FKIE_CVE-2026-74463

Vulnerability from fkie_nvd - Published: 2026-08-15 13:17 - Updated: 2026-08-19 17:21
Severity
Summary
In the Linux kernel, the following vulnerability has been resolved: i2c: jz4780: Cache host clock rate at probe to prevent CCF prepare_lock deadlock Fix a severe AB/BA deadlock between the Common Clock Framework (CCF) and the I2C adapter lock, which triggers when an I2C-controlled clock generator client (like the Si5351) is registered or modified under the CCF. During an i2c client clock (generator) frequency change, the CCF acquires its global 'prepare_lock' mutex and the driver calls i2c_transfer() to update the client's chip registers, stalling for the adapter's I2C bus lock. Concurrently, an independent, parallel transfer on the same bus (e.g., a GPIO expander handling LEDs) can hold the I2C adapter lock. Inside this parallel transfer path, jz4780_i2c_set_speed() calls clk_get_rate() on the host controller's input clock to calculate bus timings. This call attempts to acquire the blocked CCF 'prepare_lock', creating a circular dependency that freezes the system. The jz4780 host controller clock itself is static and never changes at runtime. However, calling clk_get_rate() inside the active transfer path introduces an unnecessary dependency on the CCF internal locks. Eliminate this synchronous clk_get_rate() call from the active transfer path by caching the static host peripheral clock rate once - inside the private jz4780_i2c structure during jz4780_i2c_probe(). Update jz4780_i2c_set_speed() to use this cached value, safely decoupling active I2C transactions from the CCF internal locks without any risk of stale timings. Assisted-by web based Google AI (pinpointing the bug and writing the message).
References
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/14429dc1c756c35e106f01ff09cadccb82f5531d
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/19b783335d62e7a2367436a6e1f1b37da1878360
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/aa1944b52d6492c48bdd17046578aa0d953546e6
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/b6cb47e186abba85a3b08aa3023067ab82577286
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/cc111696ef420f6bb552b2526530067977f0b406
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/d99607c888f26e8a4e9fe9772860cef4aff86bb4
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/deffad5bb4f8b4f09e46252f24754ddc9960b244
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/f96a719d9f8a797105ec5cacf568ab128e33391f
Impacted products
Vendor Product Version
To clipboard 

{
  "affected": [
    {
      "affectedData": [
        {
          "defaultStatus": "unaffected",
          "product": "Linux",
          "programFiles": [
            "drivers/i2c/busses/i2c-jz4780.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "lessThan": "cc111696ef420f6bb552b2526530067977f0b406",
              "status": "affected",
              "version": "ba92222ed63a12d09120df9b92f56cc990abac19",
              "versionType": "git"
            },
            {
              "lessThan": "f96a719d9f8a797105ec5cacf568ab128e33391f",
              "status": "affected",
              "version": "ba92222ed63a12d09120df9b92f56cc990abac19",
              "versionType": "git"
            },
            {
              "lessThan": "deffad5bb4f8b4f09e46252f24754ddc9960b244",
              "status": "affected",
              "version": "ba92222ed63a12d09120df9b92f56cc990abac19",
              "versionType": "git"
            },
            {
              "lessThan": "14429dc1c756c35e106f01ff09cadccb82f5531d",
              "status": "affected",
              "version": "ba92222ed63a12d09120df9b92f56cc990abac19",
              "versionType": "git"
            },
            {
              "lessThan": "b6cb47e186abba85a3b08aa3023067ab82577286",
              "status": "affected",
              "version": "ba92222ed63a12d09120df9b92f56cc990abac19",
              "versionType": "git"
            },
            {
              "lessThan": "19b783335d62e7a2367436a6e1f1b37da1878360",
              "status": "affected",
              "version": "ba92222ed63a12d09120df9b92f56cc990abac19",
              "versionType": "git"
            },
            {
              "lessThan": "aa1944b52d6492c48bdd17046578aa0d953546e6",
              "status": "affected",
              "version": "ba92222ed63a12d09120df9b92f56cc990abac19",
              "versionType": "git"
            },
            {
              "lessThan": "d99607c888f26e8a4e9fe9772860cef4aff86bb4",
              "status": "affected",
              "version": "ba92222ed63a12d09120df9b92f56cc990abac19",
              "versionType": "git"
            }
          ]
        },
        {
          "defaultStatus": "affected",
          "product": "Linux",
          "programFiles": [
            "drivers/i2c/busses/i2c-jz4780.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "status": "affected",
              "version": "4.1"
            },
            {
              "lessThan": "4.1",
              "status": "unaffected",
              "version": "0",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "5.10.*",
              "status": "unaffected",
              "version": "5.10.265",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "5.15.*",
              "status": "unaffected",
              "version": "5.15.216",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.1.*",
              "status": "unaffected",
              "version": "6.1.183",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.6.*",
              "status": "unaffected",
              "version": "6.6.151",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.12.*",
              "status": "unaffected",
              "version": "6.12.103",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.18.*",
              "status": "unaffected",
              "version": "6.18.44",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "7.1.*",
              "status": "unaffected",
              "version": "7.1.8",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "*",
              "status": "unaffected",
              "version": "7.2",
              "versionType": "original_commit_for_fix"
            }
          ]
        }
      ],
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
    }
  ],
  "cveTags": [],
  "descriptions": [
    {
      "lang": "en",
      "value": "In the Linux kernel, the following vulnerability has been resolved:\n\ni2c: jz4780: Cache host clock rate at probe to prevent CCF prepare_lock deadlock\n\nFix a severe AB/BA deadlock between the Common Clock Framework (CCF)\nand the I2C adapter lock, which triggers when an I2C-controlled clock\ngenerator client (like the Si5351) is registered or modified under the CCF.\n\nDuring an i2c client clock (generator) frequency change, the CCF acquires its global\n\u0027prepare_lock\u0027 mutex and the driver calls i2c_transfer() to update the client\u0027s\nchip registers, stalling for the adapter\u0027s I2C bus lock.\n\nConcurrently, an independent, parallel transfer on the same bus (e.g., a GPIO\nexpander handling LEDs) can hold the I2C adapter lock. Inside this parallel\ntransfer path, jz4780_i2c_set_speed() calls clk_get_rate() on the host\ncontroller\u0027s input clock to calculate bus timings. This call attempts to acquire\nthe blocked CCF \u0027prepare_lock\u0027, creating a circular dependency that freezes\nthe system.\n\nThe jz4780 host controller clock itself is static and never changes at runtime.\n\nHowever, calling clk_get_rate() inside the active transfer path introduces\nan unnecessary dependency on the CCF internal locks.\n\nEliminate this synchronous clk_get_rate() call from the active transfer\npath by caching the static host peripheral clock rate once - inside the private\njz4780_i2c structure during jz4780_i2c_probe(). Update jz4780_i2c_set_speed()\nto use this cached value, safely decoupling active I2C transactions from the\nCCF internal locks without any risk of stale timings.\n\nAssisted-by web based Google AI (pinpointing the bug and writing the message)."
    }
  ],
  "id": "CVE-2026-74463",
  "lastModified": "2026-08-19T17:21:03.237",
  "metrics": {},
  "published": "2026-08-15T13:17:50.963",
  "references": [
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/14429dc1c756c35e106f01ff09cadccb82f5531d"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/19b783335d62e7a2367436a6e1f1b37da1878360"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/aa1944b52d6492c48bdd17046578aa0d953546e6"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/b6cb47e186abba85a3b08aa3023067ab82577286"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/cc111696ef420f6bb552b2526530067977f0b406"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/d99607c888f26e8a4e9fe9772860cef4aff86bb4"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/deffad5bb4f8b4f09e46252f24754ddc9960b244"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/f96a719d9f8a797105ec5cacf568ab128e33391f"
    }
  ],
  "sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
  "vulnStatus": "Received"
}



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