{"id":"CVE-2026-74463","summary":"i2c: jz4780: Cache host clock rate at probe to prevent CCF prepare_lock deadlock","details":"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'prepare_lock' mutex and the driver calls i2c_transfer() to update the client's\nchip registers, stalling for the adapter's 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's input clock to calculate bus timings. This call attempts to acquire\nthe blocked CCF 'prepare_lock', 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).","modified":"2026-08-21T03:30:41.092827361Z","published":"2026-08-15T12:27:03.176Z","database_specific":{"osv_generated_from":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/74xxx/CVE-2026-74463.json","cna_assigner":"Linux"},"references":[{"type":"WEB","url":"https://git.kernel.org/stable/c/14429dc1c756c35e106f01ff09cadccb82f5531d"},{"type":"WEB","url":"https://git.kernel.org/stable/c/19b783335d62e7a2367436a6e1f1b37da1878360"},{"type":"WEB","url":"https://git.kernel.org/stable/c/aa1944b52d6492c48bdd17046578aa0d953546e6"},{"type":"WEB","url":"https://git.kernel.org/stable/c/b6cb47e186abba85a3b08aa3023067ab82577286"},{"type":"WEB","url":"https://git.kernel.org/stable/c/cc111696ef420f6bb552b2526530067977f0b406"},{"type":"WEB","url":"https://git.kernel.org/stable/c/d99607c888f26e8a4e9fe9772860cef4aff86bb4"},{"type":"WEB","url":"https://git.kernel.org/stable/c/deffad5bb4f8b4f09e46252f24754ddc9960b244"},{"type":"WEB","url":"https://git.kernel.org/stable/c/f96a719d9f8a797105ec5cacf568ab128e33391f"},{"type":"ADVISORY","url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/74xxx/CVE-2026-74463.json"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-74463"},{"type":"PACKAGE","url":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git"}],"affected":[{"ranges":[{"type":"GIT","repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","events":[{"introduced":"ba92222ed63a12d09120df9b92f56cc990abac19"},{"fixed":"cc111696ef420f6bb552b2526530067977f0b406"},{"fixed":"f96a719d9f8a797105ec5cacf568ab128e33391f"},{"fixed":"deffad5bb4f8b4f09e46252f24754ddc9960b244"},{"fixed":"14429dc1c756c35e106f01ff09cadccb82f5531d"},{"fixed":"b6cb47e186abba85a3b08aa3023067ab82577286"},{"fixed":"19b783335d62e7a2367436a6e1f1b37da1878360"},{"fixed":"aa1944b52d6492c48bdd17046578aa0d953546e6"},{"fixed":"d99607c888f26e8a4e9fe9772860cef4aff86bb4"}]}],"database_specific":{"source":"https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-74463.json"}},{"package":{"name":"Kernel","ecosystem":"Linux"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"4.1.0"},{"fixed":"5.10.265"}]},{"type":"ECOSYSTEM","events":[{"introduced":"5.11.0"},{"fixed":"5.15.216"}]},{"type":"ECOSYSTEM","events":[{"introduced":"5.16.0"},{"fixed":"6.1.183"}]},{"type":"ECOSYSTEM","events":[{"introduced":"6.2.0"},{"fixed":"6.6.151"}]},{"type":"ECOSYSTEM","events":[{"introduced":"6.7.0"},{"fixed":"6.12.103"}]},{"type":"ECOSYSTEM","events":[{"introduced":"6.13.0"},{"fixed":"6.18.44"}]},{"type":"ECOSYSTEM","events":[{"introduced":"6.19.0"},{"fixed":"7.1.8"}]}],"database_specific":{"source":"https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-74463.json"}}],"schema_version":"1.9.0"}