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FKIE_CVE-2026-72354

Vulnerability from fkie_nvd - Published: 2026-08-15 06:22 - Updated: 2026-08-17 06:18
Summary
In the Linux kernel, the following vulnerability has been resolved: ntfs: avoid stale runlist element dereference in MFT writeback ntfs_write_mft_block() maps each $MFT record through the $MFT data runlist. For sub-folio clusters it looks up a struct runlist_element under ni->runlist.lock, drops the lock, and later uses rl->length and rl->vcn when choosing folio_sz. That pointer is only borrowed from ni->runlist.rl. Concurrent $MFT allocation extension can merge a replacement runlist under the same lock, and ntfs_rl_realloc() can free the old backing array. If that happens between the lookup and the later folio_sz decision, writeback can dereference freed runlist storage. The buggy scenario involves two paths, with each column showing the order within that path: MFT writeback path: $MFT allocation extension: 1. Look up rl under 1. Extend the $MFT data allocation. ni->runlist.lock. 2. Publish a replacement runlist. 2. Drop ni->runlist.lock. 3. Free the old runlist array. 3. Read rl->length and rl->vcn to choose folio_sz. Compute the remaining run length while ni->runlist.lock is still held, and use that scalar after unlock. This preserves the existing folio sizing decision without carrying a borrowed runlist_element across the lock boundary. Validation reproduced this kernel report: BUG: KASAN: slab-use-after-free in ntfs_mft_writepages+0x1c8d/0x1fb0 Call Trace: <TASK> dump_stack_lvl+0x66/0xa0 print_report+0xce/0x630 ? ntfs_mft_writepages+0x1c8d/0x1fb0 ? srso_alias_return_thunk+0x5/0xfbef5 ? __virt_addr_valid+0x20d/0x410 ? ntfs_mft_writepages+0x1c8d/0x1fb0 kasan_report+0xe0/0x110 ? ntfs_mft_writepages+0x1c8d/0x1fb0 ntfs_mft_writepages+0x1c8d/0x1fb0 ? __pfx_ntfs_mft_writepages+0x10/0x10 ? __pfx___mutex_unlock_slowpath+0x10/0x10 ? srso_alias_return_thunk+0x5/0xfbef5 ? iput+0x92/0xa80 do_writepages+0x219/0x530 ? __pfx_do_writepages+0x10/0x10 __writeback_single_inode+0x117/0xf50 ? do_raw_spin_lock+0x130/0x270 ? __pfx_do_raw_spin_lock+0x10/0x10 ? __pfx___writeback_single_inode+0x10/0x10 ? srso_alias_return_thunk+0x5/0xfbef5 writeback_sb_inodes+0x65b/0x1810 ? srso_alias_return_thunk+0x5/0xfbef5 ? lock_acquire+0x2b8/0x2f0 ? __pfx_writeback_sb_inodes+0x10/0x10 ? lock_release+0x1e0/0x280 ? _raw_spin_unlock+0x23/0x40 ? move_expired_inodes+0x2b8/0x850 __writeback_inodes_wb+0xf4/0x270 ? __pfx___writeback_inodes_wb+0x10/0x10 ? srso_alias_return_thunk+0x5/0xfbef5 ? queue_io+0x2e4/0x410 wb_writeback+0x666/0x880 ? srso_alias_return_thunk+0x5/0xfbef5 ? __pfx_wb_writeback+0x10/0x10 ? srso_alias_return_thunk+0x5/0xfbef5 ? srso_alias_return_thunk+0x5/0xfbef5 ? get_nr_dirty_inodes+0x1c/0x170 wb_workfn+0x75e/0xbb0 ? srso_alias_return_thunk+0x5/0xfbef5 ? _raw_spin_unlock_irqrestore+0x27/0x60 ? __pfx_wb_workfn+0x10/0x10 ? __pfx_debug_object_deactivate+0x10/0x10 ? lock_acquire+0x2b8/0x2f0 ? srso_alias_return_thunk+0x5/0xfbef5 ? lock_release+0x1e0/0x280 process_one_work+0x8d0/0x1870 ? __pfx_process_one_work+0x10/0x10 ? srso_alias_return_thunk+0x5/0xfbef5 worker_thread+0x575/0xf80 ? __pfx_worker_thread+0x10/0x10 kthread+0x2e7/0x3c0 ? __pfx_kthread+0x10/0x10 ret_from_fork+0x576/0x810 ? __pfx_ret_from_fork+0x10/0x10 ? srso_alias_return_thunk+0x5/0xfbef5 ? __switch_to+0x57e/0xe10 ? __switch_to_asm+0x33/0x70 ? __pfx_kthread+0x10/0x10 ret_from_fork_asm+0x1a/0x30 </TASK> Allocated by task 970: kasan_save_stack+0x33/0x60 kasan_save_track+0x14/0x30 __kasan_kmalloc+0xaa/0xb0 __kvmalloc_node_noprof+0x353/0x920 ntfs_rl_realloc+0x3c/0x80 ntfs_runlists_merge+0x1212/0x3010 ntfs_mft_data_extend_allocation_nolock+0x3e0/0x1f40 ntfs_mft_record_alloc+0x1ab4/0x4f10 __ntfs_create+0x680/0x2e50 ntfs_create+0x1e6/0x3a0 path_openat+0x2b55/0x3c10 do_file_open+0x1f4/0x460 do_sys_openat2+0xde/0x170 __x64_sys_openat+0x122/0x1e0 do_syscall_64+0x115/0x6a0 entry_SYSCALL_64_after_hwframe+0x77/0x7f Freed by task 1294: kasan_save_ ---truncated---
Impacted products
Vendor Product Version

{
  "affected": [
    {
      "affectedData": [
        {
          "defaultStatus": "unaffected",
          "product": "Linux",
          "programFiles": [
            "fs/ntfs/mft.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "lessThan": "9a2e36963a3fc52401586657d34e3f1c5a01ea56",
              "status": "affected",
              "version": "115380f9a2f9675c7924563cbba70d40cae8fb81",
              "versionType": "git"
            },
            {
              "lessThan": "81fe702ff1760da32bcd3ef4494b2a33dbeced72",
              "status": "affected",
              "version": "115380f9a2f9675c7924563cbba70d40cae8fb81",
              "versionType": "git"
            }
          ]
        },
        {
          "defaultStatus": "affected",
          "product": "Linux",
          "programFiles": [
            "fs/ntfs/mft.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "status": "affected",
              "version": "7.1"
            },
            {
              "lessThan": "7.1",
              "status": "unaffected",
              "version": "0",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "7.1.*",
              "status": "unaffected",
              "version": "7.1.5",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "*",
              "status": "unaffected",
              "version": "7.2",
              "versionType": "original_commit_for_fix"
            }
          ]
        }
      ],
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
    }
  ],
  "cveTags": [],
  "descriptions": [
    {
      "lang": "en",
      "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nntfs: avoid stale runlist element dereference in MFT writeback\n\nntfs_write_mft_block() maps each $MFT record through the $MFT data\nrunlist. For sub-folio clusters it looks up a struct runlist_element under\nni-\u003erunlist.lock, drops the lock, and later uses rl-\u003elength and rl-\u003evcn\nwhen choosing folio_sz.\n\nThat pointer is only borrowed from ni-\u003erunlist.rl. Concurrent $MFT\nallocation extension can merge a replacement runlist under the same lock,\nand ntfs_rl_realloc() can free the old backing array. If that happens\nbetween the lookup and the later folio_sz decision, writeback can\ndereference freed runlist storage.\n\nThe buggy scenario involves two paths, with each column showing the order\nwithin that path:\n\nMFT writeback path:               $MFT allocation extension:\n1. Look up rl under               1. Extend the $MFT data allocation.\n   ni-\u003erunlist.lock.              2. Publish a replacement runlist.\n2. Drop ni-\u003erunlist.lock.         3. Free the old runlist array.\n3. Read rl-\u003elength and rl-\u003evcn\n   to choose folio_sz.\n\nCompute the remaining run length while ni-\u003erunlist.lock is still held, and\nuse that scalar after unlock. This preserves the existing folio sizing\ndecision without carrying a borrowed runlist_element across the lock\nboundary.\n\nValidation reproduced this kernel report:\nBUG: KASAN: slab-use-after-free in ntfs_mft_writepages+0x1c8d/0x1fb0\n\nCall Trace:\n \u003cTASK\u003e\n dump_stack_lvl+0x66/0xa0\n print_report+0xce/0x630\n ? ntfs_mft_writepages+0x1c8d/0x1fb0\n ? srso_alias_return_thunk+0x5/0xfbef5\n ? __virt_addr_valid+0x20d/0x410\n ? ntfs_mft_writepages+0x1c8d/0x1fb0\n kasan_report+0xe0/0x110\n ? ntfs_mft_writepages+0x1c8d/0x1fb0\n ntfs_mft_writepages+0x1c8d/0x1fb0\n ? __pfx_ntfs_mft_writepages+0x10/0x10\n ? __pfx___mutex_unlock_slowpath+0x10/0x10\n ? srso_alias_return_thunk+0x5/0xfbef5\n ? iput+0x92/0xa80\n do_writepages+0x219/0x530\n ? __pfx_do_writepages+0x10/0x10\n __writeback_single_inode+0x117/0xf50\n ? do_raw_spin_lock+0x130/0x270\n ? __pfx_do_raw_spin_lock+0x10/0x10\n ? __pfx___writeback_single_inode+0x10/0x10\n ? srso_alias_return_thunk+0x5/0xfbef5\n writeback_sb_inodes+0x65b/0x1810\n ? srso_alias_return_thunk+0x5/0xfbef5\n ? lock_acquire+0x2b8/0x2f0\n ? __pfx_writeback_sb_inodes+0x10/0x10\n ? lock_release+0x1e0/0x280\n ? _raw_spin_unlock+0x23/0x40\n ? move_expired_inodes+0x2b8/0x850\n __writeback_inodes_wb+0xf4/0x270\n ? __pfx___writeback_inodes_wb+0x10/0x10\n ? srso_alias_return_thunk+0x5/0xfbef5\n ? queue_io+0x2e4/0x410\n wb_writeback+0x666/0x880\n ? srso_alias_return_thunk+0x5/0xfbef5\n ? __pfx_wb_writeback+0x10/0x10\n ? srso_alias_return_thunk+0x5/0xfbef5\n ? srso_alias_return_thunk+0x5/0xfbef5\n ? get_nr_dirty_inodes+0x1c/0x170\n wb_workfn+0x75e/0xbb0\n ? srso_alias_return_thunk+0x5/0xfbef5\n ? _raw_spin_unlock_irqrestore+0x27/0x60\n ? __pfx_wb_workfn+0x10/0x10\n ? __pfx_debug_object_deactivate+0x10/0x10\n ? lock_acquire+0x2b8/0x2f0\n ? srso_alias_return_thunk+0x5/0xfbef5\n ? lock_release+0x1e0/0x280\n process_one_work+0x8d0/0x1870\n ? __pfx_process_one_work+0x10/0x10\n ? srso_alias_return_thunk+0x5/0xfbef5\n worker_thread+0x575/0xf80\n ? __pfx_worker_thread+0x10/0x10\n kthread+0x2e7/0x3c0\n ? __pfx_kthread+0x10/0x10\n ret_from_fork+0x576/0x810\n ? __pfx_ret_from_fork+0x10/0x10\n ? srso_alias_return_thunk+0x5/0xfbef5\n ? __switch_to+0x57e/0xe10\n ? __switch_to_asm+0x33/0x70\n ? __pfx_kthread+0x10/0x10\n ret_from_fork_asm+0x1a/0x30\n \u003c/TASK\u003e\n\nAllocated by task 970:\n kasan_save_stack+0x33/0x60\n kasan_save_track+0x14/0x30\n __kasan_kmalloc+0xaa/0xb0\n __kvmalloc_node_noprof+0x353/0x920\n ntfs_rl_realloc+0x3c/0x80\n ntfs_runlists_merge+0x1212/0x3010\n ntfs_mft_data_extend_allocation_nolock+0x3e0/0x1f40\n ntfs_mft_record_alloc+0x1ab4/0x4f10\n __ntfs_create+0x680/0x2e50\n ntfs_create+0x1e6/0x3a0\n path_openat+0x2b55/0x3c10\n do_file_open+0x1f4/0x460\n do_sys_openat2+0xde/0x170\n __x64_sys_openat+0x122/0x1e0\n do_syscall_64+0x115/0x6a0\n entry_SYSCALL_64_after_hwframe+0x77/0x7f\n\nFreed by task 1294:\n kasan_save_\n---truncated---"
    }
  ],
  "id": "CVE-2026-72354",
  "lastModified": "2026-08-17T06:18:39.540",
  "metrics": {
    "cvssMetricV31": [
      {
        "cvssData": {
          "attackComplexity": "LOW",
          "attackVector": "NETWORK",
          "availabilityImpact": "HIGH",
          "baseScore": 8.8,
          "baseSeverity": "HIGH",
          "confidentialityImpact": "HIGH",
          "integrityImpact": "HIGH",
          "privilegesRequired": "LOW",
          "scope": "UNCHANGED",
          "userInteraction": "NONE",
          "vectorString": "CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H",
          "version": "3.1"
        },
        "exploitabilityScore": 2.8,
        "impactScore": 5.9,
        "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "type": "Secondary"
      }
    ]
  },
  "published": "2026-08-15T06:22:08.840",
  "references": [
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/81fe702ff1760da32bcd3ef4494b2a33dbeced72"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/9a2e36963a3fc52401586657d34e3f1c5a01ea56"
    }
  ],
  "sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
  "vulnStatus": "Received"
}



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