{
  "schema_version": "1.6.1",
  "id": "RPI-CVE-2026-74463",
  "modified": "2026-10-07T17:22:01Z",
  "upstream": [
    "CVE-2026-74463"
  ],
  "published": "2026-08-15T12:28:42Z",
  "summary": "i2c: jz4780: Cache host clock rate at probe to prevent CCF prepare_lock deadlock",
  "details": "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'prepare_lock' mutex and the driver calls i2c_transfer() to update the client's\nchip registers, stalling for the adapter's 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's input clock to calculate bus timings. This call attempts to acquire\nthe blocked CCF 'prepare_lock', 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).",
  "affected": [
    {
      "package": {
        "ecosystem": "Raspberry Pi OS:12",
        "name": "linux"
      },
      "versions": [
        "1:6.1.47-1+rpt4"
      ],
      "ecosystem_specific": {
        "binaries": [
          {
            "binary_name": "linux-image-6.1.0-rpi3-rpi-2712",
            "binary_version": "1:6.1.47-1+rpt4"
          },
          {
            "binary_name": "linux-image-6.1.0-rpi3-rpi-v6",
            "binary_version": "1:6.1.47-1+rpt4"
          },
          {
            "binary_name": "linux-image-6.1.0-rpi3-rpi-v7",
            "binary_version": "1:6.1.47-1+rpt4"
          },
          {
            "binary_name": "linux-image-6.1.0-rpi3-rpi-v7l",
            "binary_version": "1:6.1.47-1+rpt4"
          },
          {
            "binary_name": "linux-image-6.1.0-rpi3-rpi-v8",
            "binary_version": "1:6.1.47-1+rpt4"
          }
        ]
      },
      "database_specific": {
        "per_version": {
          "1:6.1.47-1+rpt4": {
            "linux_commit": "655fc658a15ae7a6f37103754adb39ba52a9a14e",
            "upstream_version": "6.1.47",
            "assessment": "commit ancestry (strak rule)",
            "upstream_fixed": "6.1.183",
            "compiled_filter": false
          }
        }
      }
    }
  ],
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://www.cve.org/CVERecord?id=CVE-2026-74463"
    },
    {
      "type": "FIX",
      "url": "https://git.kernel.org/stable/c/cc111696ef420f6bb552b2526530067977f0b406"
    },
    {
      "type": "FIX",
      "url": "https://git.kernel.org/stable/c/f96a719d9f8a797105ec5cacf568ab128e33391f"
    },
    {
      "type": "FIX",
      "url": "https://git.kernel.org/stable/c/deffad5bb4f8b4f09e46252f24754ddc9960b244"
    },
    {
      "type": "FIX",
      "url": "https://git.kernel.org/stable/c/14429dc1c756c35e106f01ff09cadccb82f5531d"
    },
    {
      "type": "FIX",
      "url": "https://git.kernel.org/stable/c/b6cb47e186abba85a3b08aa3023067ab82577286"
    },
    {
      "type": "FIX",
      "url": "https://git.kernel.org/stable/c/19b783335d62e7a2367436a6e1f1b37da1878360"
    },
    {
      "type": "FIX",
      "url": "https://git.kernel.org/stable/c/aa1944b52d6492c48bdd17046578aa0d953546e6"
    },
    {
      "type": "FIX",
      "url": "https://git.kernel.org/stable/c/d99607c888f26e8a4e9fe9772860cef4aff86bb4"
    }
  ],
  "database_specific": {
    "source": "https://git.kernel.org/pub/scm/linux/security/vulns.git",
    "upstream_modified": "2026-08-19T16:47:12Z"
  }
}