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CVE-2022-49995 (GCVE-0-2022-49995)

Vulnerability from cvelistv5 – Published: 2025-06-18 11:00 – Updated: 2026-08-05 08:57
VLAI
Title
writeback: avoid use-after-free after removing device
Summary
In the Linux kernel, the following vulnerability has been resolved: writeback: avoid use-after-free after removing device When a disk is removed, bdi_unregister gets called to stop further writeback and wait for associated delayed work to complete. However, wb_inode_writeback_end() may schedule bandwidth estimation dwork after this has completed, which can result in the timer attempting to access the just freed bdi_writeback. Fix this by checking if the bdi_writeback is alive, similar to when scheduling writeback work. Since this requires wb->work_lock, and wb_inode_writeback_end() may get called from interrupt, switch wb->work_lock to an irqsafe lock.
Severity
7.8 (High)
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
Assigner
References
Impacted products
Vendor Product Version CPE status
Linux Linux Affected: 45a2966fd64147518dc5bca25f447bd0fb5359ac , < f96b9f7c1676923bce871e728bb49c0dfa5013cc (git)
Affected: 45a2966fd64147518dc5bca25f447bd0fb5359ac , < 9a6c710f3bc10bc9cc23e1c080b53245b7f9d5b7 (git)
Affected: 45a2966fd64147518dc5bca25f447bd0fb5359ac , < f87904c075515f3e1d8f4a7115869d3b914674fd (git)
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Linux Linux Affected: 5.15
Unaffected: 0 , < 5.15 (semver)
Unaffected: 5.15.64 , ≤ 5.15.* (semver)
Unaffected: 5.19.6 , ≤ 5.19.* (semver)
Unaffected: 6.0 , ≤ * (original_commit_for_fix)
guessed Create a notification for this product.
Show details on NVD website
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{
  "containers": {
    "cna": {
      "affected": [
        {
          "defaultStatus": "unaffected",
          "product": "Linux",
          "programFiles": [
            "fs/fs-writeback.c",
            "mm/backing-dev.c",
            "mm/page-writeback.c"
          ],
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          "versions": [
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            },
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              "version": "6.0",
              "versionType": "original_commit_for_fix"
            }
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        }
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          "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nwriteback: avoid use-after-free after removing device\n\nWhen a disk is removed, bdi_unregister gets called to stop further\nwriteback and wait for associated delayed work to complete.  However,\nwb_inode_writeback_end() may schedule bandwidth estimation dwork after\nthis has completed, which can result in the timer attempting to access the\njust freed bdi_writeback.\n\nFix this by checking if the bdi_writeback is alive, similar to when\nscheduling writeback work.\n\nSince this requires wb-\u003ework_lock, and wb_inode_writeback_end() may get\ncalled from interrupt, switch wb-\u003ework_lock to an irqsafe lock."
        }
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            "baseSeverity": "HIGH",
            "vectorString": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H",
            "version": "3.1"
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              "lang": "en",
              "value": "AV:L - The bug is reached via local filesystem writeback and block-device teardown (USB/removable media, del_gendisk \u2192 bdi_unregister), not by processing remote network packets. An attacker needs local access to dirty pages on an affected device.\nAC:L - The attacker can drive both sides of the race by generating writeback I/O and then removing or ejecting the device (e.g. udisks power-off or surprise unplug), and the delayed bw_dwork (~200ms) widens the window; this UAF was hit in practice (KASAN).\nPR:L - An unprivileged user can write to auto-mounted removable storage and trigger or cause its removal without CAP_SYS_ADMIN in the init namespace. Root-only sysfs delete is not required for the worst reasonable removable-media scenario.\nUI:N - The attacker can complete the full sequence (dirty data then eject/remove the device they wrote to) without relying on a separate victim action.\nS:U - This is a host-kernel use-after-free leading to privilege escalation within the same OS security authority, not a VM escape or IOMMU/cross-boundary breakout.\nC:H - Use-after-free of the bdi_writeback object lets an attacker reclaim and control freed kernel memory, enabling arbitrary kernel read primitives.\nI:H - The same UAF is exploitable via heap spray for arbitrary kernel writes and control-flow hijacking through the delayed bandwidth-update work path.\nA:H - The freed bdi_writeback is accessed from delayed work (observed as a KASAN splat), which can oops/panic the kernel even when not fully exploited."
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    "assignerShortName": "Linux",
    "cveId": "CVE-2022-49995",
    "datePublished": "2025-06-18T11:00:55.352Z",
    "dateReserved": "2025-06-18T10:57:27.387Z",
    "dateUpdated": "2026-08-05T08:57:04.391Z",
    "state": "PUBLISHED"
  },
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  "dataVersion": "5.2",
  "vulnerability-lookup:meta": {
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      "percentile": "0.13417"
    },
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However,\\nwb_inode_writeback_end() may schedule bandwidth estimation dwork after\\nthis has completed, which can result in the timer attempting to access the\\njust freed bdi_writeback.\\n\\nFix this by checking if the bdi_writeback is alive, similar to when\\nscheduling writeback work.\\n\\nSince this requires wb-\u003ework_lock, and wb_inode_writeback_end() may get\\ncalled from interrupt, switch wb-\u003ework_lock to an irqsafe lock.\"},{\"lang\":\"es\",\"value\":\"En el kernel de Linux, se ha resuelto la siguiente vulnerabilidad: writeback: evitar el Use-After-Free tras retirar un dispositivo. Al retirar un disco, se llama a bdi_unregister para detener la escritura diferida y esperar a que se complete el trabajo retrasado asociado. Sin embargo, wb_inode_writeback_end() puede programar la estimaci\u00f3n de ancho de banda dwork despu\u00e9s de que esto se haya completado, lo que puede provocar que el temporizador intente acceder al bdi_writeback reci\u00e9n liberado. Para solucionar esto, verifique si bdi_writeback est\u00e1 activo, de forma similar a cuando se programa la escritura diferida. Dado que esto requiere wb-\u0026gt;work_lock y wb_inode_writeback_end() puede ser llamado desde una interrupci\u00f3n, cambie wb-\u0026gt;work_lock a un bloqueo irqsafe.\"}],\"affected\":[{\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\",\"affectedData\":[{\"vendor\":\"Linux\",\"product\":\"Linux\",\"defaultStatus\":\"unaffected\",\"programFiles\":[\"fs/fs-writeback.c\",\"mm/backing-dev.c\",\"mm/page-writeback.c\"],\"repo\":\"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git\",\"versions\":[{\"version\":\"45a2966fd64147518dc5bca25f447bd0fb5359ac\",\"lessThan\":\"f96b9f7c1676923bce871e728bb49c0dfa5013cc\",\"versionType\":\"git\",\"status\":\"affected\"},{\"version\":\"45a2966fd64147518dc5bca25f447bd0fb5359ac\",\"lessThan\":\"9a6c710f3bc10bc9cc23e1c080b53245b7f9d5b7\",\"versionType\":\"git\",\"status\":\"affected\"},{\"version\":\"45a2966fd64147518dc5bca25f447bd0fb5359ac\",\"lessThan\":\"f87904c075515f3e1d8f4a7115869d3b914674fd\",\"versionType\":\"git\",\"status\":\"affected\"}]},{\"vendor\":\"Linux\",\"product\":\"Linux\",\"defaultStatus\":\"affected\",\"programFiles\":[\"fs/fs-writeback.c\",\"mm/backing-dev.c\",\"mm/page-writeback.c\"],\"repo\":\"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git\",\"versions\":[{\"version\":\"5.15\",\"status\":\"affected\"},{\"version\":\"0\",\"lessThan\":\"5.15\",\"versionType\":\"semver\",\"status\":\"unaffected\"},{\"version\":\"5.15.64\",\"lessThanOrEqual\":\"5.15.*\",\"versionType\":\"semver\",\"status\":\"unaffected\"},{\"version\":\"5.19.6\",\"lessThanOrEqual\":\"5.19.*\",\"versionType\":\"semver\",\"status\":\"unaffected\"},{\"version\":\"6.0\",\"lessThanOrEqual\":\"*\",\"versionType\":\"original_commit_for_fix\",\"status\":\"unaffected\"}]}]}],\"metrics\":{\"cvssMetricV31\":[{\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\",\"type\":\"Secondary\",\"cvssData\":{\"version\":\"3.1\",\"vectorString\":\"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H\",\"baseScore\":7.8,\"baseSeverity\":\"HIGH\",\"attackVector\":\"LOCAL\",\"attackComplexity\":\"LOW\",\"privilegesRequired\":\"LOW\",\"userInteraction\":\"NONE\",\"scope\":\"UNCHANGED\",\"confidentialityImpact\":\"HIGH\",\"integrityImpact\":\"HIGH\",\"availabilityImpact\":\"HIGH\"},\"exploitabilityScore\":1.8,\"impactScore\":5.9},{\"source\":\"nvd@nist.gov\",\"type\":\"Primary\",\"cvssData\":{\"version\":\"3.1\",\"vectorString\":\"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H\",\"baseScore\":7.8,\"baseSeverity\":\"HIGH\",\"attackVector\":\"LOCAL\",\"attackComplexity\":\"LOW\",\"privilegesRequired\":\"LOW\",\"userInteraction\":\"NONE\",\"scope\":\"UNCHANGED\",\"confidentialityImpact\":\"HIGH\",\"integrityImpact\":\"HIGH\",\"availabilityImpact\":\"HIGH\"},\"exploitabilityScore\":1.8,\"impactScore\":5.9}]},\"weaknesses\":[{\"source\":\"nvd@nist.gov\",\"type\":\"Primary\",\"description\":[{\"lang\":\"en\",\"value\":\"CWE-416\"}]}],\"configurations\":[{\"nodes\":[{\"operator\":\"OR\",\"negate\":false,\"cpeMatch\":[{\"vulnerable\":true,\"criteria\":\"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*\",\"versionStartIncluding\":\"5.15\",\"versionEndExcluding\":\"5.15.64\",\"matchCriteriaId\":\"7D84F1BC-C9DF-4483-81B0-7377D6BFAEE6\"},{\"vulnerable\":true,\"criteria\":\"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*\",\"versionStartIncluding\":\"5.16\",\"versionEndExcluding\":\"5.19.6\",\"matchCriteriaId\":\"89E99903-E16D-475D-954B-2BAC46C98262\"},{\"vulnerable\":true,\"criteria\":\"cpe:2.3:o:linux:linux_kernel:6.0:rc1:*:*:*:*:*:*\",\"matchCriteriaId\":\"E8BD11A3-8643-49B6-BADE-5029A0117325\"},{\"vulnerable\":true,\"criteria\":\"cpe:2.3:o:linux:linux_kernel:6.0:rc2:*:*:*:*:*:*\",\"matchCriteriaId\":\"5F0AD220-F6A9-4012-8636-155F1B841FAD\"}]}]}],\"references\":[{\"url\":\"https://git.kernel.org/stable/c/9a6c710f3bc10bc9cc23e1c080b53245b7f9d5b7\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\",\"tags\":[\"Patch\"]},{\"url\":\"https://git.kernel.org/stable/c/f87904c075515f3e1d8f4a7115869d3b914674fd\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\",\"tags\":[\"Patch\"]},{\"url\":\"https://git.kernel.org/stable/c/f96b9f7c1676923bce871e728bb49c0dfa5013cc\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\",\"tags\":[\"Patch\"]}]}}",
    "redhat_vex": {
      "aggregate_severity": "Moderate",
      "current_release_date": "2026-08-04T19:41:27+00:00",
      "cve": "CVE-2022-49995",
      "id": "CVE-2022-49995",
      "initial_release_date": "2022-01-01T00:00:00+00:00",
      "product_status:fixed": "605",
      "product_status:known_affected": "36",
      "product_status:known_not_affected": "120",
      "source": "Red Hat CSAF VEX",
      "status": "final",
      "title": "kernel: writeback: avoid use-after-free after removing device",
      "url": "https://security.access.redhat.com/data/csaf/v2/vex/2022/cve-2022-49995.json",
      "version": "3"
    },
    "suse_vex": {
      "aggregate_severity": "moderate",
      "current_release_date": "2026-08-29T02:24:06Z",
      "cve": "CVE-2022-49995",
      "id": "CVE-2022-49995",
      "initial_release_date": "2025-06-19T03:44:31Z",
      "product_status:known_affected": "344",
      "product_status:known_not_affected": "389",
      "product_status:recommended": "253",
      "source": "SUSE CSAF VEX",
      "status": "interim",
      "title": "SUSE CVE CVE-2022-49995",
      "url": "https://ftp.suse.com/pub/projects/security/csaf-vex/cve-2022-49995.json",
      "version": "41"
    }
  }
}



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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.

Sightings

Author Source Type Date Other

Nomenclature

  • 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.
  • Exploited: The vulnerability was observed as exploited by the user who reported the sighting.
  • Patched: The vulnerability was observed as successfully patched by the user who reported the sighting.
  • Not exploited: The vulnerability was not observed as exploited by the user who reported the sighting.
  • 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.


Detection rules are retrieved from Rulezet.