{"id":"CVE-2025-68780","summary":"sched/deadline: only set free_cpus for online runqueues","details":"In the Linux kernel, the following vulnerability has been resolved:\n\nsched/deadline: only set free_cpus for online runqueues\n\nCommit 16b269436b72 (\"sched/deadline: Modify cpudl::free_cpus\nto reflect rd-\u003eonline\") introduced the cpudl_set/clear_freecpu\nfunctions to allow the cpu_dl::free_cpus mask to be manipulated\nby the deadline scheduler class rq_on/offline callbacks so the\nmask would also reflect this state.\n\nCommit 9659e1eeee28 (\"sched/deadline: Remove cpu_active_mask\nfrom cpudl_find()\") removed the check of the cpu_active_mask to\nsave some processing on the premise that the cpudl::free_cpus\nmask already reflected the runqueue online state.\n\nUnfortunately, there are cases where it is possible for the\ncpudl_clear function to set the free_cpus bit for a CPU when the\ndeadline runqueue is offline. When this occurs while a CPU is\nconnected to the default root domain the flag may retain the bad\nstate after the CPU has been unplugged. Later, a different CPU\nthat is transitioning through the default root domain may push a\ndeadline task to the powered down CPU when cpudl_find sees its\nfree_cpus bit is set. If this happens the task will not have the\nopportunity to run.\n\nOne example is outlined here:\nhttps://lore.kernel.org/lkml/20250110233010.2339521-1-opendmb@gmail.com\n\nAnother occurs when the last deadline task is migrated from a\nCPU that has an offlined runqueue. The dequeue_task member of\nthe deadline scheduler class will eventually call cpudl_clear\nand set the free_cpus bit for the CPU.\n\nThis commit modifies the cpudl_clear function to be aware of the\nonline state of the deadline runqueue so that the free_cpus mask\ncan be updated appropriately.\n\nIt is no longer necessary to manage the mask outside of the\ncpudl_set/clear functions so the cpudl_set/clear_freecpu\nfunctions are removed. In addition, since the free_cpus mask is\nnow only updated under the cpudl lock the code was changed to\nuse the non-atomic __cpumask functions.","modified":"2026-04-02T13:03:48.810639Z","published":"2026-01-13T15:28:55.483Z","related":["MGASA-2026-0017","MGASA-2026-0018"],"database_specific":{"cna_assigner":"Linux","osv_generated_from":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2025/68xxx/CVE-2025-68780.json"},"references":[{"type":"WEB","url":"https://git.kernel.org/stable/c/382748c05e58a9f1935f5a653c352422375566ea"},{"type":"WEB","url":"https://git.kernel.org/stable/c/3ed049fbfb4d75b4e0b8ab54c934f485129d5dc8"},{"type":"WEB","url":"https://git.kernel.org/stable/c/9019e399684e3cc68c4a3f050e268f74d69c1317"},{"type":"WEB","url":"https://git.kernel.org/stable/c/91e448e69aca4bb0ba2e998eb3e555644db7322b"},{"type":"WEB","url":"https://git.kernel.org/stable/c/dbc61834b0412435df21c71410562d933e4eba49"},{"type":"WEB","url":"https://git.kernel.org/stable/c/fb36846cbcc936954f2ad2bffdff13d16c0be08a"},{"type":"ADVISORY","url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2025/68xxx/CVE-2025-68780.json"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2025-68780"},{"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":"9659e1eeee28f7025b6545934d644d19e9c6e603"},{"fixed":"9019e399684e3cc68c4a3f050e268f74d69c1317"},{"fixed":"fb36846cbcc936954f2ad2bffdff13d16c0be08a"},{"fixed":"91e448e69aca4bb0ba2e998eb3e555644db7322b"},{"fixed":"dbc61834b0412435df21c71410562d933e4eba49"},{"fixed":"3ed049fbfb4d75b4e0b8ab54c934f485129d5dc8"},{"fixed":"382748c05e58a9f1935f5a653c352422375566ea"}]}],"database_specific":{"source":"https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2025-68780.json"}},{"package":{"name":"Kernel","ecosystem":"Linux"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"4.0.0"},{"fixed":"5.15.198"}]},{"type":"ECOSYSTEM","events":[{"introduced":"5.16.0"},{"fixed":"6.1.160"}]},{"type":"ECOSYSTEM","events":[{"introduced":"6.2.0"},{"fixed":"6.6.120"}]},{"type":"ECOSYSTEM","events":[{"introduced":"6.7.0"},{"fixed":"6.12.64"}]},{"type":"ECOSYSTEM","events":[{"introduced":"6.13.0"},{"fixed":"6.18.3"}]}],"database_specific":{"source":"https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2025-68780.json"}}],"schema_version":"1.7.5"}