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---
Metrics
Affected Vendors & Products
| Vendors | Products |
|---|---|
| Linux |
|
No data.
No data.
No data.
References
History
Sat, 15 Aug 2026 06:00:00 +0000
| Type | Values Removed | Values Added |
|---|---|---|
| Description | 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--- | |
| Title | ntfs: avoid stale runlist element dereference in MFT writeback | |
| First Time appeared |
Linux
Linux linux Kernel |
|
| CPEs | cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:* | |
| Vendors & Products |
Linux
Linux linux Kernel |
|
| References |
|
MITRE
Status: PUBLISHED
Assigner: Linux
Published:
Updated: 2026-08-15T05:55:56.163Z
Reserved: 2026-08-09T03:40:39.921Z
Link: CVE-2026-72354
Vulnrichment
No data.
NVD
Status : Received
Published: 2026-08-15T06:22:08.840
Modified: 2026-08-15T06:22:08.840
Link: CVE-2026-72354
Redhat
No data.
OpenCVE Enrichment
No data.