Subject: CVE-2022-48826: drm/vc4: Fix deadlock on DSI device attach error

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

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

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

drm/vc4: Fix deadlock on DSI device attach error

DSI device attach to DSI host will be done with host device's lock
held.

Un-registering host in "device attach" error path (ex: probe retry)
will result in deadlock with below call trace and non operational
DSI display.

Startup Call trace:
[   35.043036]  rt_mutex_slowlock.constprop.21+0x184/0x1b8
[   35.043048]  mutex_lock_nested+0x7c/0xc8
[   35.043060]  device_del+0x4c/0x3e8
[   35.043075]  device_unregister+0x20/0x40
[   35.043082]  mipi_dsi_remove_device_fn+0x18/0x28
[   35.043093]  device_for_each_child+0x68/0xb0
[   35.043105]  mipi_dsi_host_unregister+0x40/0x90
[   35.043115]  vc4_dsi_host_attach+0xf0/0x120 [vc4]
[   35.043199]  mipi_dsi_attach+0x30/0x48
[   35.043209]  tc358762_probe+0x128/0x164 [tc358762]
[   35.043225]  mipi_dsi_drv_probe+0x28/0x38
[   35.043234]  really_probe+0xc0/0x318
[   35.043244]  __driver_probe_device+0x80/0xe8
[   35.043254]  driver_probe_device+0xb8/0x118
[   35.043263]  __device_attach_driver+0x98/0xe8
[   35.043273]  bus_for_each_drv+0x84/0xd8
[   35.043281]  __device_attach+0xf0/0x150
[   35.043290]  device_initial_probe+0x1c/0x28
[   35.043300]  bus_probe_device+0xa4/0xb0
[   35.043308]  deferred_probe_work_func+0xa0/0xe0
[   35.043318]  process_one_work+0x254/0x700
[   35.043330]  worker_thread+0x4c/0x448
[   35.043339]  kthread+0x19c/0x1a8
[   35.043348]  ret_from_fork+0x10/0x20

Shutdown Call trace:
[  365.565417] Call trace:
[  365.565423]  __switch_to+0x148/0x200
[  365.565452]  __schedule+0x340/0x9c8
[  365.565467]  schedule+0x48/0x110
[  365.565479]  schedule_timeout+0x3b0/0x448
[  365.565496]  wait_for_completion+0xac/0x138
[  365.565509]  __flush_work+0x218/0x4e0
[  365.565523]  flush_work+0x1c/0x28
[  365.565536]  wait_for_device_probe+0x68/0x158
[  365.565550]  device_shutdown+0x24/0x348
[  365.565561]  kernel_restart_prepare+0x40/0x50
[  365.565578]  kernel_restart+0x20/0x70
[  365.565591]  __do_sys_reboot+0x10c/0x220
[  365.565605]  __arm64_sys_reboot+0x2c/0x38
[  365.565619]  invoke_syscall+0x4c/0x110
[  365.565634]  el0_svc_common.constprop.3+0xfc/0x120
[  365.565648]  do_el0_svc+0x2c/0x90
[  365.565661]  el0_svc+0x4c/0xf0
[  365.565671]  el0t_64_sync_handler+0x90/0xb8
[  365.565682]  el0t_64_sync+0x180/0x184

The Linux kernel CVE team has assigned CVE-2022-48826 to this issue.

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

	Fixed in 5.15.24 with commit 770d1ba9a820
	Fixed in 5.16.10 with commit dddd832f3509
	Fixed in 5.17 with commit 0a3d12ab5097

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-2022-48826
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/vc4/vc4_dsi.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/770d1ba9a8201ce9bee0946eb03746449b6f3b80
	https://git.kernel.org/stable/c/dddd832f35096fbc5004e3a7e58fb4d2cefb8deb
	https://git.kernel.org/stable/c/0a3d12ab5097b1d045e693412e6b366b7e82031b