CVE-2026-52980 (GCVE-0-2026-52980)

Vulnerability from cvelistv5 – Published: 2026-06-24 16:28 – Updated: 2026-06-24 16:28
VLAI
Title
sched/fair: Clear rel_deadline when initializing forked entities
Summary
In the Linux kernel, the following vulnerability has been resolved: sched/fair: Clear rel_deadline when initializing forked entities A yield-triggered crash can happen when a newly forked sched_entity enters the fair class with se->rel_deadline unexpectedly set. The failing sequence is: 1. A task is forked while se->rel_deadline is still set. 2. __sched_fork() initializes vruntime, vlag and other sched_entity state, but does not clear rel_deadline. 3. On the first enqueue, enqueue_entity() calls place_entity(). 4. Because se->rel_deadline is set, place_entity() treats se->deadline as a relative deadline and converts it to an absolute deadline by adding the current vruntime. 5. However, the forked entity's deadline is not a valid inherited relative deadline for this new scheduling instance, so the conversion produces an abnormally large deadline. 6. If the task later calls sched_yield(), yield_task_fair() advances se->vruntime to se->deadline. 7. The inflated vruntime is then used by the following enqueue path, where the vruntime-derived key can overflow when multiplied by the entity weight. 8. This corrupts cfs_rq->sum_w_vruntime, breaks EEVDF eligibility calculation, and can eventually make all entities appear ineligible. pick_next_entity() may then return NULL unexpectedly, leading to a later NULL dereference. A captured trace shows the effect clearly. Before yield, the entity's vruntime was around: 9834017729983308 After yield_task_fair() executed: se->vruntime = se->deadline the vruntime jumped to: 19668035460670230 and the deadline was later advanced further to: 19668035463470230 This shows that the deadline had already become abnormally large before yield_task_fair() copied it into vruntime. rel_deadline is only meaningful when se->deadline really carries a relative deadline that still needs to be placed against vruntime. A freshly forked sched_entity should not inherit or retain this state. Clear se->rel_deadline in __sched_fork(), together with the other sched_entity runtime state, so that the first enqueue does not interpret the new entity's deadline as a stale relative deadline.
Severity
No CVSS data available.
Assigner
References
Impacted products
Vendor Product Version
Linux Linux Affected: 82e9d0456e06cebe2c89f3c73cdbc9e3805e9437 , < c71bf35caba12bfd9bc23e32b0bcd9e02d1cf1ac (git)
Affected: 82e9d0456e06cebe2c89f3c73cdbc9e3805e9437 , < f3c16e1f4a314a20717ab90a41885f8111a242ab (git)
Affected: 82e9d0456e06cebe2c89f3c73cdbc9e3805e9437 , < 8f4a16200785f49cf02c5b71bdfe7a9dab63f23a (git)
Affected: 82e9d0456e06cebe2c89f3c73cdbc9e3805e9437 , < 3da56dc063cd77b9c0b40add930767fab4e389f3 (git)
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Linux Linux Affected: 6.12
Unaffected: 0 , < 6.12 (semver)
Unaffected: 6.12.91 , ≤ 6.12.* (semver)
Unaffected: 6.18.33 , ≤ 6.18.* (semver)
Unaffected: 7.0.10 , ≤ 7.0.* (semver)
Unaffected: 7.1 , ≤ * (original_commit_for_fix)
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          "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nsched/fair: Clear rel_deadline when initializing forked entities\n\nA yield-triggered crash can happen when a newly forked sched_entity\nenters the fair class with se-\u003erel_deadline unexpectedly set.\n\nThe failing sequence is:\n\n  1. A task is forked while se-\u003erel_deadline is still set.\n  2. __sched_fork() initializes vruntime, vlag and other sched_entity\n     state, but does not clear rel_deadline.\n  3. On the first enqueue, enqueue_entity() calls place_entity().\n  4. Because se-\u003erel_deadline is set, place_entity() treats se-\u003edeadline\n     as a relative deadline and converts it to an absolute deadline by\n     adding the current vruntime.\n  5. However, the forked entity\u0027s deadline is not a valid inherited\n     relative deadline for this new scheduling instance, so the conversion\n     produces an abnormally large deadline.\n  6. If the task later calls sched_yield(), yield_task_fair() advances\n     se-\u003evruntime to se-\u003edeadline.\n  7. The inflated vruntime is then used by the following enqueue path,\n     where the vruntime-derived key can overflow when multiplied by the\n     entity weight.\n  8. This corrupts cfs_rq-\u003esum_w_vruntime, breaks EEVDF eligibility\n     calculation, and can eventually make all entities appear ineligible.\n     pick_next_entity() may then return NULL unexpectedly, leading to a\n     later NULL dereference.\n\nA captured trace shows the effect clearly. Before yield, the entity\u0027s\nvruntime was around:\n\n  9834017729983308\n\nAfter yield_task_fair() executed:\n\n  se-\u003evruntime = se-\u003edeadline\n\nthe vruntime jumped to:\n\n  19668035460670230\n\nand the deadline was later advanced further to:\n\n  19668035463470230\n\nThis shows that the deadline had already become abnormally large before\nyield_task_fair() copied it into vruntime.\n\nrel_deadline is only meaningful when se-\u003edeadline really carries a\nrelative deadline that still needs to be placed against vruntime. A\nfreshly forked sched_entity should not inherit or retain this state.\nClear se-\u003erel_deadline in __sched_fork(), together with the other\nsched_entity runtime state, so that the first enqueue does not interpret\nthe new entity\u0027s deadline as a stale relative deadline."
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-06-24T16:28:56.457Z",
        "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "shortName": "Linux"
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          "url": "https://git.kernel.org/stable/c/f3c16e1f4a314a20717ab90a41885f8111a242ab"
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        {
          "url": "https://git.kernel.org/stable/c/8f4a16200785f49cf02c5b71bdfe7a9dab63f23a"
        },
        {
          "url": "https://git.kernel.org/stable/c/3da56dc063cd77b9c0b40add930767fab4e389f3"
        }
      ],
      "title": "sched/fair: Clear rel_deadline when initializing forked entities",
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    "assignerShortName": "Linux",
    "cveId": "CVE-2026-52980",
    "datePublished": "2026-06-24T16:28:56.457Z",
    "dateReserved": "2026-06-09T07:44:35.376Z",
    "dateUpdated": "2026-06-24T16:28:56.457Z",
    "state": "PUBLISHED"
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      "date": "2026-07-02",
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      "percentile": "0.06377"
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    "nvd": "{\"cve\":{\"id\":\"CVE-2026-52980\",\"sourceIdentifier\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\",\"published\":\"2026-06-24T17:17:08.610\",\"lastModified\":\"2026-06-24T17:17:08.610\",\"vulnStatus\":\"Received\",\"cveTags\":[],\"descriptions\":[{\"lang\":\"en\",\"value\":\"In the Linux kernel, the following vulnerability has been resolved:\\n\\nsched/fair: Clear rel_deadline when initializing forked entities\\n\\nA yield-triggered crash can happen when a newly forked sched_entity\\nenters the fair class with se-\u003erel_deadline unexpectedly set.\\n\\nThe failing sequence is:\\n\\n  1. A task is forked while se-\u003erel_deadline is still set.\\n  2. __sched_fork() initializes vruntime, vlag and other sched_entity\\n     state, but does not clear rel_deadline.\\n  3. On the first enqueue, enqueue_entity() calls place_entity().\\n  4. Because se-\u003erel_deadline is set, place_entity() treats se-\u003edeadline\\n     as a relative deadline and converts it to an absolute deadline by\\n     adding the current vruntime.\\n  5. However, the forked entity\u0027s deadline is not a valid inherited\\n     relative deadline for this new scheduling instance, so the conversion\\n     produces an abnormally large deadline.\\n  6. If the task later calls sched_yield(), yield_task_fair() advances\\n     se-\u003evruntime to se-\u003edeadline.\\n  7. The inflated vruntime is then used by the following enqueue path,\\n     where the vruntime-derived key can overflow when multiplied by the\\n     entity weight.\\n  8. This corrupts cfs_rq-\u003esum_w_vruntime, breaks EEVDF eligibility\\n     calculation, and can eventually make all entities appear ineligible.\\n     pick_next_entity() may then return NULL unexpectedly, leading to a\\n     later NULL dereference.\\n\\nA captured trace shows the effect clearly. Before yield, the entity\u0027s\\nvruntime was around:\\n\\n  9834017729983308\\n\\nAfter yield_task_fair() executed:\\n\\n  se-\u003evruntime = se-\u003edeadline\\n\\nthe vruntime jumped to:\\n\\n  19668035460670230\\n\\nand the deadline was later advanced further to:\\n\\n  19668035463470230\\n\\nThis shows that the deadline had already become abnormally large before\\nyield_task_fair() copied it into vruntime.\\n\\nrel_deadline is only meaningful when se-\u003edeadline really carries a\\nrelative deadline that still needs to be placed against vruntime. A\\nfreshly forked sched_entity should not inherit or retain this state.\\nClear se-\u003erel_deadline in __sched_fork(), together with the other\\nsched_entity runtime state, so that the first enqueue does not interpret\\nthe new entity\u0027s deadline as a stale relative deadline.\"}],\"affected\":[{\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\",\"affectedData\":[{\"vendor\":\"Linux\",\"product\":\"Linux\",\"defaultStatus\":\"unaffected\",\"programFiles\":[\"kernel/sched/core.c\"],\"repo\":\"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git\",\"versions\":[{\"version\":\"82e9d0456e06cebe2c89f3c73cdbc9e3805e9437\",\"lessThan\":\"c71bf35caba12bfd9bc23e32b0bcd9e02d1cf1ac\",\"versionType\":\"git\",\"status\":\"affected\"},{\"version\":\"82e9d0456e06cebe2c89f3c73cdbc9e3805e9437\",\"lessThan\":\"f3c16e1f4a314a20717ab90a41885f8111a242ab\",\"versionType\":\"git\",\"status\":\"affected\"},{\"version\":\"82e9d0456e06cebe2c89f3c73cdbc9e3805e9437\",\"lessThan\":\"8f4a16200785f49cf02c5b71bdfe7a9dab63f23a\",\"versionType\":\"git\",\"status\":\"affected\"},{\"version\":\"82e9d0456e06cebe2c89f3c73cdbc9e3805e9437\",\"lessThan\":\"3da56dc063cd77b9c0b40add930767fab4e389f3\",\"versionType\":\"git\",\"status\":\"affected\"}]},{\"vendor\":\"Linux\",\"product\":\"Linux\",\"defaultStatus\":\"affected\",\"programFiles\":[\"kernel/sched/core.c\"],\"repo\":\"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git\",\"versions\":[{\"version\":\"6.12\",\"status\":\"affected\"},{\"version\":\"0\",\"lessThan\":\"6.12\",\"versionType\":\"semver\",\"status\":\"unaffected\"},{\"version\":\"6.12.91\",\"lessThanOrEqual\":\"6.12.*\",\"versionType\":\"semver\",\"status\":\"unaffected\"},{\"version\":\"6.18.33\",\"lessThanOrEqual\":\"6.18.*\",\"versionType\":\"semver\",\"status\":\"unaffected\"},{\"version\":\"7.0.10\",\"lessThanOrEqual\":\"7.0.*\",\"versionType\":\"semver\",\"status\":\"unaffected\"},{\"version\":\"7.1\",\"lessThanOrEqual\":\"*\",\"versionType\":\"original_commit_for_fix\",\"status\":\"unaffected\"}]}]}],\"metrics\":{},\"references\":[{\"url\":\"https://git.kernel.org/stable/c/3da56dc063cd77b9c0b40add930767fab4e389f3\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\"},{\"url\":\"https://git.kernel.org/stable/c/8f4a16200785f49cf02c5b71bdfe7a9dab63f23a\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\"},{\"url\":\"https://git.kernel.org/stable/c/c71bf35caba12bfd9bc23e32b0bcd9e02d1cf1ac\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\"},{\"url\":\"https://git.kernel.org/stable/c/f3c16e1f4a314a20717ab90a41885f8111a242ab\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\"}]}}"
  }
}


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Forecast uses a logistic model when the trend is rising, or an exponential decay model when the trend is falling. Fitted via linearized least squares.

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  • Seen: The vulnerability was mentioned, discussed, or observed by the user.
  • Confirmed: The vulnerability has been validated from an analyst's perspective.
  • Published Proof of Concept: A public proof of concept is available for this vulnerability.
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  • Not confirmed: The user expressed doubt about the validity of the vulnerability.
  • Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.


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