CVE-2022-48627: vt: fix memory overlapping when deleting chars in the buffer

CVE-2022-48627: vt: fix memory overlapping when deleting chars in the buffer

[Greg Kroah-Hartman]

Description
===========

In the Linux kernel, the following vulnerability has been resolved:

vt: fix memory overlapping when deleting chars in the buffer

A memory overlapping copy occurs when deleting a long line. This memory
overlapping copy can cause data corruption when scr_memcpyw is optimized
to memcpy because memcpy does not ensure its behavior if the destination
buffer overlaps with the source buffer. The line buffer is not always
broken, because the memcpy utilizes the hardware acceleration, whose
result is not deterministic.

Fix this problem by using replacing the scr_memcpyw with scr_memmovew.

The Linux kernel CVE team has assigned CVE-2022-48627 to this issue.


Affected and fixed versions
===========================

	Issue introduced in 3.7 with commit 81732c3b2fed and fixed in 5.10.132 with commit bfee93c9a6c3
	Issue introduced in 3.7 with commit 81732c3b2fed and fixed in 5.15.56 with commit 57964a571025
	Issue introduced in 3.7 with commit 81732c3b2fed and fixed in 5.18.13 with commit 14d2cc21ca62
	Issue introduced in 3.7 with commit 81732c3b2fed and fixed in 5.19 with commit 39cdb68c64d8

Please see https://www.kernel.org or a full list of currently supported
kernel versions by the kernel community.

Unaffected versions might change over time as fixes are backported to
older supported kernel versions.  The official CVE entry at
	https://cve.org/CVERecord/?id=CVE-2022-48627
will be updated if fixes are backported, please check that for the most
up to date information about this issue.


Affected files
==============

The file(s) affected by this issue are:
	drivers/tty/vt/vt.c


Mitigation
==========

The Linux kernel CVE team recommends that you update to the latest
stable kernel version for this, and many other bugfixes.  Individual
changes are never tested alone, but rather are part of a larger kernel
release.  Cherry-picking individual commits is not recommended or
supported by the Linux kernel community at all.  If however, updating to
the latest release is impossible, the individual changes to resolve this
issue can be found at these commits:
	https://git.kernel.org/stable/c/bfee93c9a6c395f9aa62268f1cedf64999844926
	https://git.kernel.org/stable/c/57964a5710252bc82fe22d9fa98c180c58c20244
	https://git.kernel.org/stable/c/14d2cc21ca622310babf373e3a8f0b40acfe8265
	https://git.kernel.org/stable/c/39cdb68c64d84e71a4a717000b6e5de208ee60cc