hwmon: (occ) Fix division by zero in occ_show_power_1()

{
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  "url": "https://osv.dev/vulnerability/CVE-2026-31770",
  "method": "structured",
  "payload": {
    "kind": "advisory",
    "title": "hwmon: (occ) Fix division by zero in occ_show_power_1()",
    "summary": "In the Linux kernel, the following vulnerability has been resolved: hwmon: (occ) Fix division by zero in occ_show_power_1() In occ_show_power_1() case 1, the accumulator is divided by update_tag without checking for zero. If no samples have been collected yet (e.g. during early boot when the sensor block is included but hasn't been updated), update_tag is zero, causing a kernel divide-by-zero crash. The 2019 fix in commit 211186cae14d (\"hwmon: (occ) Fix division by zero issue\") only addressed occ_get_powr_avg() used by occ_show_power_2() and occ_show_power_a0(). This separate code path in occ_show_power_1() was missed. Fix this by reusing the existing occ_get_powr_avg() helper, which already handles the zero-sample case and uses mul_u64_u32_div() to multiply before dividing for better precision. Move the helper above occ_show_power_1() so it is visible at the call site. [groeck: Fix alignment problems reported by checkpatch]",
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      "modified": "2026-10-28T02:30:22.801139244Z",
      "provider": "osv",
      "references": [
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        "https://git.kernel.org/stable/c/2502684b9e835de9a992ec47c3e6c6faabe3858d",
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        "https://git.kernel.org/stable/c/39e2a5bf970402a8530a319cf06122e216ba57b8",
        "https://git.kernel.org/stable/c/53e6175756b8c474b6247bbcea0aad3d68357475",
        "https://git.kernel.org/stable/c/7b89ce0c98bf3015f493ca4285b2d1056cd8c733",
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        "https://git.kernel.org/stable/c/c7d3712362c8ab8f82f441b649d9e446e7b9aa9d",
        "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/31xxx/CVE-2026-31770.json",
        "https://nvd.nist.gov/vuln/detail/CVE-2026-31770",
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  "source_id": "core-osv",
  "document_id": 488893,
  "published_at": "2026-05-01T14:14:59.256+00:00"
}