CVE-2026-80579: fbdev: clear fb_info->mode before deleting a videomode

CVE-2026-80579: fbdev: clear fb_info->mode before deleting a videomode

[Greg Kroah-Hartman]

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

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

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

fbdev: clear fb_info->mode before deleting a videomode

fb_set_var() can delete a mode from info->modelist when userspace
passes FB_ACTIVATE_INV_MODE through FBIOPUT_VSCREENINFO. The code
checks that the mode being deleted is not the current info->var and
that fbcon is not using it, but it does not check fb_info->mode.

fb_info->mode may still point into the modelist entry being deleted.
If the entry is freed, later mode sysfs reads through show_mode() can
dereference a stale pointer.

Clear fb_info->mode before calling fb_delete_videomode() when it
matches the mode being removed.

The Linux kernel CVE team has assigned CVE-2026-80579 to this issue.


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

	Fixed in 7.1.10 with commit ce7fef961c63229b22dec415fb988899f479d61f
	Fixed in 7.2 with commit 95e647d2a5304a8fd11f1ba3c8502de700650131

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-2026-80579
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/fbmem.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/ce7fef961c63229b22dec415fb988899f479d61f
	https://git.kernel.org/stable/c/95e647d2a5304a8fd11f1ba3c8502de700650131