CVE-2026-89752 (GCVE-0-2026-89752)
Vulnerability from cvelistv5
Published
2026-09-11 19:46
Modified
2026-10-19 08:52
Severity ?
Summary
In the Linux kernel, the following vulnerability has been resolved: mm: memcg: stop reclaim when a limit update is superseded kernfs serializes file operations only per open file, so separate open files can update the same memory.high or memory.max file concurrently. Both handlers store the new limit before synchronous reclaim, but continue to use the writer's local target in the reclaim loop. If another writer raises or removes the limit, the first writer can continue reclaiming toward a stale target. For memory.max, this can leave the writer looping indefinitely once reclaim retries are exhausted. The OOM path sees sufficient margin under the current limit and returns true without killing, while the writer still compares usage against its stale target and records another OOM event. Check the current limit at the start of each reclaim iteration and stop if it no longer matches the writer's target. Reproducer: Populate a cgroup with anonymous memory and disable swapping. Lower memory.max from one open file, then restore it to "max" through another open file after the new limit becomes visible. Without the patch, the first writer remains blocked and repeatedly increments the OOM event counter. With the patch, it returns normally. This was not motivated by a reported production workload. We found it through automated randomized testing for our cgroup observability work and reduced it to the reproducer above.
References
Impacted products
Vendor Product Version
Linux Linux Version: b6e6edcfa40561e9c8abe5eecf1c96f8e5fd9c6f
Version: b6e6edcfa40561e9c8abe5eecf1c96f8e5fd9c6f
Version: b6e6edcfa40561e9c8abe5eecf1c96f8e5fd9c6f
Version: b6e6edcfa40561e9c8abe5eecf1c96f8e5fd9c6f
Version: b6e6edcfa40561e9c8abe5eecf1c96f8e5fd9c6f
Version: b6e6edcfa40561e9c8abe5eecf1c96f8e5fd9c6f
Version: b6e6edcfa40561e9c8abe5eecf1c96f8e5fd9c6f
Version: b6e6edcfa40561e9c8abe5eecf1c96f8e5fd9c6f
Version: 0ccab5b139971a2a3f48df24d1ee8be2dbf84042
Version: 97729c37439040ec07807f0dbb71ea60ccbafd27
Version: 4.4.7   ≤
Version: 4.5.1   ≤
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      "descriptions": [
        {
          "lang": "en",
          "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nmm: memcg: stop reclaim when a limit update is superseded\n\nkernfs serializes file operations only per open file, so separate open\nfiles can update the same memory.high or memory.max file concurrently. \nBoth handlers store the new limit before synchronous reclaim, but continue\nto use the writer\u0027s local target in the reclaim loop.  If another writer\nraises or removes the limit, the first writer can continue reclaiming\ntoward a stale target.\n\nFor memory.max, this can leave the writer looping indefinitely once\nreclaim retries are exhausted.  The OOM path sees sufficient margin under\nthe current limit and returns true without killing, while the writer still\ncompares usage against its stale target and records another OOM event.\n\nCheck the current limit at the start of each reclaim iteration and stop if\nit no longer matches the writer\u0027s target.\n\nReproducer:\n\nPopulate a cgroup with anonymous memory and disable swapping.  Lower\nmemory.max from one open file, then restore it to \"max\" through another\nopen file after the new limit becomes visible.\n\nWithout the patch, the first writer remains blocked and repeatedly\nincrements the OOM event counter.  With the patch, it returns normally.\n\nThis was not motivated by a reported production workload.  We found it\nthrough automated randomized testing for our cgroup observability work\nand reduced it to the reproducer above."
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-10-19T08:52:05.993Z",
        "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "shortName": "Linux"
      },
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          "url": "https://git.kernel.org/stable/c/4ea0617b9e46d26c0a3e5af00308ea1931cc545d"
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          "url": "https://git.kernel.org/stable/c/5c6f87d33733d96fba66ea4e78cd8b24b4d60a49"
        },
        {
          "url": "https://git.kernel.org/stable/c/8bf21ad3657305e28deafd9ef16a121407496bc3"
        },
        {
          "url": "https://git.kernel.org/stable/c/39ec1e4183a718f448b2e9de681dcbdda18fce42"
        },
        {
          "url": "https://git.kernel.org/stable/c/95d87030cae7764805aa7c621c52871139297cb0"
        },
        {
          "url": "https://git.kernel.org/stable/c/aab391074de96ed601eeca32daef9a8507d436d9"
        },
        {
          "url": "https://git.kernel.org/stable/c/9477820c63cbf4d97114238f3d1ff10dfd6bee3f"
        }
      ],
      "title": "mm: memcg: stop reclaim when a limit update is superseded",
      "x_generator": {
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  "cveMetadata": {
    "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
    "assignerShortName": "Linux",
    "cveId": "CVE-2026-89752",
    "datePublished": "2026-09-11T19:46:56.059Z",
    "dateReserved": "2026-09-11T19:38:34.763Z",
    "dateUpdated": "2026-10-19T08:52:05.993Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2"
}


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