CVE-2026-98443 (GCVE-0-2026-98443)

Vulnerability from cvelistv5 – Published: 2026-10-18 15:14 – Updated: 2026-10-24 14:08
VLAI
Title
xfs: fix cursor and pointer handling when recovering iunlink buckets
Summary
In the Linux kernel, the following vulnerability has been resolved: xfs: fix cursor and pointer handling when recovering iunlink buckets LOLLM pointed out a bug in xlog_recover_iunlink_bucket: 1. We don't null out prev_ip after releasing it, which can lead to UAF problems if the inodegc flush call in the loop fails. at which point I noticed even more bugs: 2. If the inodegc flush inside the loop fails, we also leak @ip. 3. We set prev_agino to agino having already advanced agino, which results in inodes with i_prev_unlinked set to itself. 4. If we exit the bottom of the loop with prev_ip set, then prev_ip aliases ip and we also set its i_prev_unlinked to itself. Bugs 3 and 4 introduce loops into the unlinked list, though these loops don't surface because we immediately flush each unlinked inode after loading it. Fix all of these issues.
Severity
7.8 (High)
CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H
Assigner
Linux CNA under the mitre root
CNA scorecard D 53/100 over 7056 records in the last 180 days details
References
Impacted products
Vendor Product Version CPE status
Linux Linux Affected: 04755d2e5821b3afbaadd09fe5df58d04de36484 , < 47a948ba653a463d429e02fda2f06a3d6b78666d (git)
Affected: 04755d2e5821b3afbaadd09fe5df58d04de36484 , < 8c9d5b8a96d6b93eb24e07b4163c89341ba29bd1 (git)
Affected: 04755d2e5821b3afbaadd09fe5df58d04de36484 , < 66a2179d02668f8df44b1a249899006f3ba38ea0 (git)
Affected: 04755d2e5821b3afbaadd09fe5df58d04de36484 , < 961c717e6bf0e53c2c2b1fe4aef1add9390fedab (git)
Affected: 04755d2e5821b3afbaadd09fe5df58d04de36484 , < 65f39d09d73718611cee40399179323b5d4ead00 (git)
guessed Create a notification for this product.
Linux Linux Affected: 6.0
Unaffected: 0 , < 6.0 (semver)
Unaffected: 6.6.160 , ≤ 6.6.* (semver)
Unaffected: 6.12.113 , ≤ 6.12.* (semver)
Unaffected: 6.18.55 , ≤ 6.18.* (semver)
Unaffected: 7.2.9 , ≤ 7.2.* (semver)
Unaffected: 7.3 , ≤ * (original_commit_for_fix)
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        }
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              "value": "AV:L - Malformed agi_unlinked, di_next_unlinked, and inode-fork data enter from a local XFS image when mount(2) reaches xlog_recover_iunlink_bucket through xfs_log_mount_finish and xlog_recover_finish; no remote protocol carries these bytes.\nAC:L - The image author can create a dirty log, two inodes in one unlinked bucket, and corrupt external btree metadata that makes xfs_inactive fail through xfs_inodegc_flush. This deterministically enters the stale-prev_ip error path without requiring an uncontrollable hardware fault.\nPR:N - The attacker only creates and supplies the XFS image, requiring no target account or capability. XFS omits FS_USERNS_MOUNT, so the privileged mount_capable check applies to the interacting victim and is captured by UI:R.\nUI:R - A victim or administrator must mount the attacker-supplied dirty XFS image so xfs_log_mount_finish invokes xlog_recover_finish and the patched xlog_recover_iunlink_bucket.\nS:U - The stale xfs_inode and resulting memory corruption affect the mounting host kernel within its existing security authority; no VM, IOMMU, or other isolation boundary is crossed.\nC:H - After xfs_inodegc_flush makes prev_ip reclaimable, the stale pointer can reference an xfs_inode_cache object reclaimed and replaced before the second xfs_irele; reuse and secondary UAF of the replacement inode support kernel-memory disclosure.\nI:H - The second xfs_irele can decrement i_count in a reused xfs_inode, prematurely destroying a live replacement inode and producing secondary use-after-free memory corruption exploitable for control-flow hijacking.\nA:H - The stale xfs_irele can dereference a freed inode or underflow its reference count; DEBUG_VFS BUGs on the invalid inode state/count, while non-debug builds can corrupt a replacement inode and later oops or panic."
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}



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