linux-cve-announce - CVE-2022-50332: video/aperture: Call sysfb

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Message-ID: <2025091555-CVE-2022-50332-a052@gregkh>
Date: Mon, 15 Sep 2025 16:49:09 +0200
From: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To: linux-cve-announce@...r.kernel.org
Cc: Greg Kroah-Hartman <gregkh@...nel.org>
Subject: CVE-2022-50332: video/aperture: Call sysfb_disable() before removing PCI devices

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

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

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

video/aperture: Call sysfb_disable() before removing PCI devices

Call sysfb_disable() from aperture_remove_conflicting_pci_devices()
before removing PCI devices. Without, simpledrm can still bind to
simple-framebuffer devices after the hardware driver has taken over
the hardware. Both drivers interfere with each other and results are
undefined.

Reported modesetting errors [1] are shown below.

---- snap ----
rcu: INFO: rcu_sched detected expedited stalls on CPUs/tasks: { 13-.... } 7 jiffies s: 165 root: 0x2000/.
rcu: blocking rcu_node structures (internal RCU debug):
Task dump for CPU 13:
task:X               state:R  running task     stack:    0 pid: 4242 ppid:  4228 flags:0x00000008
Call Trace:
 <TASK>
 ? commit_tail+0xd7/0x130
 ? drm_atomic_helper_commit+0x126/0x150
 ? drm_atomic_commit+0xa4/0xe0
 ? drm_plane_get_damage_clips.cold+0x1c/0x1c
 ? drm_atomic_helper_dirtyfb+0x19e/0x280
 ? drm_mode_dirtyfb_ioctl+0x10f/0x1e0
 ? drm_mode_getfb2_ioctl+0x2d0/0x2d0
 ? drm_ioctl_kernel+0xc4/0x150
 ? drm_ioctl+0x246/0x3f0
 ? drm_mode_getfb2_ioctl+0x2d0/0x2d0
 ? __x64_sys_ioctl+0x91/0xd0
 ? do_syscall_64+0x60/0xd0
 ? entry_SYSCALL_64_after_hwframe+0x4b/0xb5
 </TASK>
...
rcu: INFO: rcu_sched detected expedited stalls on CPUs/tasks: { 13-.... } 30 jiffies s: 169 root: 0x2000/.
rcu: blocking rcu_node structures (internal RCU debug):
Task dump for CPU 13:
task:X               state:R  running task     stack:    0 pid: 4242 ppid:  4228 flags:0x0000400e
Call Trace:
 <TASK>
 ? memcpy_toio+0x76/0xc0
 ? memcpy_toio+0x1b/0xc0
 ? drm_fb_memcpy_toio+0x76/0xb0
 ? drm_fb_blit_toio+0x75/0x2b0
 ? simpledrm_simple_display_pipe_update+0x132/0x150
 ? drm_atomic_helper_commit_planes+0xb6/0x230
 ? drm_atomic_helper_commit_tail+0x44/0x80
 ? commit_tail+0xd7/0x130
 ? drm_atomic_helper_commit+0x126/0x150
 ? drm_atomic_commit+0xa4/0xe0
 ? drm_plane_get_damage_clips.cold+0x1c/0x1c
 ? drm_atomic_helper_dirtyfb+0x19e/0x280
 ? drm_mode_dirtyfb_ioctl+0x10f/0x1e0
 ? drm_mode_getfb2_ioctl+0x2d0/0x2d0
 ? drm_ioctl_kernel+0xc4/0x150
 ? drm_ioctl+0x246/0x3f0
 ? drm_mode_getfb2_ioctl+0x2d0/0x2d0
 ? __x64_sys_ioctl+0x91/0xd0
 ? do_syscall_64+0x60/0xd0
 ? entry_SYSCALL_64_after_hwframe+0x4b/0xb5
 </TASK>

The problem was added by commit 5e0137612430 ("video/aperture: Disable
and unregister sysfb devices via aperture helpers") to v6.0.3 and does
not exist in the mainline branch.

The mainline commit 5e0137612430 ("video/aperture: Disable and
unregister sysfb devices via aperture helpers") has been backported
from v6.0-rc1 to stable v6.0.3 from a larger patch series [2] that
reworks fbdev framebuffer ownership. The backport misses a change to
aperture_remove_conflicting_pci_devices(). Mainline itself is fine,
because the function does not exist there as a result of the patch
series.

Instead of backporting the whole series, fix the additional function.

The Linux kernel CVE team has assigned CVE-2022-50332 to this issue.


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

	Issue introduced in 6.0.3 with commit cfecfc98a78d97a49807531b5b224459bda877de and fixed in 6.0.6 with commit 25a6688f27ff54f97adf7cce1d7e18c38bf51eb4

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-2022-50332
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/aperture.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/25a6688f27ff54f97adf7cce1d7e18c38bf51eb4