GHSA-63X6-874M-QJJG

Vulnerability from github – Published: 2026-08-15 06:32 – Updated: 2026-08-23 15:32
VLAI
Details

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

i2c: imx: fix locked bus on SMBus block-read of 0 (atomic)

SMBus 3.1 6.5.7 allows a Block Read byte count of 0, but the atomic (polling) path rejects it as -EPROTO. Worse, it returns without a NACK+STOP: the next receive cycle has already started, so the target keeps holding SDA and the bus stays stuck until a power cycle for this i2c controller.

Reading I2DR to obtain the count likewise arms the next byte on the count > I2C_SMBUS_BLOCK_MAX path, which also returned -EPROTO directly and left the bus held.

Handle both: NACK the in-flight dummy byte (TXAK) and extend msgs->len so the existing last-byte handling emits STOP; the dummy byte is discarded. A count of 0 is a valid empty block read; a count above I2C_SMBUS_BLOCK_MAX is still reported as -EPROTO, but only after the bus has been released.

The interrupt-driven path has the same flaw from a later commit and is fixed separately, as it carries a different Fixes: tag and stable range.

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{
  "affected": [],
  "aliases": [
    "CVE-2026-72142"
  ],
  "database_specific": {
    "cwe_ids": [],
    "github_reviewed": false,
    "github_reviewed_at": null,
    "nvd_published_at": "2026-08-15T06:21:31Z",
    "severity": null
  },
  "details": "In the Linux kernel, the following vulnerability has been resolved:\n\ni2c: imx: fix locked bus on SMBus block-read of 0 (atomic)\n\nSMBus 3.1 6.5.7 allows a Block Read byte count of 0, but the atomic\n(polling) path rejects it as -EPROTO. Worse, it returns without a\nNACK+STOP: the next receive cycle has already started, so the target\nkeeps holding SDA and the bus stays stuck until a power cycle for\nthis i2c controller.\n\nReading I2DR to obtain the count likewise arms the next byte on the\ncount \u003e I2C_SMBUS_BLOCK_MAX path, which also returned -EPROTO directly\nand left the bus held.\n\nHandle both: NACK the in-flight dummy byte (TXAK) and extend msgs-\u003elen so\nthe existing last-byte handling emits STOP; the dummy byte is discarded.\nA count of 0 is a valid empty block read; a count above\nI2C_SMBUS_BLOCK_MAX is still reported as -EPROTO, but only after the bus\nhas been released.\n\nThe interrupt-driven path has the same flaw from a later commit and is\nfixed separately, as it carries a different Fixes: tag and stable range.",
  "id": "GHSA-63x6-874m-qjjg",
  "modified": "2026-08-23T15:32:59Z",
  "published": "2026-08-15T06:32:13Z",
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-72142"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/016ef0f6ca4bc9bf0330ac41bd2ea349759643e3"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/0f29df3c3d607a9dbc14aed0e45504ced4d2e7ec"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/38d4947431b2410850409fda016b2ac9f640a4dd"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/60ed00d46616a9232e42ea7a3e3c0273d7cf7543"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/6d2c973926d0612360693bc559be2ffde836151b"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/c882e8cc68fb993700dc21fd6e754001e6297934"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/cb2fc37857693b55909fb77dc2c87cfbc1cdc476"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/e3e8b02d4773cfc5ad561d2e5505efde36c6927a"
    }
  ],
  "schema_version": "1.4.0",
  "severity": []
}



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