KASAN: slab-use-after-free Read in ntfs_read_hdr

Status: upstream: reported on 2026/06/01 20:12
Subsystems: ntfs3
Labels: actionable prio:high
[Documentation on labels]
Reported-by: syzbot+233bcd55d51543e76e99@syzkaller.appspotmail.com
First crash: 81d, last: 77d
▶ ▼ ✨ AI Jobs (2)
ID Workflow Result Correct Bug Created Started Finished Revision
2b526280 assessment-security DenialOfService: ✅ Exploitable: ✅ FilesystemTrigger: ✅ NetworkTrigger: ❌ PeripheralTrigger: ✅ RemoteTrigger: ❌ Unprivileged: ❌ UserNamespace: ❌ VMGuestTrigger: ❌ VMHostTrigger: ❌ ❓ KASAN: slab-use-after-free Read in ntfs_read_hdr 2026/06/01 19:15 2026/06/01 19:15 2026/06/01 20:16 386cc6da
ac9113d1 moderation Actionable: ✅ ❓ KASAN: slab-use-after-free Read in ntfs_read_hdr 2026/06/01 19:12 2026/06/01 19:12 2026/06/01 20:11 386cc6da
▶ ▼ Discussions (2)
Title Replies (including bot) Last reply
[syzbot] Monthly ntfs3 report (Jun 2026) 0 (1) 2026/06/02 20:32
[syzbot] [ntfs3?] KASAN: slab-use-after-free Read in ntfs_read_hdr 0 (1) 2026/06/01 20:12
▶ ▼ Similar bugs (4)
Kernel Title Rank 🛈 Repro Cause bisect Fix bisect Count Last Reported Patched Status
upstream KMSAN: uninit-value in ntfs_read_hdr (4) ntfs3 7 3 187d 198d 0/29 auto-obsoleted due to no activity on 2026/05/10 14:12
upstream KMSAN: uninit-value in ntfs_read_hdr (3) ntfs3 7 syz, C 6 215d 322d 29/29 fixed on 2026/01/07 12:29
upstream KMSAN: uninit-value in ntfs_read_hdr (2) ntfs3 7 1 464d 460d 0/29 auto-obsoleted due to no activity on 2025/08/06 10:39
upstream KMSAN: uninit-value in ntfs_read_hdr ntfs3 7 15 578d 633d 0/29 auto-obsoleted due to no activity on 2025/03/15 12:38

Sample crash report:
loop0: detected capacity change from 0 to 4096
ntfs3(loop0): Different NTFS sector size (1024) and media sector size (512).
ntfs3(loop0): Mark volume as dirty due to NTFS errors
==================================================================
BUG: KASAN: slab-use-after-free in ntfs_read_hdr+0x938/0xc80 fs/ntfs3/dir.c:368
Read of size 2 at addr ffff888037a69300 by task syz.0.0/5321

CPU: 0 UID: 0 PID: 5321 Comm: syz.0.0 Not tainted syzkaller #0 PREEMPT(full) 
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.3-debian-1.16.3-2 04/01/2014
Call Trace:
 <TASK>
 dump_stack_lvl+0xe8/0x150 lib/dump_stack.c:120
 print_address_description+0x55/0x1e0 mm/kasan/report.c:378
 print_report+0x58/0x70 mm/kasan/report.c:482
 kasan_report+0x117/0x150 mm/kasan/report.c:595
 ntfs_read_hdr+0x938/0xc80 fs/ntfs3/dir.c:368
 ntfs_readdir+0x6f4/0xe40 fs/ntfs3/dir.c:504
 iterate_dir+0x399/0x570 fs/readdir.c:110
 __do_sys_getdents64 fs/readdir.c:399 [inline]
 __se_sys_getdents64+0xf1/0x280 fs/readdir.c:384
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0x15f/0xf80 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f777759ce59
Code: ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 44 00 00 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 e8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007f7778502fe8 EFLAGS: 00000246 ORIG_RAX: 00000000000000d9
RAX: ffffffffffffffda RBX: 00007f7777815fa0 RCX: 00007f777759ce59
RDX: 0000000000001020 RSI: 0000200000003cc0 RDI: 0000000000000004
RBP: 00007f7777632d6f R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f7777816038 R14: 00007f7777815fa0 R15: 00007ffd4e630e18
 </TASK>

Allocated by task 5321:
 kasan_save_stack mm/kasan/common.c:57 [inline]
 kasan_save_track+0x3e/0x80 mm/kasan/common.c:78
 poison_kmalloc_redzone mm/kasan/common.c:398 [inline]
 __kasan_kmalloc+0x93/0xb0 mm/kasan/common.c:415
 kasan_kmalloc include/linux/kasan.h:263 [inline]
 __do_kmalloc_node mm/slub.c:5295 [inline]
 __kmalloc_noprof+0x35c/0x760 mm/slub.c:5307
 kmalloc_noprof include/linux/slab.h:954 [inline]
 mi_init+0x76/0xe0 fs/ntfs3/record.c:105
 ntfs_read_mft fs/ntfs3/inode.c:55 [inline]
 ntfs_iget5+0x36a/0x38e0 fs/ntfs3/inode.c:542
 dir_search_u+0x1fd/0x2e0 fs/ntfs3/dir.c:265
 ntfs_lookup+0x100/0x1d0 fs/ntfs3/namei.c:85
 __lookup_slow+0x2b7/0x410 fs/namei.c:1915
 lookup_slow+0x53/0x70 fs/namei.c:1932
 walk_component fs/namei.c:2278 [inline]
 lookup_last fs/namei.c:2785 [inline]
 path_lookupat+0x3f5/0x8c0 fs/namei.c:2809
 filename_lookup+0x256/0x5d0 fs/namei.c:2838
 do_fchownat+0xfa/0x250 fs/open.c:800
 __do_sys_chown fs/open.c:824 [inline]
 __se_sys_chown fs/open.c:822 [inline]
 __x64_sys_chown+0x82/0xa0 fs/open.c:822
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0x15f/0xf80 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

Freed by task 68:
 kasan_save_stack mm/kasan/common.c:57 [inline]
 kasan_save_track+0x3e/0x80 mm/kasan/common.c:78
 kasan_save_free_info+0x46/0x50 mm/kasan/generic.c:584
 poison_slab_object mm/kasan/common.c:253 [inline]
 __kasan_slab_free+0x5c/0x80 mm/kasan/common.c:285
 kasan_slab_free include/linux/kasan.h:235 [inline]
 slab_free_hook mm/slub.c:2689 [inline]
 slab_free mm/slub.c:6250 [inline]
 kfree+0x1c5/0x640 mm/slub.c:6565
 ni_try_remove_attr_list+0xd78/0xf30 fs/ntfs3/frecord.c:-1
 ni_write_inode+0xa27/0xff0 fs/ntfs3/frecord.c:3191
 write_inode fs/fs-writeback.c:1584 [inline]
 __writeback_single_inode+0x75a/0x10e0 fs/fs-writeback.c:1827
 writeback_sb_inodes+0x979/0x19d0 fs/fs-writeback.c:2056
 __writeback_inodes_wb+0x111/0x240 fs/fs-writeback.c:2132
 wb_writeback+0x459/0xb00 fs/fs-writeback.c:2243
 wb_check_start_all fs/fs-writeback.c:2369 [inline]
 wb_do_writeback fs/fs-writeback.c:2395 [inline]
 wb_workfn+0x921/0xf10 fs/fs-writeback.c:2428
 process_one_work kernel/workqueue.c:3314 [inline]
 process_scheduled_works+0xb5d/0x1860 kernel/workqueue.c:3397
 worker_thread+0xa53/0xfc0 kernel/workqueue.c:3478
 kthread+0x389/0x470 kernel/kthread.c:436
 ret_from_fork+0x514/0xb70 arch/x86/kernel/process.c:158
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245

The buggy address belongs to the object at ffff888037a69000
 which belongs to the cache kmalloc-1k of size 1024
The buggy address is located 768 bytes inside of
 freed 1024-byte region [ffff888037a69000, ffff888037a69400)

The buggy address belongs to the physical page:
page: refcount:0 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x37a68
head: order:2 mapcount:0 entire_mapcount:0 nr_pages_mapped:0 pincount:0
flags: 0x4fff00000000040(head|node=1|zone=1|lastcpupid=0x7ff)
page_type: f5(slab)
raw: 04fff00000000040 ffff88801ac41dc0 dead000000000122 0000000000000000
raw: 0000000000000000 0000000800080008 00000000f5000000 0000000000000000
head: 04fff00000000040 ffff88801ac41dc0 dead000000000122 0000000000000000
head: 0000000000000000 0000000800080008 00000000f5000000 0000000000000000
head: 04fff00000000002 ffffffffffffff01 00000000ffffffff 00000000ffffffff
head: ffffffffffffffff 0000000000000000 00000000ffffffff 0000000000000004
page dumped because: kasan: bad access detected
page_owner tracks the page as allocated
page last allocated via order 2, migratetype Unmovable, gfp_mask 0xd2040(__GFP_IO|__GFP_NOWARN|__GFP_NORETRY|__GFP_COMP|__GFP_NOMEMALLOC), pid 5321, tgid 5320 (syz.0.0), ts 85676669454, free_ts 85638163486
 set_page_owner include/linux/page_owner.h:32 [inline]
 post_alloc_hook+0x22d/0x280 mm/page_alloc.c:1858
 prep_new_page mm/page_alloc.c:1866 [inline]
 get_page_from_freelist+0x24ba/0x2540 mm/page_alloc.c:3946
 __alloc_frozen_pages_noprof+0x18d/0x380 mm/page_alloc.c:5226
 alloc_slab_page mm/slub.c:3278 [inline]
 allocate_slab+0x77/0x660 mm/slub.c:3467
 new_slab mm/slub.c:3525 [inline]
 refill_objects+0x339/0x3d0 mm/slub.c:7271
 refill_sheaf mm/slub.c:2816 [inline]
 __pcs_replace_empty_main+0x321/0x720 mm/slub.c:4651
 alloc_from_pcs mm/slub.c:4749 [inline]
 slab_alloc_node mm/slub.c:4883 [inline]
 __do_kmalloc_node mm/slub.c:5294 [inline]
 __kmalloc_noprof+0x474/0x760 mm/slub.c:5307
 kmalloc_noprof include/linux/slab.h:954 [inline]
 mi_init+0x76/0xe0 fs/ntfs3/record.c:105
 ntfs_read_mft fs/ntfs3/inode.c:55 [inline]
 ntfs_iget5+0x36a/0x38e0 fs/ntfs3/inode.c:542
 dir_search_u+0x1fd/0x2e0 fs/ntfs3/dir.c:265
 ntfs_extend_init+0x247/0x500 fs/ntfs3/fsntfs.c:250
 ntfs_fill_super+0x41ec/0x4580 fs/ntfs3/super.c:1661
 get_tree_bdev_flags+0x431/0x4f0 fs/super.c:1694
 vfs_get_tree+0x92/0x2a0 fs/super.c:1754
 fc_mount fs/namespace.c:1193 [inline]
 do_new_mount_fc fs/namespace.c:3758 [inline]
 do_new_mount+0x341/0xd30 fs/namespace.c:3834
 do_mount fs/namespace.c:4167 [inline]
 __do_sys_mount fs/namespace.c:4383 [inline]
 __se_sys_mount+0x31d/0x420 fs/namespace.c:4360
page last free pid 5321 tgid 5320 stack trace:
 reset_page_owner include/linux/page_owner.h:25 [inline]
 __free_pages_prepare mm/page_alloc.c:1402 [inline]
 __free_frozen_pages+0xbc7/0xd30 mm/page_alloc.c:2943
 stack_depot_save_flags+0x40e/0x810 lib/stackdepot.c:735
 kasan_save_stack mm/kasan/common.c:58 [inline]
 kasan_save_track+0x4f/0x80 mm/kasan/common.c:78
 unpoison_slab_object mm/kasan/common.c:340 [inline]
 __kasan_slab_alloc+0x6c/0x80 mm/kasan/common.c:366
 kasan_slab_alloc include/linux/kasan.h:253 [inline]
 slab_post_alloc_hook mm/slub.c:4569 [inline]
 slab_alloc_node mm/slub.c:4898 [inline]
 kmem_cache_alloc_lru_noprof+0x2b8/0x640 mm/slub.c:4917
 ntfs_alloc_inode+0x28/0x80 fs/ntfs3/super.c:631
 alloc_inode+0x6a/0x1b0 fs/inode.c:345
 iget5_locked+0x4a/0xa0 fs/inode.c:1382
 ntfs_iget5+0xc1/0x38e0 fs/ntfs3/inode.c:535
 ntfs_fill_super+0x3e5a/0x4580 fs/ntfs3/super.c:1615
 get_tree_bdev_flags+0x431/0x4f0 fs/super.c:1694
 vfs_get_tree+0x92/0x2a0 fs/super.c:1754
 fc_mount fs/namespace.c:1193 [inline]
 do_new_mount_fc fs/namespace.c:3758 [inline]
 do_new_mount+0x341/0xd30 fs/namespace.c:3834
 do_mount fs/namespace.c:4167 [inline]
 __do_sys_mount fs/namespace.c:4383 [inline]
 __se_sys_mount+0x31d/0x420 fs/namespace.c:4360
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0x15f/0xf80 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

Memory state around the buggy address:
 ffff888037a69200: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff888037a69280: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
>ffff888037a69300: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
                   ^
 ffff888037a69380: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff888037a69400: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
==================================================================

Crashes (2):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2026/05/20 22:33 upstream df685633c3db 41b8c833 .config console log report [disk image (non-bootable)] [vmlinux] [kernel image] ci-snapshot-upstream-root KASAN: slab-use-after-free Read in ntfs_read_hdr
2026/05/17 00:41 upstream 6916d5703ddf de5aae85 .config console log report [disk image (non-bootable)] [vmlinux] [kernel image] ci-snapshot-upstream-root KASAN: slab-use-after-free Read in ntfs_read_hdr
* Struck through repros no longer work on HEAD.