GHSA-6W6J-FMCG-FGJ3
Vulnerability from github – Published: 2026-09-11 21:31 – Updated: 2026-09-13 09:32In the Linux kernel, the following vulnerability has been resolved:
md/raid10: fix still_degraded being inverted in raid10_sync_request()
Commit fe6a19d40ceb ("md/md-bitmap: merge md_bitmap_start_sync() into bitmap_operations") converted still_degraded from int to bool, but inverted the assignment in the loop that checks whether the array will still be degraded after the current device is recovered: "still_degraded = 1" became "still_degraded = false".
As a result, recovering a device while another mirror is still missing calls md_bitmap_start_sync() with degraded == false, which clears bitmap bits that the still-missing device needs. When that device is re-added, its bitmap-based recovery finds the bits already cleared and skips every region written while the array was degraded, so it is marked In_sync while holding stale data: silent corruption.
Reproducer (raid10 near=2, 4 disks, internal bitmap): - fail and remove one disk of each mirror pair - write to the degraded array - re-add both disks and let recovery finish - "check" reports mismatch_cnt=262272 after 256 MiB of degraded writes and file contents differ; the second disk's "recovery" completes in milliseconds because everything is skipped
The same conversion in raid1 got it right (still_degraded = true). Restore the correct value.
{
"affected": [],
"aliases": [
"CVE-2026-89558"
],
"database_specific": {
"cwe_ids": [],
"github_reviewed": false,
"github_reviewed_at": null,
"nvd_published_at": "2026-09-11T20:19:39Z",
"severity": "CRITICAL"
},
"details": "In the Linux kernel, the following vulnerability has been resolved:\n\nmd/raid10: fix still_degraded being inverted in raid10_sync_request()\n\nCommit fe6a19d40ceb (\"md/md-bitmap: merge md_bitmap_start_sync() into\nbitmap_operations\") converted still_degraded from int to bool, but\ninverted the assignment in the loop that checks whether the array will\nstill be degraded after the current device is recovered:\n\"still_degraded = 1\" became \"still_degraded = false\".\n\nAs a result, recovering a device while another mirror is still missing\ncalls md_bitmap_start_sync() with degraded == false, which clears bitmap\nbits that the still-missing device needs. When that device is re-added,\nits bitmap-based recovery finds the bits already cleared and skips every\nregion written while the array was degraded, so it is marked In_sync\nwhile holding stale data: silent corruption.\n\nReproducer (raid10 near=2, 4 disks, internal bitmap):\n - fail and remove one disk of each mirror pair\n - write to the degraded array\n - re-add both disks and let recovery finish\n - \"check\" reports mismatch_cnt=262272 after 256 MiB of degraded\n writes and file contents differ; the second disk\u0027s \"recovery\"\n completes in milliseconds because everything is skipped\n\nThe same conversion in raid1 got it right (still_degraded = true).\nRestore the correct value.",
"id": "GHSA-6w6j-fmcg-fgj3",
"modified": "2026-09-13T09:32:18Z",
"published": "2026-09-11T21:31:31Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2026-89558"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/00449d752bee9c8787f42ea1bf533a9fb17f9b6b"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/0efabe6229dc683dbf6eeebd0f9fddc7971ed420"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/47f1441b281decde6954a2fa82b4131637d685ac"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/9bb8da6ecb330a5b1ac9b96f1e55f134a7aef1d4"
}
],
"schema_version": "1.4.0",
"severity": [
{
"score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H",
"type": "CVSS_V3"
}
]
}
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