Swapped-page loss via swap counter flag collision
Published Oct 6, 2026 · Updated Oct 6, 2026
Swap accounting error in Linux allows data loss when swapoff tears down a device holding 4 TiB of swapped pages. In mm/swapfile.c, SWAP_USAGE_OFFLIST_BIT uses a bit position derived from atomic_t inside an atomic_long_t usage counter, so swap_usage_in_pages() masks real usage as a flag. With 4 KiB pages and exactly 2^30 swapped pages, swapoff exits as if none remain; frees at that scale also corrupt the count and availability list.
Summary
What happened
Swap accounting error in Linux allows data loss when swapoff tears down a device holding 4 TiB of swapped pages. In mm/swapfile.c, SWAP_USAGE_OFFLIST_BIT uses a bit position derived from atomic_t inside an atomic_long_t usage counter, so swap_usage_in_pages() masks real usage as a flag. With 4 KiB pages and exactly 2^30 swapped pages, swapoff exits as if none remain; frees at that scale also corrupt the count and availability list.
The record
- CVE
- CVE-2026-98226
- Published
- Oct 6, 2026
- Updated
- Oct 6, 2026
- Vendor
- The Linux Kernel Organization
- Product
- Linux
- Classifications
- Unavailable
- Attack vector
- Unavailable
- Privileges
- Unavailable
Timeline
How it unfolded
- Oct 6, 2026CVE publishedPublication date reported by the CVE source.
- Oct 6, 2026Record updatedLatest update available in the CVE record.
Exploitability
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- Affected versionversion=6.14
- Affected versionversion=b228386cf237e659cdf5d8037a19db0b0a06f6b5 <0a41a46859df0d2bd7ed127197aac7c7389c00ed
- Affected versionversion=b228386cf237e659cdf5d8037a19db0b0a06f6b5 <12e9ac7bc5b254048f886bf421e3a15491106c1f
- Affected versionversion=b228386cf237e659cdf5d8037a19db0b0a06f6b5 <7c0d0d6de46076b43a2acaf1026b6648f8434c39
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What is affected?
Published CVSS scores
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Attacks
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Activity data is delayed. The latest report is Sep 28, 2026.
Weakness, pattern, technique
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Public exploit references
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Technologies
Your stack
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