Bug 2532221 (CVE-2026-89558)

Summary: CVE-2026-89558 kernel: md/raid10: fix still_degraded being inverted in raid10_sync_request()
Product: [Other] Security Response Reporter: OSIDB Bzimport <bzimport>
Component: vulnerabilityAssignee: Product Security DevOps Team <prodsec-dev>
Status: NEW --- QA Contact:
Severity: medium Docs Contact:
Priority: medium    
Version: unspecifiedCC: akhatavk, aos-team-art-private, asdas, dpaolell, jdelft, jupierce, lgarciaa, mbiarnes, ppalepu, ppostler, prdhamdh, rhel-process-autobot, sghai, sidsharm, suppawar, vlaad, watson-tool-maintainers
Target Milestone: ---Keywords: Security
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Hardware: All   
OS: Linux   
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A flaw was found in the Linux kernel's md/raid10 (RAID10) driver. This vulnerability occurs when a RAID10 array is in a degraded state and a device is being recovered while another mirror is still missing. Due to an inverted boolean value, the system incorrectly clears necessary bitmap bits, causing subsequent recovery operations to skip regions with stale data. This can lead to silent data corruption on the re-added device, impacting data integrity.
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Description OSIDB Bzimport 2026-09-11 21:28:34 UTC
In 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.