CVE-2026-74463 (GCVE-0-2026-74463)
Vulnerability from cvelistv5
Published
2026-08-15 12:27
Modified
2026-08-19 16:37
Severity ?
VLAI Severity ?
EPSS score ?
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
Impacted products
| Vendor | Product | Version | ||
|---|---|---|---|---|
| Linux | Linux |
Version: ba92222ed63a12d09120df9b92f56cc990abac19 Version: ba92222ed63a12d09120df9b92f56cc990abac19 Version: ba92222ed63a12d09120df9b92f56cc990abac19 Version: ba92222ed63a12d09120df9b92f56cc990abac19 Version: ba92222ed63a12d09120df9b92f56cc990abac19 Version: ba92222ed63a12d09120df9b92f56cc990abac19 Version: ba92222ed63a12d09120df9b92f56cc990abac19 Version: ba92222ed63a12d09120df9b92f56cc990abac19 |
||
{
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{
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{
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"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)."
}
],
"providerMetadata": {
"dateUpdated": "2026-08-19T16:37:02.602Z",
"orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"shortName": "Linux"
},
"references": [
{
"url": "https://git.kernel.org/stable/c/cc111696ef420f6bb552b2526530067977f0b406"
},
{
"url": "https://git.kernel.org/stable/c/f96a719d9f8a797105ec5cacf568ab128e33391f"
},
{
"url": "https://git.kernel.org/stable/c/deffad5bb4f8b4f09e46252f24754ddc9960b244"
},
{
"url": "https://git.kernel.org/stable/c/14429dc1c756c35e106f01ff09cadccb82f5531d"
},
{
"url": "https://git.kernel.org/stable/c/b6cb47e186abba85a3b08aa3023067ab82577286"
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{
"url": "https://git.kernel.org/stable/c/19b783335d62e7a2367436a6e1f1b37da1878360"
},
{
"url": "https://git.kernel.org/stable/c/aa1944b52d6492c48bdd17046578aa0d953546e6"
},
{
"url": "https://git.kernel.org/stable/c/d99607c888f26e8a4e9fe9772860cef4aff86bb4"
}
],
"title": "i2c: jz4780: Cache host clock rate at probe to prevent CCF prepare_lock deadlock",
"x_generator": {
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}
},
"cveMetadata": {
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"assignerShortName": "Linux",
"cveId": "CVE-2026-74463",
"datePublished": "2026-08-15T12:27:03.176Z",
"dateReserved": "2026-08-15T05:44:03.901Z",
"dateUpdated": "2026-08-19T16:37:02.602Z",
"state": "PUBLISHED"
},
"dataType": "CVE_RECORD",
"dataVersion": "5.2"
}
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Sightings
| Author | Source | Type | Date |
|---|
Nomenclature
- Seen: The vulnerability was mentioned, discussed, or seen somewhere by the user.
- Confirmed: The vulnerability is confirmed from an analyst perspective.
- Published Proof of Concept: A public proof of concept is available for this vulnerability.
- Exploited: This vulnerability was exploited and seen by the user reporting the sighting.
- Patched: This vulnerability was successfully patched by the user reporting the sighting.
- Not exploited: This vulnerability was not exploited or seen by the user reporting the sighting.
- Not confirmed: The user expresses doubt about the veracity of the vulnerability.
- Not patched: This vulnerability was not successfully patched by the user reporting the sighting.
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