{"id":"CVE-2026-89518","state":"PUBLISHED","title":"sched_ext: Fix this_rq() assumptions in dispatch kfuncs","description":"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.","publishedAt":"2026-09-11T19:44:01.222Z","updatedAt":"2026-10-19T08:48:09.565Z","severity":null,"assigner":"Linux","products":["Linux Linux"],"affected":[{"vendor":"Linux","product":"Linux","defaultStatus":"unaffected","versions":[{"version":"4c95380701f58b8112f0b891de8d160e4199e19d","status":"affected","lessThan":"6d1890d3c6137ab523799765ae2de62cc05f116d","versionType":"git"},{"version":"4c95380701f58b8112f0b891de8d160e4199e19d","status":"affected","lessThan":"3dd52416e44a70bc993adb96d2e0d71b9ea21359","versionType":"git"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["kernel/sched/ext/ext.c"]},{"vendor":"Linux","product":"Linux","defaultStatus":"affected","versions":[{"version":"6.19","status":"affected"},{"version":"0","status":"unaffected","lessThan":"6.19","versionType":"semver"},{"version":"7.2.4","status":"unaffected","lessThanOrEqual":"7.2.*","versionType":"semver"},{"version":"7.3","status":"unaffected","lessThanOrEqual":"*","versionType":"original_commit_for_fix"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["kernel/sched/ext/ext.c"]}],"references":["https://git.kernel.org/stable/c/6d1890d3c6137ab523799765ae2de62cc05f116d","https://git.kernel.org/stable/c/3dd52416e44a70bc993adb96d2e0d71b9ea21359"],"weaknesses":[],"ingestedAt":"2026-10-29T20:13:26.108Z","source":{"repository":"CVEProject/cvelistV5","path":"cves/2026/89xxx/CVE-2026-89518.json","commit":"556c9d3a8cd17e218bb8e452ba7cd619a384ff47"},"raw":{"dataType":"CVE_RECORD","dataVersion":"5.2","cveMetadata":{"cveId":"CVE-2026-89518","state":"PUBLISHED","datePublished":"2026-09-11T19:44:01.222Z","dateUpdated":"2026-10-19T08:48:09.565Z","assignerShortName":"Linux","assignerOrgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","dateReserved":"2026-09-11T19:38:34.718Z"},"containers":{"cna":{"title":"sched_ext: Fix this_rq() assumptions in dispatch kfuncs","descriptions":[{"lang":"en","value":"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."}],"affected":[{"vendor":"Linux","product":"Linux","defaultStatus":"unaffected","versions":[{"version":"4c95380701f58b8112f0b891de8d160e4199e19d","status":"affected","lessThan":"6d1890d3c6137ab523799765ae2de62cc05f116d","versionType":"git"},{"version":"4c95380701f58b8112f0b891de8d160e4199e19d","status":"affected","lessThan":"3dd52416e44a70bc993adb96d2e0d71b9ea21359","versionType":"git"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["kernel/sched/ext/ext.c"]},{"vendor":"Linux","product":"Linux","defaultStatus":"affected","versions":[{"version":"6.19","status":"affected"},{"version":"0","status":"unaffected","lessThan":"6.19","versionType":"semver"},{"version":"7.2.4","status":"unaffected","lessThanOrEqual":"7.2.*","versionType":"semver"},{"version":"7.3","status":"unaffected","lessThanOrEqual":"*","versionType":"original_commit_for_fix"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["kernel/sched/ext/ext.c"]}],"references":[{"url":"https://git.kernel.org/stable/c/6d1890d3c6137ab523799765ae2de62cc05f116d"},{"url":"https://git.kernel.org/stable/c/3dd52416e44a70bc993adb96d2e0d71b9ea21359"}],"providerMetadata":{"shortName":"Linux","orgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","dateUpdated":"2026-10-19T08:48:09.565Z"},"cpeApplicability":[{"nodes":[{"operator":"OR","negate":false,"cpeMatch":[{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"6.19","versionEndExcluding":"7.2.4"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"6.19","versionEndExcluding":"7.3"}]}]}],"x_generator":{"engine":"bippy-1.2.0"}}}}}