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GHSA-WGHV-7VWX-FC47

Vulnerability from github – Published: 2026-10-23 15:31 – Updated: 2026-10-23 15:31

Details

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

drm/xe: harden adjust_idledly() against divide-by-zero and overflow

adjust_idledly() has several corner-case issues flagged during review:

If xe_gt_clock_init() failed to recognise the crystal clock, gt->info.timestamp_base is 0, which makes idledly_units_ps also 0. The subsequent DIV_ROUND_CLOSEST(..., idledly_units_ps) is then a divide-by-zero and panics the kernel.
The tick-to-ns conversions are done in u32: idledly * idledly_units_ps, (maxcnt - 1) * 1000 Both overflow u32 before DIV_ROUND_CLOSEST() sees them.
If IDLE_WAIT_TIME reads back as 0, maxcnt evaluates to 0 and the maxcnt - 1 clamp wraps to 0xFFFFFFFF in u32.
The register only stores whole ticks, so the clamped ns value has to be converted to ticks and back. DIV_ROUND_CLOSEST() can round that conversion up past maxcnt:

maxcnt = 640 ns, one tick = 666664 ps

clamp: maxcnt - 1 = 639 ns ns -> ticks: 639000 / 666664 = 0.958 -> rounds to 1 tick tick -> ns: 1 * 666664 / 1000 = 667 ns

667 ns is programmed into RING_IDLEDLY, but 667 >= maxcnt (640), so xe_gt_WARN_ON() fires again on every subsequent init.

Return early if timestamp_base is 0 (the unknown-crystal path). Do the conversions in u64 via the *_ULL() helpers so they cannot wrap. Clamp with a floor (DIV_ROUND_DOWN_ULL) so the programmed delay stays strictly below maxcnt, and guard the maxcnt == 0 case with a zero delay while still writing RING_IDLEDLY so INHIBIT_SWITCH_UNTIL_PREEMPTED is cleared.

v2: Drop the redundant warn on the timestamp_base == 0 path; xe_gt_clock_init() already warns on an unrecognised crystal clock. Keep the early return to avoid the divide-by-zero. - Vinay

v3: Field-mask the RING_IDLEDLY write with REG_FIELD_PREP(IDLE_DELAY, ...) instead of writing the raw tick count, which could clobber INHIBIT_SWITCH_UNTIL_PREEMPTED and reserved bits. Split the inhibit-switch clear from the maxcnt clamp so a set inhibit bit no longer forces a needless delay overwrite when the delay itself is already valid. Use gt_to_xe(gt) instead of gt_to_xe(hwe->gt).

(cherry picked from commit d864065ea25e9d12897c175de9176ce46677e176)

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{
  "affected": [],
  "aliases": [
    "CVE-2026-98919"
  ],
  "database_specific": {
    "cwe_ids": [],
    "github_reviewed": false,
    "github_reviewed_at": null,
    "nvd_published_at": "2026-10-23T13:17:12Z",
    "severity": null
  },
  "details": "In the Linux kernel, the following vulnerability has been resolved:\n\ndrm/xe: harden adjust_idledly() against divide-by-zero and overflow\n\nadjust_idledly() has several corner-case issues flagged during review:\n\n  1. If xe_gt_clock_init() failed to recognise the crystal clock,\n     gt-\u003einfo.timestamp_base is 0, which makes idledly_units_ps also 0.\n     The subsequent DIV_ROUND_CLOSEST(..., idledly_units_ps) is then a\n     divide-by-zero and panics the kernel.\n\n  2. The tick-to-ns conversions are done in u32:\n        idledly * idledly_units_ps, (maxcnt - 1) * 1000\n     Both overflow u32 before DIV_ROUND_CLOSEST() sees them.\n\n  3. If IDLE_WAIT_TIME reads back as 0, maxcnt evaluates to 0 and\n     the maxcnt - 1 clamp wraps to 0xFFFFFFFF in u32.\n\n  4. The register only stores whole ticks, so the clamped ns value has\n     to be converted to ticks and back. DIV_ROUND_CLOSEST() can round\n     that conversion up past maxcnt:\n\n       maxcnt = 640 ns, one tick = 666664 ps\n\n       clamp:        maxcnt - 1        = 639 ns\n       ns -\u003e ticks:  639000 / 666664   = 0.958 -\u003e rounds to 1 tick\n       tick -\u003e ns:    1 * 666664 / 1000 = 667 ns\n\n     667 ns is programmed into RING_IDLEDLY, but 667 \u003e= maxcnt (640),\n     so xe_gt_WARN_ON() fires again on every subsequent init.\n\nReturn early if timestamp_base is 0 (the unknown-crystal path).\nDo the conversions in u64 via the *_ULL() helpers so they cannot wrap.\nClamp with a floor (DIV_ROUND_DOWN_ULL) so the programmed delay stays\nstrictly below maxcnt, and guard the maxcnt == 0 case with a zero delay\nwhile still writing RING_IDLEDLY so INHIBIT_SWITCH_UNTIL_PREEMPTED is\ncleared.\n\nv2: Drop the redundant warn on the timestamp_base == 0 path;\n    xe_gt_clock_init() already warns on an unrecognised crystal clock.\n    Keep the early return to avoid the divide-by-zero. - Vinay\n\nv3: Field-mask the RING_IDLEDLY write with REG_FIELD_PREP(IDLE_DELAY, ...)\n    instead of writing the raw tick count, which could clobber\n    INHIBIT_SWITCH_UNTIL_PREEMPTED and reserved bits. Split the\n    inhibit-switch clear from the maxcnt clamp so a set inhibit bit no\n    longer forces a needless delay overwrite when the delay itself is\n    already valid. Use gt_to_xe(gt) instead of gt_to_xe(hwe-\u003egt).\n\n(cherry picked from commit d864065ea25e9d12897c175de9176ce46677e176)",
  "id": "GHSA-wghv-7vwx-fc47",
  "modified": "2026-10-23T15:31:30Z",
  "published": "2026-10-23T15:31:30Z",
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-98919"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/2bcbfc5e7bfa9cc76818c54db698da5bdc13d9ff"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/531d4cd03118224022dc21ae25af052ce2a9e267"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/90f467577ebc28c5bc4ba2f0f1b83a4419fb0740"
    }
  ],
  "schema_version": "1.4.0",
  "severity": []
}

CVE-2026-98919 (GCVE-0-2026-98919)

Vulnerability from cvelistv5 – Published: 2026-10-23 12:01 – Updated: 2026-10-23 12:05

Title

drm/xe: harden adjust_idledly() against divide-by-zero and overflow

Summary

In the Linux kernel, the following vulnerability has been resolved: drm/xe: harden adjust_idledly() against divide-by-zero and overflow adjust_idledly() has several corner-case issues flagged during review: 1. If xe_gt_clock_init() failed to recognise the crystal clock, gt->info.timestamp_base is 0, which makes idledly_units_ps also 0. The subsequent DIV_ROUND_CLOSEST(..., idledly_units_ps) is then a divide-by-zero and panics the kernel. 2. The tick-to-ns conversions are done in u32: idledly * idledly_units_ps, (maxcnt - 1) * 1000 Both overflow u32 before DIV_ROUND_CLOSEST() sees them. 3. If IDLE_WAIT_TIME reads back as 0, maxcnt evaluates to 0 and the maxcnt - 1 clamp wraps to 0xFFFFFFFF in u32. 4. The register only stores whole ticks, so the clamped ns value has to be converted to ticks and back. DIV_ROUND_CLOSEST() can round that conversion up past maxcnt: maxcnt = 640 ns, one tick = 666664 ps clamp: maxcnt - 1 = 639 ns ns -> ticks: 639000 / 666664 = 0.958 -> rounds to 1 tick tick -> ns: 1 * 666664 / 1000 = 667 ns 667 ns is programmed into RING_IDLEDLY, but 667 >= maxcnt (640), so xe_gt_WARN_ON() fires again on every subsequent init. Return early if timestamp_base is 0 (the unknown-crystal path). Do the conversions in u64 via the *_ULL() helpers so they cannot wrap. Clamp with a floor (DIV_ROUND_DOWN_ULL) so the programmed delay stays strictly below maxcnt, and guard the maxcnt == 0 case with a zero delay while still writing RING_IDLEDLY so INHIBIT_SWITCH_UNTIL_PREEMPTED is cleared. v2: Drop the redundant warn on the timestamp_base == 0 path; xe_gt_clock_init() already warns on an unrecognised crystal clock. Keep the early return to avoid the divide-by-zero. - Vinay v3: Field-mask the RING_IDLEDLY write with REG_FIELD_PREP(IDLE_DELAY, ...) instead of writing the raw tick count, which could clobber INHIBIT_SWITCH_UNTIL_PREEMPTED and reserved bits. Split the inhibit-switch clear from the maxcnt clamp so a set inhibit bit no longer forces a needless delay overwrite when the delay itself is already valid. Use gt_to_xe(gt) instead of gt_to_xe(hwe->gt). (cherry picked from commit d864065ea25e9d12897c175de9176ce46677e176)

Severity

No CVSS data available.

Assigner

Linux CNA under the mitre root

CNA scorecard D 53/100 over 7061 records in the last 180 days details

References

3 references

URL	Tags
https://git.kernel.org/stable/c/2bcbfc5e7bfa9cc76…
https://git.kernel.org/stable/c/531d4cd0311822402…
https://git.kernel.org/stable/c/90f467577ebc28c5b…

Impacted products

2 products

Vendor	Product	Version
Linux	Linux	Affected: d2de4410a88ffc6053300d03041cc73b8c85dbaf , < 2bcbfc5e7bfa9cc76818c54db698da5bdc13d9ff (git) Affected: d2de4410a88ffc6053300d03041cc73b8c85dbaf , < 531d4cd03118224022dc21ae25af052ce2a9e267 (git) Affected: d2de4410a88ffc6053300d03041cc73b8c85dbaf , < 90f467577ebc28c5bc4ba2f0f1b83a4419fb0740 (git)
Linux	Linux	Affected: 6.15 Unaffected: 0 , < 6.15 (semver) Unaffected: 6.18.55 , ≤ 6.18.* (semver) Unaffected: 7.2.9 , ≤ 7.2.* (semver) Unaffected: 7.3 , ≤ * (original_commit_for_fix)

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{
  "containers": {
    "cna": {
      "affected": [
        {
          "defaultStatus": "unaffected",
          "product": "Linux",
          "programFiles": [
            "drivers/gpu/drm/xe/xe_hw_engine.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "lessThan": "2bcbfc5e7bfa9cc76818c54db698da5bdc13d9ff",
              "status": "affected",
              "version": "d2de4410a88ffc6053300d03041cc73b8c85dbaf",
              "versionType": "git"
            },
            {
              "lessThan": "531d4cd03118224022dc21ae25af052ce2a9e267",
              "status": "affected",
              "version": "d2de4410a88ffc6053300d03041cc73b8c85dbaf",
              "versionType": "git"
            },
            {
              "lessThan": "90f467577ebc28c5bc4ba2f0f1b83a4419fb0740",
              "status": "affected",
              "version": "d2de4410a88ffc6053300d03041cc73b8c85dbaf",
              "versionType": "git"
            }
          ]
        },
        {
          "defaultStatus": "affected",
          "product": "Linux",
          "programFiles": [
            "drivers/gpu/drm/xe/xe_hw_engine.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "status": "affected",
              "version": "6.15"
            },
            {
              "lessThan": "6.15",
              "status": "unaffected",
              "version": "0",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.18.*",
              "status": "unaffected",
              "version": "6.18.55",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "7.2.*",
              "status": "unaffected",
              "version": "7.2.9",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "*",
              "status": "unaffected",
              "version": "7.3",
              "versionType": "original_commit_for_fix"
            }
          ]
        }
      ],
      "cpeApplicability": [
        {
          "nodes": [
            {
              "cpeMatch": [
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "6.18.55",
                  "versionStartIncluding": "6.15",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "7.2.9",
                  "versionStartIncluding": "6.15",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "7.3",
                  "versionStartIncluding": "6.15",
                  "vulnerable": true
                }
              ],
              "negate": false,
              "operator": "OR"
            }
          ]
        }
      ],
      "descriptions": [
        {
          "lang": "en",
          "value": "In the Linux kernel, the following vulnerability has been resolved:\n\ndrm/xe: harden adjust_idledly() against divide-by-zero and overflow\n\nadjust_idledly() has several corner-case issues flagged during review:\n\n  1. If xe_gt_clock_init() failed to recognise the crystal clock,\n     gt-\u003einfo.timestamp_base is 0, which makes idledly_units_ps also 0.\n     The subsequent DIV_ROUND_CLOSEST(..., idledly_units_ps) is then a\n     divide-by-zero and panics the kernel.\n\n  2. The tick-to-ns conversions are done in u32:\n        idledly * idledly_units_ps, (maxcnt - 1) * 1000\n     Both overflow u32 before DIV_ROUND_CLOSEST() sees them.\n\n  3. If IDLE_WAIT_TIME reads back as 0, maxcnt evaluates to 0 and\n     the maxcnt - 1 clamp wraps to 0xFFFFFFFF in u32.\n\n  4. The register only stores whole ticks, so the clamped ns value has\n     to be converted to ticks and back. DIV_ROUND_CLOSEST() can round\n     that conversion up past maxcnt:\n\n       maxcnt = 640 ns, one tick = 666664 ps\n\n       clamp:        maxcnt - 1        = 639 ns\n       ns -\u003e ticks:  639000 / 666664   = 0.958 -\u003e rounds to 1 tick\n       tick -\u003e ns:    1 * 666664 / 1000 = 667 ns\n\n     667 ns is programmed into RING_IDLEDLY, but 667 \u003e= maxcnt (640),\n     so xe_gt_WARN_ON() fires again on every subsequent init.\n\nReturn early if timestamp_base is 0 (the unknown-crystal path).\nDo the conversions in u64 via the *_ULL() helpers so they cannot wrap.\nClamp with a floor (DIV_ROUND_DOWN_ULL) so the programmed delay stays\nstrictly below maxcnt, and guard the maxcnt == 0 case with a zero delay\nwhile still writing RING_IDLEDLY so INHIBIT_SWITCH_UNTIL_PREEMPTED is\ncleared.\n\nv2: Drop the redundant warn on the timestamp_base == 0 path;\n    xe_gt_clock_init() already warns on an unrecognised crystal clock.\n    Keep the early return to avoid the divide-by-zero. - Vinay\n\nv3: Field-mask the RING_IDLEDLY write with REG_FIELD_PREP(IDLE_DELAY, ...)\n    instead of writing the raw tick count, which could clobber\n    INHIBIT_SWITCH_UNTIL_PREEMPTED and reserved bits. Split the\n    inhibit-switch clear from the maxcnt clamp so a set inhibit bit no\n    longer forces a needless delay overwrite when the delay itself is\n    already valid. Use gt_to_xe(gt) instead of gt_to_xe(hwe-\u003egt).\n\n(cherry picked from commit d864065ea25e9d12897c175de9176ce46677e176)"
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-10-23T12:05:08.723Z",
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        "shortName": "Linux"
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          "url": "https://git.kernel.org/stable/c/531d4cd03118224022dc21ae25af052ce2a9e267"
        },
        {
          "url": "https://git.kernel.org/stable/c/90f467577ebc28c5bc4ba2f0f1b83a4419fb0740"
        }
      ],
      "title": "drm/xe: harden adjust_idledly() against divide-by-zero and overflow",
      "x_generator": {
        "engine": "bippy-1.2.0"
      }
    }
  },
  "cveMetadata": {
    "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
    "assignerShortName": "Linux",
    "cveId": "CVE-2026-98919",
    "datePublished": "2026-10-23T12:01:55.092Z",
    "dateReserved": "2026-09-25T10:25:14.380Z",
    "dateUpdated": "2026-10-23T12:05:08.723Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2"
}

Sightings

Author	Source	Type	Date	Other

Nomenclature

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Confirmed: The vulnerability has been validated from an analyst's perspective.
Published Proof of Concept: A public proof of concept is available for this vulnerability.
Exploited: The vulnerability was observed as exploited by the user who reported the sighting.
Patched: The vulnerability was observed as successfully patched by the user who reported the sighting.
Not exploited: The vulnerability was not observed as exploited by the user who reported the sighting.
Not confirmed: The user expressed doubt about the validity of the vulnerability.
Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.

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