Subject: CVE-2022-48750: hwmon: (nct6775) Fix crash in clear_caseopen

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

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

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

hwmon: (nct6775) Fix crash in clear_caseopen

Paweł Marciniak reports the following crash, observed when clearing
the chassis intrusion alarm.

BUG: kernel NULL pointer dereference, address: 0000000000000028
PGD 0 P4D 0
Oops: 0000 [#1] PREEMPT SMP PTI
CPU: 3 PID: 4815 Comm: bash Tainted: G S                5.16.2-200.fc35.x86_64 #1
Hardware name: To Be Filled By O.E.M. To Be Filled By O.E.M./Z97 Extreme4, BIOS P2.60A 05/03/2018
RIP: 0010:clear_caseopen+0x5a/0x120 [nct6775]
Code: 68 70 e8 e9 32 b1 e3 85 c0 0f 85 d2 00 00 00 48 83 7c 24 ...
RSP: 0018:ffffabcb02803dd8 EFLAGS: 00010246
RAX: 0000000000000000 RBX: 0000000000000002 RCX: 0000000000000000
RDX: ffff8e8808192880 RSI: 0000000000000000 RDI: ffff8e87c7509a68
RBP: 0000000000000000 R08: 0000000000000001 R09: 000000000000000a
R10: 000000000000000a R11: f000000000000000 R12: 000000000000001f
R13: ffff8e87c7509828 R14: ffff8e87c7509a68 R15: ffff8e88494527a0
FS:  00007f4db9151740(0000) GS:ffff8e8ebfec0000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000000000000028 CR3: 0000000166b66001 CR4: 00000000001706e0
Call Trace:
 <TASK>
 kernfs_fop_write_iter+0x11c/0x1b0
 new_sync_write+0x10b/0x180
 vfs_write+0x209/0x2a0
 ksys_write+0x4f/0xc0
 do_syscall_64+0x3b/0x90
 entry_SYSCALL_64_after_hwframe+0x44/0xae

The problem is that the device passed to clear_caseopen() is the hwmon
device, not the platform device, and the platform data is not set in the
hwmon device. Store the pointer to sio_data in struct nct6775_data and
get if from there if needed.

The Linux kernel CVE team has assigned CVE-2022-48750 to this issue.

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

	Issue introduced in 5.16 with commit 2e7b9886968b and fixed in 5.16.5 with commit cfb7d12f2e4a
	Issue introduced in 5.16 with commit 2e7b9886968b and fixed in 5.17 with commit 79da533d3cc7

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-2022-48750
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/hwmon/nct6775.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/cfb7d12f2e4a4d694f49e9b4ebb352f7b67cdfbb
	https://git.kernel.org/stable/c/79da533d3cc717ccc05ddbd3190da8a72bc2408b