i2c: jz4780: Cache host clock rate at probe to prevent CCF prepare_lock deadlock

MITRE NVD CVE.ORG JSON API

Summary

CVECVE-2026-74463
StatePUBLISHED
AssignerLinux
Source PriorityCVE Program / NVD first with legacy fallback
Published2026-08-15 13:17:50 UTC
Updated2026-08-15 13:17:50 UTC
DescriptionIn 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).

Vendor Declared Affected Products

SourceVendorProductVersionPlatforms
CNA Linux Linux affected ba92222ed63a12d09120df9b92f56cc990abac19 14429dc1c756c35e106f01ff09cadccb82f5531d git Not specified
CNA Linux Linux affected ba92222ed63a12d09120df9b92f56cc990abac19 b6cb47e186abba85a3b08aa3023067ab82577286 git Not specified
CNA Linux Linux affected ba92222ed63a12d09120df9b92f56cc990abac19 19b783335d62e7a2367436a6e1f1b37da1878360 git Not specified
CNA Linux Linux affected ba92222ed63a12d09120df9b92f56cc990abac19 aa1944b52d6492c48bdd17046578aa0d953546e6 git Not specified
CNA Linux Linux affected ba92222ed63a12d09120df9b92f56cc990abac19 d99607c888f26e8a4e9fe9772860cef4aff86bb4 git Not specified
CNA Linux Linux affected 4.1 Not specified
CNA Linux Linux unaffected 4.1 semver Not specified
CNA Linux Linux unaffected 6.6.151 6.6.* semver Not specified
CNA Linux Linux unaffected 6.12.103 6.12.* semver Not specified
CNA Linux Linux unaffected 6.18.44 6.18.* semver Not specified
CNA Linux Linux unaffected 7.1.8 7.1.* semver Not specified
CNA Linux Linux unaffected 7.2-rc6 * original_commit_for_fix Not specified

References

ReferenceSourceLinkTags
git.kernel.org/stable/c/b6cb47e186abba85a3b08aa3023067ab82577286 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/14429dc1c756c35e106f01ff09cadccb82f5531d 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/aa1944b52d6492c48bdd17046578aa0d953546e6 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/d99607c888f26e8a4e9fe9772860cef4aff86bb4 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/19b783335d62e7a2367436a6e1f1b37da1878360 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
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