Subject: CVE-2024-26777: fbdev: sis: Error out if pixclock equals zero

From: Greg Kroah-Hartman <[email-masked]>

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

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

fbdev: sis: Error out if pixclock equals zero

The userspace program could pass any values to the driver through
ioctl() interface. If the driver doesn't check the value of pixclock,
it may cause divide-by-zero error.

In sisfb_check_var(), var->pixclock is used as a divisor to caculate
drate before it is checked against zero. Fix this by checking it
at the beginning.

This is similar to CVE-2022-3061 in i740fb which was fixed by
commit 15cf0b8.

The Linux kernel CVE team has assigned CVE-2024-26777 to this issue.

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

	Fixed in 4.19.308 with commit 84246c35ca34
	Fixed in 5.4.270 with commit 6db07619d173
	Fixed in 5.10.211 with commit cd36da760bd1
	Fixed in 5.15.150 with commit df6e2088c6f4
	Fixed in 6.1.80 with commit f329523f6a65
	Fixed in 6.6.19 with commit 99f1abc34a6d
	Fixed in 6.7.7 with commit 1d11dd3ea5d0
	Fixed in 6.8 with commit e421946be7d9

Please see https://www.kernel.org for 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-2024-26777
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/video/fbdev/sis/sis_main.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/84246c35ca34207114055a87552a1c4289c8fd7e
	https://git.kernel.org/stable/c/6db07619d173765bd8622d63809cbfe361f04207
	https://git.kernel.org/stable/c/cd36da760bd1f78c63c7078407baf01dd724f313
	https://git.kernel.org/stable/c/df6e2088c6f4cad539cf67cba2d6764461e798d1
	https://git.kernel.org/stable/c/f329523f6a65c3bbce913ad35473d83a319d5d99
	https://git.kernel.org/stable/c/99f1abc34a6dde248d2219d64aa493c76bbdd9eb
	https://git.kernel.org/stable/c/1d11dd3ea5d039c7da089f309f39c4cd363b924b
	https://git.kernel.org/stable/c/e421946be7d9bf545147bea8419ef8239cb7ca52