GHSA-45RW-88GP-H7JX
Vulnerability from github – Published: 2026-09-11 21:31 – Updated: 2026-09-11 21:31In the Linux kernel, the following vulnerability has been resolved:
sched_ext: Fix this_rq() assumptions in dispatch kfuncs
Under core scheduling, dispatch runs from within the core-wide pick and can target a sibling rq, so ops.dispatch() may execute on a CPU different from the dispatched rq's. Several kfunc paths assumed the two always coincide:
-
scx_dsq_move() decided whether an rq lock is held by testing this_rq()'s rq flags and lock-danced accordingly. A dispatch for a sibling took the unlocked-context branch and acquired the source rq lock on top of the already held dispatched rq lock which could deadlock.
-
scx_bpf_sub_dispatch() dispatched this_rq() with its stashed sub_dispatch_prev, which is NULL when dispatching for a sibling.
-
finish_dispatch(), scx_bpf_dsq_reenq() and scx_bpf_dsq_nr_queued() resolved SCX_DSQ_LOCAL to this CPU's local DSQ rather than the dispatched rq's. The latter two are callable from other rq-locked operations too, where SCX_DSQ_LOCAL now likewise resolves to the op's rq. This changes behavior also without core scheduling, e.g. for ops.enqueue() running a remote wakeup on the waking CPU, and is intended: which CPU happens to execute an operation is incidental, the op's rq is what it is operating on, and the resolution now matches the insert side where SCX_DSQ_LOCAL dispatches land on the task's rq.
Use the rq tracked by scx_locked_rq(), which is set to the dispatched rq around ops invocations and NULL in unlocked contexts.
{
"affected": [],
"aliases": [
"CVE-2026-89518"
],
"database_specific": {
"cwe_ids": [],
"github_reviewed": false,
"github_reviewed_at": null,
"nvd_published_at": "2026-09-11T20:19:34Z",
"severity": null
},
"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\u0027s. Several kfunc paths assumed the two always coincide:\n\n- scx_dsq_move() decided whether an rq lock is held by testing this_rq()\u0027s\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\u0027s local DSQ rather than the dispatched\n rq\u0027s. The latter two are callable from other rq-locked operations too,\n where SCX_DSQ_LOCAL now likewise resolves to the op\u0027s 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\u0027s 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\u0027s 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.",
"id": "GHSA-45rw-88gp-h7jx",
"modified": "2026-09-11T21:31:30Z",
"published": "2026-09-11T21:31:30Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2026-89518"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/3dd52416e44a70bc993adb96d2e0d71b9ea21359"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/6d1890d3c6137ab523799765ae2de62cc05f116d"
}
],
"schema_version": "1.4.0",
"severity": []
}
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