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

Official 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.

Affected packages & fixed versions

Affected products (as reported)

References

• 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