CVE-2026-98499: HID: wacom: fix OOB read in wacom_wac_pen_serial_enforce()

CVE-2026-98499: HID: wacom: fix OOB read in wacom_wac_pen_serial_enforce()

[Greg Kroah-Hartman]

From: Greg Kroah-Hartman <gregkh@kernel.org>

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

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

HID: wacom: fix OOB read in wacom_wac_pen_serial_enforce()

The 'wacom_wac_pen_serial_enforce()' function may calculate and pass an
invalid offset to hid_field_extract(), resulting in memory reads at
incorrect addresses -- possibly beyond the end of the report.  If a
field in the HID descriptor lists more usages than its Report Count
actually reserves space for, the function's inner 'j' will walk past
the end of the field:

	for (i = 0; i < report->maxfield; i++) {
		for (j = 0; j < report->field[i]->maxusage; j++) {
			...
			value = hid_field_extract(hdev, raw_data + 1,
						  offset + j * size, size);

A descriptor listing 12288 usages against Report Count 1 has the loop
extract the usage at index 12287 from bit offset 98296 -- about 12 KB
past a 2-byte received report.  The value is stored in
wacom_wac->serial[0] and can reach userspace as an MSC_SERIAL event,
making this an information disclosure.

Clamp the loop to field->report_count, the number of value slots the
report holds.  Value slots past the last declared usage are still
scanned; they reuse that usage (HID 1.11, 6.2.2.8).

Verified on v6.12.105 with a UHID reproducer: a 2-byte report from
such a descriptor trips KASAN before the patch and not after it.

The Linux kernel CVE team has assigned CVE-2026-98499 to this issue.


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

	Issue introduced in 4.16 with commit 83417206427bdf0fef9fa69957807194f25923c3 and fixed in 5.10.271 with commit 9aa62f967b6a4bb30aa3b778e02c8a5ca6bcde51
	Issue introduced in 4.16 with commit 83417206427bdf0fef9fa69957807194f25923c3 and fixed in 5.15.222 with commit 26471d954bbfbfb9032994f7f485802ee20e0582
	Issue introduced in 4.16 with commit 83417206427bdf0fef9fa69957807194f25923c3 and fixed in 6.1.189 with commit 456afe4707e23cc114ad833197f63b52bb8fd1e7
	Issue introduced in 4.16 with commit 83417206427bdf0fef9fa69957807194f25923c3 and fixed in 6.6.158 with commit 65e7c4b5366b770c60dfefac3f1d06e33a9e411e
	Issue introduced in 4.16 with commit 83417206427bdf0fef9fa69957807194f25923c3 and fixed in 6.12.112 with commit eaa7d29341ef4b91e84ad097562982288a7c376c
	Issue introduced in 4.16 with commit 83417206427bdf0fef9fa69957807194f25923c3 and fixed in 6.18.55 with commit c3129e6f26e18c0886ede7265f187a7ec289e1d1
	Issue introduced in 4.16 with commit 83417206427bdf0fef9fa69957807194f25923c3 and fixed in 7.2.9 with commit 4b09b7c84b8633cd041181616bd15bf5e73c164d
	Issue introduced in 4.16 with commit 83417206427bdf0fef9fa69957807194f25923c3 and fixed in 7.3-rc5 with commit 9aa237cf66495b2426ddde8532e9b08a0ed83aaa

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-2026-98499
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/hid/wacom_sys.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/9aa62f967b6a4bb30aa3b778e02c8a5ca6bcde51
	https://git.kernel.org/stable/c/26471d954bbfbfb9032994f7f485802ee20e0582
	https://git.kernel.org/stable/c/456afe4707e23cc114ad833197f63b52bb8fd1e7
	https://git.kernel.org/stable/c/65e7c4b5366b770c60dfefac3f1d06e33a9e411e
	https://git.kernel.org/stable/c/eaa7d29341ef4b91e84ad097562982288a7c376c
	https://git.kernel.org/stable/c/c3129e6f26e18c0886ede7265f187a7ec289e1d1
	https://git.kernel.org/stable/c/4b09b7c84b8633cd041181616bd15bf5e73c164d
	https://git.kernel.org/stable/c/9aa237cf66495b2426ddde8532e9b08a0ed83aaa