CVE-2026-80786: fbdev: Wrap user-invoked calls to fb_set_var() in helper

CVE-2026-80786: fbdev: Wrap user-invoked calls to fb_set_var() in helper

[Greg Kroah-Hartman]

From: Greg Kroah-Hartman <gregkh@kernel.org>

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

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

fbdev: Wrap user-invoked calls to fb_set_var() in helper

Handle fbcon during display updates in fb_set_var_from_user(). Check
with fbcon if the mode change is possible, update hardware state and
finally update fbcon. Update all callers.

Only the FBIOPUT_VSCREENINFO ioctl currently does all steps. Other
mode-changes callers in sysfs and driver code are missing fbcon-related
steps.

With the new helper, ps3fb and sh_mobile_lcdcfb no longer maintain
fbcon state themselves.

The Linux kernel CVE team has assigned CVE-2026-80786 to this issue.


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

	Fixed in 7.1.11 with commit 07f7e46833f71472e30da54a50dacdf48521bdd3
	Fixed in 7.2 with commit 6f611e5e5f3327cf2e2daabe6ee5acac58cc784e

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-2026-80786
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/core/fb_chrdev.c
	drivers/video/fbdev/core/fbcon.c
	drivers/video/fbdev/core/fbmem.c
	drivers/video/fbdev/core/fbsysfs.c
	drivers/video/fbdev/ps3fb.c
	drivers/video/fbdev/sh_mobile_lcdcfb.c
	include/linux/fb.h


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/07f7e46833f71472e30da54a50dacdf48521bdd3
	https://git.kernel.org/stable/c/6f611e5e5f3327cf2e2daabe6ee5acac58cc784e