In the Linux kernel, support for scrolling text was removed from the text console | VPS and VPN
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In the Linux kernel, support for scrolling text was removed from the text console

Removed text scrolling code from the text console implementation in the Linux kernel (CONFIG_VGACON_SOFT_SCROLLBACK). The code was removed due to the presence of errors, which there was no one to fix due to the lack of a maintainer overseeing the development of vgacon.

In the summer, a vulnerability (CVE-2020-14331) was identified and fixed in vgacon that could lead to a buffer overflow due to the lack of proper checks for the availability of memory in the scroll buffer. The vulnerability attracted the attention of developers who organized fuzzing testing of the vgacon code in syzbot.

Additional checks revealed several more similar problems in the vgacon code, as well as problems in the software implementation of scrolling in the fbcon driver. Unfortunately, the problematic code has been left unattended for a long time, presumably due to the fact that the developers switched to using graphical consoles and text consoles went out of use (people continue to use the vgacon and fbcon consoles, but they have not been the main kernel interface for decades and such extended features such as scrolling built into the driver (Shift + PageUp / PageDown) are presumably little in demand).

In this regard, Linus Torvalds decided not to try to maintain the unclaimed code, but simply to delete it. If there are users who need this functionality, the code for supporting scrolling in the console will be returned to the kernel as soon as there is a maintainer ready to take its maintenance into their own hands.


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