From the version of the Linux kernel that includes the text console , which provides the ability to scroll text backward (CONFIG_VGACON_SOFT_SCROLLBACK). The code has been removed due to the presence of errors that had no maintainer to fix because there was no one overseeing the development of vgacon.
In the summer, a vulnerability was identified in vgacon (CVE-2020-14331), which could lead to a buffer overflow due to inadequate checks for available memory in the scroll buffer. The vulnerability attracted the attention of developers, who organized fuzzing testing for the vgacon code in .
. Additional checks revealed several similar issues in the vgacon code, as well as problems in the software implementation of scrolling in the fbcon driver. Unfortunately, the problematic code has long been left without support, presumably because developers have switched to using graphical consoles and text consoles have fallen out of favor (people continue to use the vgacon and fbcon consoles, but they have not been the main interface of the kernel for decades, and such advanced features as built-in scrolling in the driver (Shift+PageUp/PageDown) are likely to be little in demand).
Due to this, Linus Torvalds decided not to attempt to support the unsupported code and simply remove it. If any users find this functionality necessary, the code for supporting scrolling in the console will be returned to the kernel as soon as a maintainer is found who is ready to take over its support.
Source: opennet.ru
