CVE-2026-74738 (GCVE-0-2026-74738)

Vulnerability from cvelistv5 – Published: 2026-08-26 14:36 – Updated: 2026-08-26 14:36
VLAI
Title
regmap: sdw-mbq: don't call an unset readable_reg callback
Summary
In the Linux kernel, the following vulnerability has been resolved: regmap: sdw-mbq: don't call an unset readable_reg callback regmap_sdw_mbq_poll_busy() decides whether to poll the Function Busy bit by calling ctx->readable_reg(), which is a straight copy of config->readable_reg. That callback is optional: regmap_readable() treats a NULL ->readable_reg as "every register is readable", and drivers rely on that. es9356 and tac5xx2-sdw both build an MBQ regmap without one. Since commit ca1b11b36d82 ("regmap: sdw-mbq: Allow defers on undeferrable controls") the poll runs on every -ENODATA, not only for Controls the driver marked deferrable, so any of those devices answering COMMAND_IGNORED takes the kernel through a NULL function pointer. Treat a missing callback the way the rest of regmap does and poll.
Severity
No CVSS data available.
Assigner
References
Impacted products
Vendor Product Version CPE status
Linux Linux Affected: 5bc493bf0c37c157bf2eb364e55a1c6f8bc43a69 , < 6cf600b276a55a6481462830607a611f32e737c0 (git)
Affected: 5bc493bf0c37c157bf2eb364e55a1c6f8bc43a69 , < 5bd8e897ecf558507142f4553e4526adfc1d6482 (git)
Affected: 5bc493bf0c37c157bf2eb364e55a1c6f8bc43a69 , < 00268f9452d2a0d660aa9c1bb0ca07a994af6a4f (git)
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Linux Linux Affected: 6.14
Unaffected: 0 , < 6.14 (semver)
Unaffected: 6.18.46 , ≤ 6.18.* (semver)
Unaffected: 7.1.10 , ≤ 7.1.* (semver)
Unaffected: 7.2 , ≤ * (original_commit_for_fix)
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{
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          "programFiles": [
            "drivers/base/regmap/regmap-sdw-mbq.c"
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      "descriptions": [
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          "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nregmap: sdw-mbq: don\u0027t call an unset readable_reg callback\n\nregmap_sdw_mbq_poll_busy() decides whether to poll the Function Busy bit\nby calling ctx-\u003ereadable_reg(), which is a straight copy of\nconfig-\u003ereadable_reg. That callback is optional: regmap_readable() treats\na NULL -\u003ereadable_reg as \"every register is readable\", and drivers rely on\nthat. es9356 and tac5xx2-sdw both build an MBQ regmap without one.\n\nSince commit ca1b11b36d82 (\"regmap: sdw-mbq: Allow defers on undeferrable\ncontrols\") the poll runs on every -ENODATA, not only for Controls the\ndriver marked deferrable, so any of those devices answering\nCOMMAND_IGNORED takes the kernel through a NULL function pointer.\n\nTreat a missing callback the way the rest of regmap does and poll."
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-08-26T14:36:51.136Z",
        "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "shortName": "Linux"
      },
      "references": [
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          "url": "https://git.kernel.org/stable/c/6cf600b276a55a6481462830607a611f32e737c0"
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          "url": "https://git.kernel.org/stable/c/5bd8e897ecf558507142f4553e4526adfc1d6482"
        },
        {
          "url": "https://git.kernel.org/stable/c/00268f9452d2a0d660aa9c1bb0ca07a994af6a4f"
        }
      ],
      "title": "regmap: sdw-mbq: don\u0027t call an unset readable_reg callback",
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    "assignerShortName": "Linux",
    "cveId": "CVE-2026-74738",
    "datePublished": "2026-08-26T14:36:51.136Z",
    "dateReserved": "2026-08-15T05:44:03.930Z",
    "dateUpdated": "2026-08-26T14:36:51.136Z",
    "state": "PUBLISHED"
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    "redhat_vex": {
      "aggregate_severity": "Moderate",
      "current_release_date": "2026-08-27T08:25:34+00:00",
      "cve": "CVE-2026-74738",
      "id": "CVE-2026-74738",
      "initial_release_date": "2026-08-26T00:00:00+00:00",
      "product_status:known_affected": "184",
      "product_status:known_not_affected": "90",
      "source": "Red Hat CSAF VEX",
      "status": "final",
      "title": "kernel: regmap: sdw-mbq: don\u0027t call an unset readable_reg callback",
      "url": "https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-74738.json",
      "version": "3"
    }
  }
}



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