{"id":"CVE-2026-89518","summary":"sched_ext: Fix this_rq() assumptions in dispatch kfuncs","details":"In the Linux kernel, the following vulnerability has been resolved:\n\nsched_ext: Fix this_rq() assumptions in dispatch kfuncs\n\nUnder core scheduling, dispatch runs from within the core-wide pick and can\ntarget a sibling rq, so ops.dispatch() may execute on a CPU different from\nthe dispatched rq's. Several kfunc paths assumed the two always coincide:\n\n- scx_dsq_move() decided whether an rq lock is held by testing this_rq()'s\n  rq flags and lock-danced accordingly. A dispatch for a sibling took the\n  unlocked-context branch and acquired the source rq lock on top of the\n  already held dispatched rq lock which could deadlock.\n\n- scx_bpf_sub_dispatch() dispatched this_rq() with its stashed\n  sub_dispatch_prev, which is NULL when dispatching for a sibling.\n\n- finish_dispatch(), scx_bpf_dsq_reenq() and scx_bpf_dsq_nr_queued()\n  resolved SCX_DSQ_LOCAL to this CPU's local DSQ rather than the dispatched\n  rq's. The latter two are callable from other rq-locked operations too,\n  where SCX_DSQ_LOCAL now likewise resolves to the op's rq. This changes\n  behavior also without core scheduling, e.g. for ops.enqueue() running a\n  remote wakeup on the waking CPU, and is intended: which CPU happens to\n  execute an operation is incidental, the op's rq is what it is operating\n  on, and the resolution now matches the insert side where SCX_DSQ_LOCAL\n  dispatches land on the task's rq.\n\nUse the rq tracked by scx_locked_rq(), which is set to the dispatched rq\naround ops invocations and NULL in unlocked contexts.","modified":"2026-09-13T03:47:19.011041817Z","published":"2026-09-11T19:44:01.222Z","database_specific":{"cna_assigner":"Linux","osv_generated_from":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/89xxx/CVE-2026-89518.json"},"references":[{"type":"WEB","url":"https://git.kernel.org/stable/c/3dd52416e44a70bc993adb96d2e0d71b9ea21359"},{"type":"WEB","url":"https://git.kernel.org/stable/c/6d1890d3c6137ab523799765ae2de62cc05f116d"},{"type":"ADVISORY","url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/89xxx/CVE-2026-89518.json"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-89518"},{"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":"4c95380701f58b8112f0b891de8d160e4199e19d"},{"fixed":"6d1890d3c6137ab523799765ae2de62cc05f116d"},{"fixed":"3dd52416e44a70bc993adb96d2e0d71b9ea21359"}]}],"database_specific":{"source":"https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-89518.json"}},{"package":{"name":"Kernel","ecosystem":"Linux"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"6.19.0"},{"fixed":"7.2.4"}]}],"database_specific":{"source":"https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-89518.json"}}],"schema_version":"1.9.0"}