Bug 513850

Summary:	cat /dev/urandom from konsole freeze the whole desktop (maybe for notification flood?)
Product:	[Frameworks and Libraries] frameworks-knotifications	Reporter:	andrew <fandrew>
Component:	general	Assignee:	kdelibs bugs <kdelibs-bugs-null>
Status:	REPORTED ---
Severity:	normal	CC:	elijaharagonmorgan, kdelibs-bugs-null
Priority:	NOR
Version First Reported In:	unspecified
Target Milestone:	---
Platform:	Other
OS:	Linux
Latest Commit:		Version Fixed/Implemented In:
Sentry Crash Report:

Description andrew 2025-12-26 20:35:09 UTC

SUMMARY

When running commands that output raw binary data (specifically cat /dev/urandom) inside Konsole, the terminal emulator interprets specific byte sequences as valid escape codes for Desktop Notifications. Because /dev/urandom generates data rapidly, this results in a high-frequency flood of notifications.

Within seconds, this overwhelms the notification daemon/Plasma Shell, causing the entire desktop environment to freeze. The system becomes unresponsive to input (e.g., the Super/Meta key does not function), and journalctl shows no specific error logs regarding the crash, likely due to the nature of the resource exhaustion/input lock.

STEPS TO REPRODUCE
Open Konsole in a Plasma Wayland session.
Run the command: cat /dev/urandom
Allow the command to run for a few seconds.

OBSERVED RESULT
Konsole begins parsing the random binary data. "Phantom" notifications appear repeatedly and rapidly on the screen. Within a few seconds, the entire graphical session (Plasma/KWin) freezes. Keyboard shortcuts (like the Super key) stop responding, and the system appears to be under a Denial of Service state caused by the notification spam.

EXPECTED RESULT
Should not freeze the entire desktop because of these notifications.

SOFTWARE/OS VERSIONS
[andrew@arch ~]$ kinfo
Operating System: Arch Linux
KDE Plasma Version: 6.5.4
KDE Frameworks Version: 6.21.0
Qt Version: 6.10.1
Kernel Version: 6.18.1-zen1-2-zen (64-bit)
Graphics Platform: Wayland
Processors: 16 × AMD Ryzen 7 7800X3D 8-Core Processor
Memory: 32 GiB of RAM (31.0 GiB usable)
Graphics Processor: AMD Radeon RX 7900 XTX

ADDITIONAL INFORMATION
Even though there are many notifications, they don’t seem excessive, yet the desktop remains frozen for a long time relative to the number of notifications.

cat /dev/urandom is just an extreme example. In fact, this also happened to me when I accidentally ran cat without properly handling stdout, and my entire desktop froze for a long time (30–60 seconds).

Comment 1 elijaharagonmorgan 2025-12-27 18:46:41 UTC

Which terminal did you use?
Do you think the issue lies in the notification daemon or the console incorrectly interpreting the binary.

Comment 2 andrew 2025-12-27 18:54:00 UTC

(In reply to elijaharagonmorgan from comment #1)
> Which terminal did you use?
> Do you think the issue lies in the notification daemon or the console
> incorrectly interpreting the binary.

Which terminal did you use? konsole with bash

I don’t think this is a problem with the terminal itself. Regardless of who creates the notification—the notification daemon or whoever is involved—it must not block the entire desktop.

cat /dev/urandom is just a practical example, but it can happen with any kind of output, for example by doing cat dog.png.

There are certainly other applications that could cause the same kind of bug by creating notifications, but I was able to reproduce it from Konsole using that cat command in a fairly deterministic way, so that it can be tested by others.