CVE-2026-99171 (GCVE-0-2026-99171)

Vulnerability from cvelistv5 – Published: 2026-10-28 10:35 – Updated: 2026-10-30 12:42
VLAI
Title
ntfs3: free the sbi after a grace period
Summary
In the Linux kernel, the following vulnerability has been resolved: ntfs3: free the sbi after a grace period If the "nocase" mount option ntfs3 uses custom hash and dentry compare functions. Both access ntfs3 superblock private information in rcu pathwalk. ntfs_put_super() and ntfs3_kill_sb() drop the info without any rcu delay. A lookup that's still inside the filesystem when the last reference to the mount is dropped causes a UAF. With a pathwalk held up in ntfs_d_hash() while the last reference to the mount goes away: BUG: KASAN: slab-use-after-free in ntfs_nls_to_utf16+0x752/0x940 Read of size 8 at addr ff1100010453c850 by task walker/99 Call Trace: <TASK> ntfs_nls_to_utf16+0x752/0x940 ntfs_d_hash+0x22b/0x500 link_path_walk+0x11ad/0x1d30 path_lookupat+0x63/0xb00 filename_lookup+0x1f1/0x5b0 vfs_statx+0xd7/0x3b0 [...] Allocated by task 95: __kmalloc_cache_noprof+0x249/0x560 ntfs_init_fs_context+0x2db/0x5a0 alloc_fs_context+0x52e/0xc70 [...] Freed by task 98: kfree+0x1db/0x5b0 deactivate_locked_super+0x9c/0xf0 cleanup_mnt+0x9f/0x130 task_work_run+0x131/0x250 The bug is currently masked by the grace period in namespace_unlock() for umount(2). Keep the necessary information until the filesystem private info is freed and free it with an rcu delay. ntfs3_free_sbi() now runs from an rcu callback and drops the upcase table via ntfs_put_shared(). So switch s_shared_lock over to spin_lock_bh(). Otherwise the callback can deadlock against a task holding the lock on the same cpu.
Severity
No CVSS data available.
Assigner
Linux CNA under the mitre root
CNA scorecard D 53/100 over 6639 records in the last 180 days details
References
Impacted products
Vendor Product Version CPE status
Linux Linux Affected: a3a956c78efaa202b1d75190136671cf6e87bfbe , < c39150784a801dbbfaf4fbfa284cb610552a5039 (git)
Affected: a3a956c78efaa202b1d75190136671cf6e87bfbe , < 36e6753daf9bb64563dcb5a3bb22f7699d973fa2 (git)
Affected: a3a956c78efaa202b1d75190136671cf6e87bfbe , < c8b1a4840467930e01f1a9374d991d7a8a2896c1 (git)
Affected: a3a956c78efaa202b1d75190136671cf6e87bfbe , < 7abecef26a9be8f9de70659a3092250461a52072 (git)
Affected: a3a956c78efaa202b1d75190136671cf6e87bfbe , < c01b091b06412d3b1b53d8c2925f6de586c8a2fc (git)
guessed Create a notification for this product.
Linux Linux Affected: 6.2
Unaffected: 0 , < 6.2 (semver)
Unaffected: 6.6.161 , ≤ 6.6.* (semver)
Unaffected: 6.12.115 , ≤ 6.12.* (semver)
Unaffected: 6.18.59 , ≤ 6.18.* (semver)
Unaffected: 7.2.13 , ≤ 7.2.* (semver)
Unaffected: 7.3 , ≤ * (original_commit_for_fix)
guessed Create a notification for this product.
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          "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nntfs3: free the sbi after a grace period\n\nIf the \"nocase\" mount option ntfs3 uses custom hash and dentry compare\nfunctions. Both access ntfs3 superblock private information in rcu\npathwalk. ntfs_put_super() and ntfs3_kill_sb() drop the info without any\nrcu delay. A lookup that\u0027s still inside the filesystem when the last\nreference to the mount is dropped causes a UAF. With a pathwalk held up\nin ntfs_d_hash() while the last reference to the mount goes away:\n\n  BUG: KASAN: slab-use-after-free in ntfs_nls_to_utf16+0x752/0x940\n  Read of size 8 at addr ff1100010453c850 by task walker/99\n  Call Trace:\n   \u003cTASK\u003e\n   ntfs_nls_to_utf16+0x752/0x940\n   ntfs_d_hash+0x22b/0x500\n   link_path_walk+0x11ad/0x1d30\n   path_lookupat+0x63/0xb00\n   filename_lookup+0x1f1/0x5b0\n   vfs_statx+0xd7/0x3b0\n  [...]\n  Allocated by task 95:\n   __kmalloc_cache_noprof+0x249/0x560\n   ntfs_init_fs_context+0x2db/0x5a0\n   alloc_fs_context+0x52e/0xc70\n  [...]\n  Freed by task 98:\n   kfree+0x1db/0x5b0\n   deactivate_locked_super+0x9c/0xf0\n   cleanup_mnt+0x9f/0x130\n   task_work_run+0x131/0x250\n\nThe bug is currently masked by the grace period in namespace_unlock()\nfor umount(2). Keep the necessary information until the filesystem\nprivate info is freed and free it with an rcu delay.\n\nntfs3_free_sbi() now runs from an rcu callback and drops the upcase\ntable via ntfs_put_shared(). So switch s_shared_lock over to\nspin_lock_bh(). Otherwise the callback can deadlock against a task\nholding the lock on the same cpu."
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            "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nntfs3: free the sbi after a grace period\n\nIf the \"nocase\" mount option ntfs3 uses custom hash and dentry compare\nfunctions. Both access ntfs3 superblock private information in rcu\npathwalk. ntfs_put_super() and ntfs3_kill_sb() drop the info without any\nrcu delay. A lookup that\u0027s still inside the filesystem when the last\nreference to the mount is dropped causes a UAF. With a pathwalk held up\nin ntfs_d_hash() while the last reference to the mount goes away:\n\n  BUG: KASAN: slab-use-after-free in ntfs_nls_to_utf16+0x752/0x940\n  Read of size 8 at addr ff1100010453c850 by task walker/99\n  Call Trace:\n   \u003cTASK\u003e\n   ntfs_nls_to_utf16+0x752/0x940\n   ntfs_d_hash+0x22b/0x500\n   link_path_walk+0x11ad/0x1d30\n   path_lookupat+0x63/0xb00\n   filename_lookup+0x1f1/0x5b0\n   vfs_statx+0xd7/0x3b0\n  [...]\n  Allocated by task 95:\n   __kmalloc_cache_noprof+0x249/0x560\n   ntfs_init_fs_context+0x2db/0x5a0\n   alloc_fs_context+0x52e/0xc70\n  [...]\n  Freed by task 98:\n   kfree+0x1db/0x5b0\n   deactivate_locked_super+0x9c/0xf0\n   cleanup_mnt+0x9f/0x130\n   task_work_run+0x131/0x250\n\nThe bug is currently masked by the grace period in namespace_unlock()\nfor umount(2). Keep the necessary information until the filesystem\nprivate info is freed and free it with an rcu delay.\n\nntfs3_free_sbi() now runs from an rcu callback and drops the upcase\ntable via ntfs_put_shared(). So switch s_shared_lock over to\nspin_lock_bh(). Otherwise the callback can deadlock against a task\nholding the lock on the same cpu."
          }
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        "id": "CVE-2026-99171",
        "lastModified": "2026-10-30T13:21:50.760",
        "metrics": {},
        "published": "2026-10-28T11:17:37.660",
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      "source": "Red Hat CSAF VEX",
      "status": "final",
      "title": "kernel: ntfs3: free the sbi after a grace period",
      "url": "https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-99171.json",
      "version": "3"
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  }
}



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