Subject: CVE-2024-38664: drm: zynqmp_dpsub: Always register bridge

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

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

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

drm: zynqmp_dpsub: Always register bridge

We must always register the DRM bridge, since zynqmp_dp_hpd_work_func
calls drm_bridge_hpd_notify, which in turn expects hpd_mutex to be
initialized. We do this before zynqmp_dpsub_drm_init since that calls
drm_bridge_attach. This fixes the following lockdep warning:

[   19.217084] ------------[ cut here ]------------
[   19.227530] DEBUG_LOCKS_WARN_ON(lock->magic != lock)
[   19.227768] WARNING: CPU: 0 PID: 140 at kernel/locking/mutex.c:582 __mutex_lock+0x4bc/0x550
[   19.241696] Modules linked in:
[   19.244937] CPU: 0 PID: 140 Comm: kworker/0:4 Not tainted 6.6.20+ #96
[   19.252046] Hardware name: xlnx,zynqmp (DT)
[   19.256421] Workqueue: events zynqmp_dp_hpd_work_func
[   19.261795] pstate: 60000005 (nZCv daif -PAN -UAO -TCO -DIT -SSBS BTYPE=--)
[   19.269104] pc : __mutex_lock+0x4bc/0x550
[   19.273364] lr : __mutex_lock+0x4bc/0x550
[   19.277592] sp : ffffffc085c5bbe0
[   19.281066] x29: ffffffc085c5bbe0 x28: 0000000000000000 x27: ffffff88009417f8
[   19.288624] x26: ffffff8800941788 x25: ffffff8800020008 x24: ffffffc082aa3000
[   19.296227] x23: ffffffc080d90e3c x22: 0000000000000002 x21: 0000000000000000
[   19.303744] x20: 0000000000000000 x19: ffffff88002f5210 x18: 0000000000000000
[   19.311295] x17: 6c707369642e3030 x16: 3030613464662072 x15: 0720072007200720
[   19.318922] x14: 0000000000000000 x13: 284e4f5f4e524157 x12: 0000000000000001
[   19.326442] x11: 0001ffc085c5b940 x10: 0001ff88003f388b x9 : 0001ff88003f3888
[   19.334003] x8 : 0001ff88003f3888 x7 : 0000000000000000 x6 : 0000000000000000
[   19.341537] x5 : 0000000000000000 x4 : 0000000000001668 x3 : 0000000000000000
[   19.349054] x2 : 0000000000000000 x1 : 0000000000000000 x0 : ffffff88003f3880
[   19.356581] Call trace:
[   19.359160]  __mutex_lock+0x4bc/0x550
[   19.363032]  mutex_lock_nested+0x24/0x30
[   19.367187]  drm_bridge_hpd_notify+0x2c/0x6c
[   19.371698]  zynqmp_dp_hpd_work_func+0x44/0x54
[   19.376364]  process_one_work+0x3ac/0x988
[   19.380660]  worker_thread+0x398/0x694
[   19.384736]  kthread+0x1bc/0x1c0
[   19.388241]  ret_from_fork+0x10/0x20
[   19.392031] irq event stamp: 183
[   19.395450] hardirqs last  enabled at (183): [<ffffffc0800b9278>] finish_task_switch.isra.0+0xa8/0x2d4
[   19.405140] hardirqs last disabled at (182): [<ffffffc081ad3754>] __schedule+0x714/0xd04
[   19.413612] softirqs last  enabled at (114): [<ffffffc080133de8>] srcu_invoke_callbacks+0x158/0x23c
[   19.423128] softirqs last disabled at (110): [<ffffffc080133de8>] srcu_invoke_callbacks+0x158/0x23c
[   19.432614] ---[ end trace 0000000000000000 ]---

(cherry picked from commit 61ba791c4a7a09a370c45b70a81b8c7d4cf6b2ae)

The Linux kernel CVE team has assigned CVE-2024-38664 to this issue.

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

	Issue introduced in 6.2 with commit eb2d64bfcc17 and fixed in 6.6.33 with commit 6ead3eccf67b
	Issue introduced in 6.2 with commit eb2d64bfcc17 and fixed in 6.9.4 with commit 603661357056
	Issue introduced in 6.2 with commit eb2d64bfcc17 and fixed in 6.10 with commit be3f3042391d

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-2024-38664
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/xlnx/zynqmp_dpsub.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/6ead3eccf67bc8318b1ce95ed879b2cc05b4fce9
	https://git.kernel.org/stable/c/603661357056b5e5ba6d86f505fbc936eff396ba
	https://git.kernel.org/stable/c/be3f3042391d061cfca2bd22630e0d101acea5fc