Subject: CVE-2021-47063: drm: bridge/panel: Cleanup connector on bridge detach

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

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

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

drm: bridge/panel: Cleanup connector on bridge detach

If we don't call drm_connector_cleanup() manually in
panel_bridge_detach(), the connector will be cleaned up with the other
DRM objects in the call to drm_mode_config_cleanup(). However, since our
drm_connector is devm-allocated, by the time drm_mode_config_cleanup()
will be called, our connector will be long gone. Therefore, the
connector must be cleaned up when the bridge is detached to avoid
use-after-free conditions.

v2: Cleanup connector only if it was created

v3: Add FIXME

v4: (Use connector->dev) directly in if() block

The Linux kernel CVE team has assigned CVE-2021-47063 to this issue.

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

	Issue introduced in 4.13 with commit 13dfc0540a57 and fixed in 5.10.37 with commit ce450934a00c
	Issue introduced in 4.13 with commit 13dfc0540a57 and fixed in 5.11.21 with commit 18149b420c9b
	Issue introduced in 4.13 with commit 13dfc0540a57 and fixed in 5.12.4 with commit 98d7d76a74e4
	Issue introduced in 4.13 with commit 13dfc0540a57 and fixed in 5.13 with commit 4d906839d321

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-2021-47063
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/gpu/drm/bridge/panel.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/ce450934a00cf896e648fde08d0bd1426653d7a2
	https://git.kernel.org/stable/c/18149b420c9bd93c443e8d1f48a063d71d9f6aa1
	https://git.kernel.org/stable/c/98d7d76a74e48ec3ddf2e23950adff7edcab9327
	https://git.kernel.org/stable/c/4d906839d321c2efbf3fed4bc31ffd9ff55b75c0