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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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          "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."
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