---
id: CVE-2026-98848
title: 'rtc: ac100: Assign .num before accessing .hws'
summary: |-
  In the Linux kernel, the following vulnerability has been resolved:

  rtc: ac100: Assign .num before accessing .hws

  Commit f316cdff8d67 ("clk: Annotate struct clk_hw_onecell_data with
  __counted_by") annotated the hws member of 'struct cl…
severity: none
vendor: Linux
product: Linux
affected:
  - >-
    Linux >= f316cdff8d677db9ad9c90acb44c4cd535b0ee27 <
    6bb55381daf1a1bed0657189a1396e7467712525
  - >-
    Linux >= f316cdff8d677db9ad9c90acb44c4cd535b0ee27 <
    160619b38707241e22569f9c983a4b3d0890996a
  - >-
    Linux >= f316cdff8d677db9ad9c90acb44c4cd535b0ee27 <
    ad1bf77039cba83373bf1eff3784655e3e3ed2ab
  - >-
    Linux >= f316cdff8d677db9ad9c90acb44c4cd535b0ee27 <
    6a4117eee82dd85f11bf898bf66026764011eeb6
  - Linux 6.6
published: '2026-10-18'
updated: '2026-10-18'
sourceUpdated: '2026-10-18T15:50:47.105Z'
source: CVEORG
sourceUrl: 'https://www.cve.org/CVERecord?id=CVE-2026-98848'
references:
  - url: 'https://git.kernel.org/stable/c/6bb55381daf1a1bed0657189a1396e7467712525'
  - url: 'https://git.kernel.org/stable/c/160619b38707241e22569f9c983a4b3d0890996a'
  - url: 'https://git.kernel.org/stable/c/ad1bf77039cba83373bf1eff3784655e3e3ed2ab'
  - url: 'https://git.kernel.org/stable/c/6a4117eee82dd85f11bf898bf66026764011eeb6'
tags:
  - cve.org
ingestedAt: '2026-10-18T16:47:32.464Z'
---

## Overview

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

rtc: ac100: Assign .num before accessing .hws

Commit f316cdff8d67 ("clk: Annotate struct clk_hw_onecell_data with
__counted_by") annotated the hws member of 'struct clk_hw_onecell_data'
with __counted_by, which informs the bounds sanitizer (UBSAN_BOUNDS)
about the number of elements in .hws[], so that it can warn when .hws[]
is accessed out of bounds. As noted in that change, the __counted_by
member must be initialized with the number of elements before the first
array access happens, otherwise there will be a warning from each access
prior to the initialization because the number of elements is zero.
This occurs in ac100_rtc_register_clks() due to .num being assigned only
after every clkout clock has been stored in .hws[]. With
CONFIG_UBSAN_BOUNDS and a compiler that implements __counted_by (GCC
15.1+ or Clang 20.1+), this triggers an array-index-out-of-bounds report
during probe, and with CONFIG_UBSAN_TRAP the first store traps.

Initialize .num with AC100_CLKOUT_NUM, the number of elements .hws[] was
allocated with, right after the allocation. That is the value the loop
counter ends up at on the success path anyway, so the provider's
behaviour is unchanged.

## Affected

- `Linux >= f316cdff8d677db9ad9c90acb44c4cd535b0ee27 < 6bb55381daf1a1bed0657189a1396e7467712525`
- `Linux >= f316cdff8d677db9ad9c90acb44c4cd535b0ee27 < 160619b38707241e22569f9c983a4b3d0890996a`
- `Linux >= f316cdff8d677db9ad9c90acb44c4cd535b0ee27 < ad1bf77039cba83373bf1eff3784655e3e3ed2ab`
- `Linux >= f316cdff8d677db9ad9c90acb44c4cd535b0ee27 < 6a4117eee82dd85f11bf898bf66026764011eeb6`
- `Linux 6.6`

## Remediation

Refer to the linked advisories for vendor-supplied fixes and affected version ranges.