{"id":"CVE-2026-89518","title":"sched_ext: Fix this_rq() assumptions in dispatch kfuncs","summary":"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.dispatc…","severity":"medium","cvss":5.5,"cvssVector":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H","cvssSource":"vendor","cwe":["CWE-833"],"vendor":"Linux","product":"Linux","affected":["Linux >= 4c95380701f58b8112f0b891de8d160e4199e19d < 6d1890d3c6137ab523799765ae2de62cc05f116d","Linux >= 4c95380701f58b8112f0b891de8d160e4199e19d < 3dd52416e44a70bc993adb96d2e0d71b9ea21359","Linux 6.19"],"published":"2026-09-11","updated":"2026-10-19","sourceUpdated":"2026-10-19T08:48:09.565Z","source":"CVEORG","sourceUrl":"https://www.cve.org/CVERecord?id=CVE-2026-89518","references":[{"url":"https://git.kernel.org/stable/c/6d1890d3c6137ab523799765ae2de62cc05f116d"},{"url":"https://git.kernel.org/stable/c/3dd52416e44a70bc993adb96d2e0d71b9ea21359"},{"url":"https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-89518.json"},{"url":"https://access.redhat.com/security/cve/CVE-2026-89518"},{"url":"https://bugzilla.redhat.com/show_bug.cgi?id=2532018"},{"url":"https://www.cve.org/CVERecord?id=CVE-2026-89518"},{"url":"https://nvd.nist.gov/vuln/detail/CVE-2026-89518"},{"url":"https://git.kernel.org/pub/scm/linux/security/vulns.git/plain/cve/published/2026/CVE-2026-89518.mbox"}],"tags":["cve.org","csaf","vex","red-hat"],"epss":0.00198,"epssPercentile":0.09434,"ingestedAt":"2026-09-14T11:11:19.887Z","slug":"CVE-2026-89518","body":"## Overview\n\nIn 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.\n\n## Affected\n\n- `Linux >= 4c95380701f58b8112f0b891de8d160e4199e19d < 6d1890d3c6137ab523799765ae2de62cc05f116d`\n- `Linux >= 4c95380701f58b8112f0b891de8d160e4199e19d < 3dd52416e44a70bc993adb96d2e0d71b9ea21359`\n- `Linux 6.19`\n\n## Remediation\n\nRefer to the linked advisories for vendor-supplied fixes and affected version ranges.\n\n## Vendor advisories\n\n- **Red Hat VEX** · Moderate · updated 2026-10-17 · [vex](https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-89518.json)","depth":"sunlit","depthScore":30,"depthScoreParts":{"impact":30.3,"likelihood":0,"exploitation":0,"ransomware":0},"changes":[{"seq":202804,"id":"CVE-2026-89518","ts":1789403724492,"field":"cvss","old":null,"new":"5.5"},{"seq":202803,"id":"CVE-2026-89518","ts":1789403724492,"field":"severity","old":"none","new":"medium"},{"seq":109616,"id":"CVE-2026-89518","ts":1789183732660,"field":"cvss","old":null,"new":"4.7"},{"seq":109615,"id":"CVE-2026-89518","ts":1789183732660,"field":"severity","old":"none","new":"medium"}]}