Subject: CVE-2021-47025: iommu/mediatek: Always enable the clk on resume

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

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

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

iommu/mediatek: Always enable the clk on resume

In mtk_iommu_runtime_resume always enable the clk, even
if m4u_dom is null. Otherwise the 'suspend' cb might
disable the clk which is already disabled causing the warning:

[    1.586104] infra_m4u already disabled
[    1.586133] WARNING: CPU: 0 PID: 121 at drivers/clk/clk.c:952 clk_core_disable+0xb0/0xb8
[    1.594391] mtk-iommu 10205000.iommu: bound 18001000.larb (ops mtk_smi_larb_component_ops)
[    1.598108] Modules linked in:
[    1.598114] CPU: 0 PID: 121 Comm: kworker/0:2 Not tainted 5.12.0-rc5 #69
[    1.609246] mtk-iommu 10205000.iommu: bound 14027000.larb (ops mtk_smi_larb_component_ops)
[    1.617487] Hardware name: Google Elm (DT)
[    1.617491] Workqueue: pm pm_runtime_work
[    1.620545] mtk-iommu 10205000.iommu: bound 19001000.larb (ops mtk_smi_larb_component_ops)

[    1.627229] pstate: 60000085 (nZCv daIf -PAN -UAO -TCO BTYPE=--)
[    1.659297] pc : clk_core_disable+0xb0/0xb8
[    1.663475] lr : clk_core_disable+0xb0/0xb8
[    1.667652] sp : ffff800011b9bbe0
[    1.670959] x29: ffff800011b9bbe0 x28: 0000000000000000
[    1.676267] x27: ffff800011448000 x26: ffff8000100cfd98
[    1.681574] x25: ffff800011b9bd48 x24: 0000000000000000
[    1.686882] x23: 0000000000000000 x22: ffff8000106fad90
[    1.692189] x21: 000000000000000a x20: ffff0000c0048500
[    1.697496] x19: ffff0000c0048500 x18: ffffffffffffffff
[    1.702804] x17: 0000000000000000 x16: 0000000000000000
[    1.708112] x15: ffff800011460300 x14: fffffffffffe0000
[    1.713420] x13: ffff8000114602d8 x12: 0720072007200720
[    1.718727] x11: 0720072007200720 x10: 0720072007200720
[    1.724035] x9 : ffff800011b9bbe0 x8 : ffff800011b9bbe0
[    1.729342] x7 : 0000000000000009 x6 : ffff8000114b8328
[    1.734649] x5 : 0000000000000000 x4 : 0000000000000000
[    1.739956] x3 : 00000000ffffffff x2 : ffff800011460298
[    1.745263] x1 : 1af1d7de276f4500 x0 : 0000000000000000
[    1.750572] Call trace:
[    1.753010]  clk_core_disable+0xb0/0xb8
[    1.756840]  clk_core_disable_lock+0x24/0x40
[    1.761105]  clk_disable+0x20/0x30
[    1.764501]  mtk_iommu_runtime_suspend+0x88/0xa8
[    1.769114]  pm_generic_runtime_suspend+0x2c/0x48
[    1.773815]  __rpm_callback+0xe0/0x178
[    1.777559]  rpm_callback+0x24/0x88
[    1.781041]  rpm_suspend+0xdc/0x470
[    1.784523]  rpm_idle+0x12c/0x170
[    1.787831]  pm_runtime_work+0xa8/0xc0
[    1.791573]  process_one_work+0x1e8/0x360
[    1.795580]  worker_thread+0x44/0x478
[    1.799237]  kthread+0x150/0x158
[    1.802460]  ret_from_fork+0x10/0x30
[    1.806034] ---[ end trace 82402920ef64573b ]---
[    1.810728] ------------[ cut here ]------------

In addition, we now don't need to enable the clock from the
function mtk_iommu_hw_init since it is already enabled by the resume.

The Linux kernel CVE team has assigned CVE-2021-47025 to this issue.

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

	Issue introduced in 5.12 with commit c0b57581b73b and fixed in 5.12.4 with commit 5cad9e2caa96
	Issue introduced in 5.12 with commit c0b57581b73b and fixed in 5.13 with commit b34ea31fe013

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-2021-47025
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/iommu/mtk_iommu.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/5cad9e2caa9613fdcd246bd4ebf0ffbec1cba2ca
	https://git.kernel.org/stable/c/b34ea31fe013569d42b7e8681ef3f717f77c5b72