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GHSA-CFCM-PXWX-HG62

Vulnerability from github – Published: 2026-07-20 18:32 – Updated: 2026-07-20 18:32

Details

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

i2c: i801: fix hardware state machine corruption in error path

A severe livelock and subsequent Hung Task panic were observed in the i2c-i801 driver during concurrent Fuzzing. The crash is caused by an unconditional hardware register cleanup in the error handling path of i801_access().

When i801_check_pre() fails (e.g., returning -EBUSY because the SMBus controller is actively used by BIOS/ACPI), the kernel does not actually acquire the hardware ownership. However, the code jumps to the 'out' label and executes:

iowrite8(SMBHSTSTS_INUSE_STS | STATUS_FLAGS, SMBHSTSTS(priv));

This forcefully clears the INUSE_STS lock and resets the hardware status flags without owning the controller. Doing so interrupts ongoing BIOS/ACPI transactions and totally corrupts the SMBus hardware state machine.

Consequently, all subsequent i801_access() calls fail at the pre-check stage, triggering an endless stream of "SMBus is busy, can't use it!" error logs. Over a slow serial console, this printk flood monopolizes the CPU (Console Livelock), starving other processes trying to acquire the mmap_lock down_read semaphore, ultimately triggering the hung task watchdog.

Fix this by moving the 'out' label below the hardware register cleanup. If i801_check_pre() fails, we safely bypass the iowrite8() and only release the software locks (pm_runtime and mutex), strictly adhering to the rule of not releasing resources that were never acquired.

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{
  "affected": [],
  "aliases": [
    "CVE-2026-64205"
  ],
  "database_specific": {
    "cwe_ids": [],
    "github_reviewed": false,
    "github_reviewed_at": null,
    "nvd_published_at": "2026-07-20T17:18:22Z",
    "severity": null
  },
  "details": "In the Linux kernel, the following vulnerability has been resolved:\n\ni2c: i801: fix hardware state machine corruption in error path\n\nA severe livelock and subsequent Hung Task panic were observed in the\ni2c-i801 driver during concurrent Fuzzing. The crash is caused by an\nunconditional hardware register cleanup in the error handling path of\ni801_access().\n\nWhen i801_check_pre() fails (e.g., returning -EBUSY because the SMBus\ncontroller is actively used by BIOS/ACPI), the kernel does not actually\nacquire the hardware ownership. However, the code jumps to the \u0027out\u0027\nlabel and executes:\n\n    iowrite8(SMBHSTSTS_INUSE_STS | STATUS_FLAGS, SMBHSTSTS(priv));\n\nThis forcefully clears the INUSE_STS lock and resets the hardware status\nflags without owning the controller. Doing so interrupts ongoing BIOS/ACPI\ntransactions and totally corrupts the SMBus hardware state machine.\n\nConsequently, all subsequent i801_access() calls fail at the pre-check\nstage, triggering an endless stream of \"SMBus is busy, can\u0027t use it!\"\nerror logs. Over a slow serial console, this printk flood monopolizes\nthe CPU (Console Livelock), starving other processes trying to acquire\nthe mmap_lock down_read semaphore, ultimately triggering the hung task\nwatchdog.\n\nFix this by moving the \u0027out\u0027 label below the hardware register cleanup.\nIf i801_check_pre() fails, we safely bypass the iowrite8() and only\nrelease the software locks (pm_runtime and mutex), strictly adhering to\nthe rule of not releasing resources that were never acquired.",
  "id": "GHSA-cfcm-pxwx-hg62",
  "modified": "2026-07-20T18:32:33Z",
  "published": "2026-07-20T18:32:33Z",
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-64205"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/00904687b9c5527d569d9a1ca72119823e735a61"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/10dd1a736d557e310a77117832874729a0175d57"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/bb5133a7d5f3fe5c387770e25f2e00e682ce11ed"
    }
  ],
  "schema_version": "1.4.0",
  "severity": []
}

CVE-2026-64205 (GCVE-0-2026-64205)

Vulnerability from cvelistv5 – Published: 2026-07-20 16:27 – Updated: 2026-07-20 16:27

Title

i2c: i801: fix hardware state machine corruption in error path

Summary

In the Linux kernel, the following vulnerability has been resolved: i2c: i801: fix hardware state machine corruption in error path A severe livelock and subsequent Hung Task panic were observed in the i2c-i801 driver during concurrent Fuzzing. The crash is caused by an unconditional hardware register cleanup in the error handling path of i801_access(). When i801_check_pre() fails (e.g., returning -EBUSY because the SMBus controller is actively used by BIOS/ACPI), the kernel does not actually acquire the hardware ownership. However, the code jumps to the 'out' label and executes: iowrite8(SMBHSTSTS_INUSE_STS | STATUS_FLAGS, SMBHSTSTS(priv)); This forcefully clears the INUSE_STS lock and resets the hardware status flags without owning the controller. Doing so interrupts ongoing BIOS/ACPI transactions and totally corrupts the SMBus hardware state machine. Consequently, all subsequent i801_access() calls fail at the pre-check stage, triggering an endless stream of "SMBus is busy, can't use it!" error logs. Over a slow serial console, this printk flood monopolizes the CPU (Console Livelock), starving other processes trying to acquire the mmap_lock down_read semaphore, ultimately triggering the hung task watchdog. Fix this by moving the 'out' label below the hardware register cleanup. If i801_check_pre() fails, we safely bypass the iowrite8() and only release the software locks (pm_runtime and mutex), strictly adhering to the rule of not releasing resources that were never acquired.

Severity

No CVSS data available.

Assigner

Linux

References

3 references

URL	Tags
https://git.kernel.org/stable/c/bb5133a7d5f3fe5c3…
https://git.kernel.org/stable/c/00904687b9c5527d5…
https://git.kernel.org/stable/c/10dd1a736d557e310…

Impacted products

2 products

Vendor	Product	Version
Linux	Linux	Affected: 1f760b87e54cf56a25ab68f8dc625e339f6e46d5 , < bb5133a7d5f3fe5c387770e25f2e00e682ce11ed (git) Affected: 1f760b87e54cf56a25ab68f8dc625e339f6e46d5 , < 00904687b9c5527d569d9a1ca72119823e735a61 (git) Affected: 1f760b87e54cf56a25ab68f8dc625e339f6e46d5 , < 10dd1a736d557e310a77117832874729a0175d57 (git)
Linux	Linux	Affected: 6.3 Unaffected: 0 , < 6.3 (semver) Unaffected: 6.18.39 , ≤ 6.18.* (semver) Unaffected: 7.1.4 , ≤ 7.1.* (semver) Unaffected: 7.2-rc1 , ≤ * (original_commit_for_fix)

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{
  "containers": {
    "cna": {
      "affected": [
        {
          "defaultStatus": "unaffected",
          "product": "Linux",
          "programFiles": [
            "drivers/i2c/busses/i2c-i801.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "lessThan": "bb5133a7d5f3fe5c387770e25f2e00e682ce11ed",
              "status": "affected",
              "version": "1f760b87e54cf56a25ab68f8dc625e339f6e46d5",
              "versionType": "git"
            },
            {
              "lessThan": "00904687b9c5527d569d9a1ca72119823e735a61",
              "status": "affected",
              "version": "1f760b87e54cf56a25ab68f8dc625e339f6e46d5",
              "versionType": "git"
            },
            {
              "lessThan": "10dd1a736d557e310a77117832874729a0175d57",
              "status": "affected",
              "version": "1f760b87e54cf56a25ab68f8dc625e339f6e46d5",
              "versionType": "git"
            }
          ]
        },
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          "defaultStatus": "affected",
          "product": "Linux",
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          "vendor": "Linux",
          "versions": [
            {
              "status": "affected",
              "version": "6.3"
            },
            {
              "lessThan": "6.3",
              "status": "unaffected",
              "version": "0",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.18.*",
              "status": "unaffected",
              "version": "6.18.39",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "7.1.*",
              "status": "unaffected",
              "version": "7.1.4",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "*",
              "status": "unaffected",
              "version": "7.2-rc1",
              "versionType": "original_commit_for_fix"
            }
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        }
      ],
      "cpeApplicability": [
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          "nodes": [
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                },
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                  "versionStartIncluding": "6.3",
                  "vulnerable": true
                }
              ],
              "negate": false,
              "operator": "OR"
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          ]
        }
      ],
      "descriptions": [
        {
          "lang": "en",
          "value": "In the Linux kernel, the following vulnerability has been resolved:\n\ni2c: i801: fix hardware state machine corruption in error path\n\nA severe livelock and subsequent Hung Task panic were observed in the\ni2c-i801 driver during concurrent Fuzzing. The crash is caused by an\nunconditional hardware register cleanup in the error handling path of\ni801_access().\n\nWhen i801_check_pre() fails (e.g., returning -EBUSY because the SMBus\ncontroller is actively used by BIOS/ACPI), the kernel does not actually\nacquire the hardware ownership. However, the code jumps to the \u0027out\u0027\nlabel and executes:\n\n    iowrite8(SMBHSTSTS_INUSE_STS | STATUS_FLAGS, SMBHSTSTS(priv));\n\nThis forcefully clears the INUSE_STS lock and resets the hardware status\nflags without owning the controller. Doing so interrupts ongoing BIOS/ACPI\ntransactions and totally corrupts the SMBus hardware state machine.\n\nConsequently, all subsequent i801_access() calls fail at the pre-check\nstage, triggering an endless stream of \"SMBus is busy, can\u0027t use it!\"\nerror logs. Over a slow serial console, this printk flood monopolizes\nthe CPU (Console Livelock), starving other processes trying to acquire\nthe mmap_lock down_read semaphore, ultimately triggering the hung task\nwatchdog.\n\nFix this by moving the \u0027out\u0027 label below the hardware register cleanup.\nIf i801_check_pre() fails, we safely bypass the iowrite8() and only\nrelease the software locks (pm_runtime and mutex), strictly adhering to\nthe rule of not releasing resources that were never acquired."
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-07-20T16:27:53.310Z",
        "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "shortName": "Linux"
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        },
        {
          "url": "https://git.kernel.org/stable/c/10dd1a736d557e310a77117832874729a0175d57"
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      "title": "i2c: i801: fix hardware state machine corruption in error path",
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    "datePublished": "2026-07-20T16:27:53.310Z",
    "dateReserved": "2026-07-19T15:36:31.769Z",
    "dateUpdated": "2026-07-20T16:27:53.310Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2"
}

Sightings

Author	Source	Type	Date	Other

Nomenclature

Seen: The vulnerability was mentioned, discussed, or observed by the user.
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.

Detection rules are retrieved from Rulezet.

The MITRE ATT&CK techniques below are AI-generated suggestions, inferred from the description of the vulnerability by the CIRCL/vulnerability-attack-technique-classification-roberta-base model, served locally by ML-Gateway. They have not been verified by an analyst and are provided for guidance only.

Action not permitted

GHSA-CFCM-PXWX-HG62

CVE-2026-64205 (GCVE-0-2026-64205)

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Sightings

Nomenclature