{"id":"CVE-2026-74463","state":"PUBLISHED","title":"i2c: jz4780: Cache host clock rate at probe to prevent CCF prepare_lock deadlock","description":"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).","publishedAt":"2026-08-15T12:27:03.176Z","updatedAt":"2026-08-19T16:37:02.602Z","severity":null,"assigner":"Linux","products":["Linux Linux"],"affected":[{"vendor":"Linux","product":"Linux","defaultStatus":"unaffected","versions":[{"version":"ba92222ed63a12d09120df9b92f56cc990abac19","status":"affected","lessThan":"cc111696ef420f6bb552b2526530067977f0b406","versionType":"git"},{"version":"ba92222ed63a12d09120df9b92f56cc990abac19","status":"affected","lessThan":"f96a719d9f8a797105ec5cacf568ab128e33391f","versionType":"git"},{"version":"ba92222ed63a12d09120df9b92f56cc990abac19","status":"affected","lessThan":"deffad5bb4f8b4f09e46252f24754ddc9960b244","versionType":"git"},{"version":"ba92222ed63a12d09120df9b92f56cc990abac19","status":"affected","lessThan":"14429dc1c756c35e106f01ff09cadccb82f5531d","versionType":"git"},{"version":"ba92222ed63a12d09120df9b92f56cc990abac19","status":"affected","lessThan":"b6cb47e186abba85a3b08aa3023067ab82577286","versionType":"git"},{"version":"ba92222ed63a12d09120df9b92f56cc990abac19","status":"affected","lessThan":"19b783335d62e7a2367436a6e1f1b37da1878360","versionType":"git"},{"version":"ba92222ed63a12d09120df9b92f56cc990abac19","status":"affected","lessThan":"aa1944b52d6492c48bdd17046578aa0d953546e6","versionType":"git"},{"version":"ba92222ed63a12d09120df9b92f56cc990abac19","status":"affected","lessThan":"d99607c888f26e8a4e9fe9772860cef4aff86bb4","versionType":"git"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["drivers/i2c/busses/i2c-jz4780.c"]},{"vendor":"Linux","product":"Linux","defaultStatus":"affected","versions":[{"version":"4.1","status":"affected"},{"version":"0","status":"unaffected","lessThan":"4.1","versionType":"semver"},{"version":"5.10.265","status":"unaffected","lessThanOrEqual":"5.10.*","versionType":"semver"},{"version":"5.15.216","status":"unaffected","lessThanOrEqual":"5.15.*","versionType":"semver"},{"version":"6.1.183","status":"unaffected","lessThanOrEqual":"6.1.*","versionType":"semver"},{"version":"6.6.151","status":"unaffected","lessThanOrEqual":"6.6.*","versionType":"semver"},{"version":"6.12.103","status":"unaffected","lessThanOrEqual":"6.12.*","versionType":"semver"},{"version":"6.18.44","status":"unaffected","lessThanOrEqual":"6.18.*","versionType":"semver"},{"version":"7.1.8","status":"unaffected","lessThanOrEqual":"7.1.*","versionType":"semver"},{"version":"7.2","status":"unaffected","lessThanOrEqual":"*","versionType":"original_commit_for_fix"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["drivers/i2c/busses/i2c-jz4780.c"]}],"references":["https://git.kernel.org/stable/c/cc111696ef420f6bb552b2526530067977f0b406","https://git.kernel.org/stable/c/f96a719d9f8a797105ec5cacf568ab128e33391f","https://git.kernel.org/stable/c/deffad5bb4f8b4f09e46252f24754ddc9960b244","https://git.kernel.org/stable/c/14429dc1c756c35e106f01ff09cadccb82f5531d","https://git.kernel.org/stable/c/b6cb47e186abba85a3b08aa3023067ab82577286","https://git.kernel.org/stable/c/19b783335d62e7a2367436a6e1f1b37da1878360","https://git.kernel.org/stable/c/aa1944b52d6492c48bdd17046578aa0d953546e6","https://git.kernel.org/stable/c/d99607c888f26e8a4e9fe9772860cef4aff86bb4"],"weaknesses":[],"ingestedAt":"2026-10-29T20:12:58.252Z","source":{"repository":"CVEProject/cvelistV5","path":"cves/2026/74xxx/CVE-2026-74463.json","commit":"556c9d3a8cd17e218bb8e452ba7cd619a384ff47"},"raw":{"dataType":"CVE_RECORD","dataVersion":"5.2","cveMetadata":{"cveId":"CVE-2026-74463","state":"PUBLISHED","datePublished":"2026-08-15T12:27:03.176Z","dateUpdated":"2026-08-19T16:37:02.602Z","assignerShortName":"Linux","assignerOrgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","dateReserved":"2026-08-15T05:44:03.901Z"},"containers":{"cna":{"title":"i2c: jz4780: Cache host clock rate at probe to prevent CCF prepare_lock deadlock","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'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)."}],"affected":[{"vendor":"Linux","product":"Linux","defaultStatus":"unaffected","versions":[{"version":"ba92222ed63a12d09120df9b92f56cc990abac19","status":"affected","lessThan":"cc111696ef420f6bb552b2526530067977f0b406","versionType":"git"},{"version":"ba92222ed63a12d09120df9b92f56cc990abac19","status":"affected","lessThan":"f96a719d9f8a797105ec5cacf568ab128e33391f","versionType":"git"},{"version":"ba92222ed63a12d09120df9b92f56cc990abac19","status":"affected","lessThan":"deffad5bb4f8b4f09e46252f24754ddc9960b244","versionType":"git"},{"version":"ba92222ed63a12d09120df9b92f56cc990abac19","status":"affected","lessThan":"14429dc1c756c35e106f01ff09cadccb82f5531d","versionType":"git"},{"version":"ba92222ed63a12d09120df9b92f56cc990abac19","status":"affected","lessThan":"b6cb47e186abba85a3b08aa3023067ab82577286","versionType":"git"},{"version":"ba92222ed63a12d09120df9b92f56cc990abac19","status":"affected","lessThan":"19b783335d62e7a2367436a6e1f1b37da1878360","versionType":"git"},{"version":"ba92222ed63a12d09120df9b92f56cc990abac19","status":"affected","lessThan":"aa1944b52d6492c48bdd17046578aa0d953546e6","versionType":"git"},{"version":"ba92222ed63a12d09120df9b92f56cc990abac19","status":"affected","lessThan":"d99607c888f26e8a4e9fe9772860cef4aff86bb4","versionType":"git"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["drivers/i2c/busses/i2c-jz4780.c"]},{"vendor":"Linux","product":"Linux","defaultStatus":"affected","versions":[{"version":"4.1","status":"affected"},{"version":"0","status":"unaffected","lessThan":"4.1","versionType":"semver"},{"version":"5.10.265","status":"unaffected","lessThanOrEqual":"5.10.*","versionType":"semver"},{"version":"5.15.216","status":"unaffected","lessThanOrEqual":"5.15.*","versionType":"semver"},{"version":"6.1.183","status":"unaffected","lessThanOrEqual":"6.1.*","versionType":"semver"},{"version":"6.6.151","status":"unaffected","lessThanOrEqual":"6.6.*","versionType":"semver"},{"version":"6.12.103","status":"unaffected","lessThanOrEqual":"6.12.*","versionType":"semver"},{"version":"6.18.44","status":"unaffected","lessThanOrEqual":"6.18.*","versionType":"semver"},{"version":"7.1.8","status":"unaffected","lessThanOrEqual":"7.1.*","versionType":"semver"},{"version":"7.2","status":"unaffected","lessThanOrEqual":"*","versionType":"original_commit_for_fix"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["drivers/i2c/busses/i2c-jz4780.c"]}],"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"},{"url":"https://git.kernel.org/stable/c/19b783335d62e7a2367436a6e1f1b37da1878360"},{"url":"https://git.kernel.org/stable/c/aa1944b52d6492c48bdd17046578aa0d953546e6"},{"url":"https://git.kernel.org/stable/c/d99607c888f26e8a4e9fe9772860cef4aff86bb4"}],"providerMetadata":{"shortName":"Linux","orgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","dateUpdated":"2026-08-19T16:37:02.602Z"},"cpeApplicability":[{"nodes":[{"operator":"OR","negate":false,"cpeMatch":[{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"4.1","versionEndExcluding":"5.10.265"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"4.1","versionEndExcluding":"5.15.216"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"4.1","versionEndExcluding":"6.1.183"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"4.1","versionEndExcluding":"6.6.151"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"4.1","versionEndExcluding":"6.12.103"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"4.1","versionEndExcluding":"6.18.44"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"4.1","versionEndExcluding":"7.1.8"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"4.1","versionEndExcluding":"7.2"}]}]}],"x_generator":{"engine":"bippy-1.2.0"}}}}}