FKIE_CVE-2026-93220

Vulnerability from fkie_nvd - Published: 2026-09-24 16:17 - Updated: 2026-09-24 16:17
Severity
Summary
In the Linux kernel, the following vulnerability has been resolved: sched_ext: Keep kick_sync waiting on the rq's own CPU kick_sync_wait_bal_cb() assumes it runs on the rq's CPU from the __schedule() tail: the snapshots it compares against live in that CPU's percpu area and the busy-wait runs with the rq lock dropped and IRQs enabled. However, dispatch can now drop the rq lock while the callback sits queued, and rq lock takers in that window (the sched class change paths, the scx task iterator) flush pending balance callbacks on release, running the callback on a foreign CPU. Such a run compares against unrelated snapshots and can deadlock when the executing CPU is itself a wait target. Bail on a foreign CPU and leave the wait state alone. The wait only observes progress that the resched kicks already guarantee and the rq's next wait picks up the stale cpus_to_sync bits.
References
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/c736ea0fe7b4df920da6bd43a81c5eeecadcc8be
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/e0253dd04beb03e79477c5ef4768b11135687206
Impacted products
Vendor Product Version
To clipboard 

{
  "affected": [
    {
      "affectedData": [
        {
          "defaultStatus": "unaffected",
          "product": "Linux",
          "programFiles": [
            "kernel/sched/ext/ext.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "lessThan": "c736ea0fe7b4df920da6bd43a81c5eeecadcc8be",
              "status": "affected",
              "version": "4c95380701f58b8112f0b891de8d160e4199e19d",
              "versionType": "git"
            },
            {
              "lessThan": "e0253dd04beb03e79477c5ef4768b11135687206",
              "status": "affected",
              "version": "4c95380701f58b8112f0b891de8d160e4199e19d",
              "versionType": "git"
            }
          ]
        },
        {
          "defaultStatus": "affected",
          "product": "Linux",
          "programFiles": [
            "kernel/sched/ext/ext.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "status": "affected",
              "version": "6.19"
            },
            {
              "lessThan": "6.19",
              "status": "unaffected",
              "version": "0",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "7.2.*",
              "status": "unaffected",
              "version": "7.2.4",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "*",
              "status": "unaffected",
              "version": "7.3-rc1",
              "versionType": "original_commit_for_fix"
            }
          ]
        }
      ],
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
    }
  ],
  "cveTags": [],
  "descriptions": [
    {
      "lang": "en",
      "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nsched_ext: Keep kick_sync waiting on the rq\u0027s own CPU\n\nkick_sync_wait_bal_cb() assumes it runs on the rq\u0027s CPU from the\n__schedule() tail: the snapshots it compares against live in that CPU\u0027s\npercpu area and the busy-wait runs with the rq lock dropped and IRQs\nenabled.\n\nHowever, dispatch can now drop the rq lock while the callback sits queued,\nand rq lock takers in that window (the sched class change paths, the scx\ntask iterator) flush pending balance callbacks on release, running the\ncallback on a foreign CPU. Such a run compares against unrelated snapshots\nand can deadlock when the executing CPU is itself a wait target.\n\nBail on a foreign CPU and leave the wait state alone. The wait only observes\nprogress that the resched kicks already guarantee and the rq\u0027s next wait\npicks up the stale cpus_to_sync bits."
    }
  ],
  "id": "CVE-2026-93220",
  "lastModified": "2026-09-24T16:17:17.197",
  "metrics": {},
  "published": "2026-09-24T16:17:17.197",
  "references": [
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/c736ea0fe7b4df920da6bd43a81c5eeecadcc8be"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/e0253dd04beb03e79477c5ef4768b11135687206"
    }
  ],
  "sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
  "vulnStatus": "Received"
}



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