

[Steve Langasek (vorlon)]

An upload of horst to jammy-proposed has been rejected from the upload queue for the following reason: "low-priority fix, rejecting for SRU".