CVE-2026-90182 (GCVE-0-2026-90182)
Vulnerability from cvelistv5
Published
2026-09-17 16:07
Modified
2026-10-21 12:50
Severity ?
Summary
In the Linux kernel, the following vulnerability has been resolved: blk-iocost: clear delay state when freeing policy data iocg_kick_delay() turns sufficiently large debt into an explicit block-cgroup delay with blkcg_set_delay(), setting blkg->use_delay to -1 and incrementing blkcg->congestion_count. Clearing it again depends on iocg_kick_delay() running from the period timer, the waitq timer or the issue path. ioc_pd_free() removes the iocg from active_iocgs and cancels its waitq timer, and no further bios can arrive, so once it has run nothing is left which can reduce the debt and clear the delay. The blkcg stays marked congested for the rest of its life. blk_cgroup_congested() then returns true for every task in that cgroup and its descendants: page_cache_sync_ra() cuts readahead to a single page, page_cache_async_ra() skips it altogether, and __folio_throttle_swaprate() takes swap_avail_lock and schedules a throttle on anonymous folio allocation. Clear it explicitly, after the list removal and the synchronous hrtimer_cancel() so that neither timer processing nor an I/O path can re-arm it. The free callback can also see policy data which was never attached to a blkg, hence the pd->blkg check.
References
Impacted products
Vendor Product Version
Linux Linux Version: 7caa47151ab2e644dd221f741ec7578d9532c9a3
Version: 7caa47151ab2e644dd221f741ec7578d9532c9a3
Version: 7caa47151ab2e644dd221f741ec7578d9532c9a3
Version: 7caa47151ab2e644dd221f741ec7578d9532c9a3
Version: 7caa47151ab2e644dd221f741ec7578d9532c9a3
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{
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      "cpeApplicability": [
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      "descriptions": [
        {
          "lang": "en",
          "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nblk-iocost: clear delay state when freeing policy data\n\niocg_kick_delay() turns sufficiently large debt into an explicit\nblock-cgroup delay with blkcg_set_delay(), setting blkg-\u003euse_delay to\n-1 and incrementing blkcg-\u003econgestion_count.  Clearing it again depends\non iocg_kick_delay() running from the period timer, the waitq timer or\nthe issue path.\n\nioc_pd_free() removes the iocg from active_iocgs and cancels its waitq\ntimer, and no further bios can arrive, so once it has run nothing is\nleft which can reduce the debt and clear the delay.  The blkcg stays\nmarked congested for the rest of its life.\n\nblk_cgroup_congested() then returns true for every task in that cgroup\nand its descendants: page_cache_sync_ra() cuts readahead to a single\npage, page_cache_async_ra() skips it altogether, and\n__folio_throttle_swaprate() takes swap_avail_lock and schedules a\nthrottle on anonymous folio allocation.\n\nClear it explicitly, after the list removal and the synchronous\nhrtimer_cancel() so that neither timer processing nor an I/O path can\nre-arm it.  The free callback can also see policy data which was never\nattached to a blkg, hence the pd-\u003eblkg check."
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-10-21T12:50:21.348Z",
        "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "shortName": "Linux"
      },
      "references": [
        {
          "url": "https://git.kernel.org/stable/c/6b59f976db5def818829fc1eb4efc0a5c8c2f0cf"
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        {
          "url": "https://git.kernel.org/stable/c/8b4d0b1b3079bbe9a5366e2c8020eb22926733b6"
        },
        {
          "url": "https://git.kernel.org/stable/c/b399a88eb8b16c5a1a3645fd49ff507fb82b363c"
        },
        {
          "url": "https://git.kernel.org/stable/c/b9c16db833e3ff15d923282f94dddf0e10fab8c0"
        },
        {
          "url": "https://git.kernel.org/stable/c/97cb95d2148835ae86ff916b145aef332d40439d"
        }
      ],
      "title": "blk-iocost: clear delay state when freeing policy data",
      "x_generator": {
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      }
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  "cveMetadata": {
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    "assignerShortName": "Linux",
    "cveId": "CVE-2026-90182",
    "datePublished": "2026-09-17T16:07:06.388Z",
    "dateReserved": "2026-09-11T19:38:34.791Z",
    "dateUpdated": "2026-10-21T12:50:21.348Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2"
}


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