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
Linux CNA under the mitre root
CNA scorecard D 53/100 over 6641 records in the last 180 days details
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)
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Show details on NVD website
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              "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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      "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",
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      "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"
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  }
}



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