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

Status: upstream: reported C repro on 2026/08/08 20:08
Labels: prio:normal
[Documentation on labels]
Reported-by: syzbot+4c22f022eb39c86b9d19@syzkaller.appspotmail.com
First crash: 7d12h, last: 2d04h
▶ ▼ ✨ AI Jobs (1)
ID Workflow Result Correct Bug Created Started Finished Revision
2f6bb03e assessment-security DenialOfService: ✅ Exploitable: ✅ FilesystemTrigger: ❌ NetworkTrigger: ❌ PeripheralTrigger: ❌ RemoteTrigger: ❌ Unprivileged: ❌ UserNamespace: ❌ VMGuestTrigger: ❌ VMHostTrigger: ❌ ❓ KASAN: slab-use-after-free Read in ntfs_show_options 2026/08/09 04:08 2026/08/09 04:08 2026/08/09 04:33 5d63f80b
▶ ▼ Discussions (2)
Title Replies (including bot) Last reply
[PATCH] ntfs3: Update only the member values without replacing the opts pointer 1 (1) 2026/08/09 06:07
[syzbot] KASAN: slab-use-after-free Read in ntfs_show_options 1 (3) 2026/08/09 06:02
▶ ▼ Last patch testing requests (1)
Created Duration User Patch Repo Result
2026/08/09 02:56 27m eadavis@qq.com patch upstream OK log

Sample crash report:
==================================================================
BUG: KASAN: slab-use-after-free in ntfs_show_options+0x639/0x800 fs/ntfs3/super.c:761
Read of size 4 at addr ffff8880293bb9d4 by task syz-executor151/5970

CPU: 0 UID: 0 PID: 5970 Comm: syz-executor151 Not tainted syzkaller #0 PREEMPT_{RT,(full)} 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/16/2026
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_show_options+0x639/0x800 fs/ntfs3/super.c:761
 show_mountinfo+0x981/0xb70 fs/proc_namespace.c:187
 seq_read_iter+0x8d6/0xcb0 fs/seq_file.c:273
 new_sync_read fs/read_write.c:493 [inline]
 vfs_read+0x59e/0xa90 fs/read_write.c:574
 ksys_read+0x156/0x270 fs/read_write.c:716
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0x174/0x580 arch/x86/entry/syscall_64.c:94
RIP: 0033:0x7fcbe52183fe
Code: 08 0f 85 f5 e2 ff ff 49 89 fb 48 89 f0 48 89 d7 48 89 ce 4c 89 c2 4d 89 ca 4c 8b 44 24 08 4c 8b 4c 24 10 4c 89 5c 24 08 0f 05 <c3> 90 41 57 41 56 4d 89 c6 41 55 4d 89 cd 41 54 55 53 48 83 ec 08
RSP: 002b:00007fcbde1aa198 EFLAGS: 00000246 ORIG_RAX: 0000000000000000
RAX: ffffffffffffffda RBX: 00007fcbde1ab6c0 RCX: 00007fcbe52183fe
RDX: 0000000000001000 RSI: 00007fcbde1aa200 RDI: 0000000000000012
RBP: 00007fcbe525d056 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 00007fcbde1aa200
R13: 0000000000000011 R14: 00007ffdd52256a0 R15: 00007ffdd5225788
 </TASK>

Allocated by task 5975:
 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]
 __kmalloc_cache_noprof+0x3d2/0x6b0 mm/slub.c:5489
 _kmalloc_noprof include/linux/slab.h:988 [inline]
 _kzalloc_noprof include/linux/slab.h:1309 [inline]
 ntfs_init_fs_context+0x55/0x570 fs/ntfs3/super.c:1862
 alloc_fs_context+0x9a3/0xd00 fs/fs_context.c:295
 do_remount fs/namespace.c:3392 [inline]
 path_mount+0xc5e/0x1040 fs/namespace.c:4153
 do_mount fs/namespace.c:4174 [inline]
 __do_sys_mount fs/namespace.c:4390 [inline]
 __se_sys_mount+0x31d/0x420 fs/namespace.c:4367
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0x174/0x580 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

Freed by task 5974:
 kasan_save_stack mm/kasan/common.c:57 [inline]
 kasan_save_track+0x3e/0x80 mm/kasan/common.c:78
 kasan_save_free_info+0x40/0x50 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:2677 [inline]
 slab_free mm/slub.c:6377 [inline]
 kfree+0x1c5/0x6c0 mm/slub.c:6692
 put_fs_context+0x123/0xb00 fs/fs_context.c:498
 do_remount fs/namespace.c:3419 [inline]
 path_mount+0xef9/0x1040 fs/namespace.c:4153
 do_mount fs/namespace.c:4174 [inline]
 __do_sys_mount fs/namespace.c:4390 [inline]
 __se_sys_mount+0x31d/0x420 fs/namespace.c:4367
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0x174/0x580 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

The buggy address belongs to the object at ffff8880293bb9c0
 which belongs to the cache kmalloc-32 of size 32
The buggy address is located 20 bytes inside of
 freed 32-byte region [ffff8880293bb9c0, ffff8880293bb9e0)

The buggy address belongs to the physical page:
page: refcount:0 mapcount:0 mapping:0000000000000000 index:0xffff8880293bb740 pfn:0x293bb
flags: 0x80000000000200(workingset|node=0|zone=1)
page_type: f5(slab)
raw: 0080000000000200 ffff88813ffb3780 ffffea0000c72010 ffffea0000bdd2d0
raw: ffff8880293bb740 000000080040003b 00000000f5000000 0000000000000000
page dumped because: kasan: bad access detected
page_owner tracks the page as allocated
page last allocated via order 0, migratetype Unmovable, gfp_mask 0xd2800(GFP_NOWAIT|__GFP_NORETRY|__GFP_COMP|__GFP_NOMEMALLOC), pid 5406, tgid 5406 (dhcpcd), ts 67741145436, free_ts 67461584725
 set_page_owner include/linux/page_owner.h:32 [inline]
 post_alloc_hook+0x1f9/0x250 mm/page_alloc.c:1859
 prep_new_page mm/page_alloc.c:1867 [inline]
 get_page_from_freelist+0x262a/0x26a0 mm/page_alloc.c:3946
 __alloc_frozen_pages_noprof+0x18d/0x380 mm/page_alloc.c:5304
 alloc_slab_page mm/slub.c:3266 [inline]
 allocate_slab+0x79/0x5e0 mm/slub.c:3380
 new_slab mm/slub.c:3426 [inline]
 refill_objects+0x2d8/0x350 mm/slub.c:7310
 refill_sheaf mm/slub.c:2804 [inline]
 __pcs_replace_empty_main+0x330/0x690 mm/slub.c:4675
 alloc_from_pcs mm/slub.c:4773 [inline]
 slab_alloc_node mm/slub.c:4905 [inline]
 __kmalloc_cache_noprof+0x468/0x6b0 mm/slub.c:5485
 _kmalloc_noprof include/linux/slab.h:988 [inline]
 slab_free_hook mm/slub.c:2629 [inline]
 slab_free mm/slub.c:6377 [inline]
 kmem_cache_free+0x156/0x6c0 mm/slub.c:6504
 remove_vma mm/vma.c:473 [inline]
 vms_complete_munmap_vmas+0x897/0xbe0 mm/vma.c:1361
 do_vmi_align_munmap+0x3bd/0x4d0 mm/vma.c:1604
 do_vmi_munmap+0x252/0x2d0 mm/vma.c:1652
 __vm_munmap+0x241/0x3e0 mm/vma.c:3288
 __do_sys_munmap mm/mmap.c:1079 [inline]
 __se_sys_munmap mm/mmap.c:1076 [inline]
 __x64_sys_munmap+0x60/0x70 mm/mmap.c:1076
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0x174/0x580 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
page last free pid 20 tgid 20 stack trace:
 reset_page_owner include/linux/page_owner.h:25 [inline]
 __free_pages_prepare mm/page_alloc.c:1406 [inline]
 __free_frozen_pages+0x10e7/0x11c0 mm/page_alloc.c:2950
 __tlb_remove_table_free mm/mmu_gather.c:228 [inline]
 tlb_remove_table_rcu+0x85/0x100 mm/mmu_gather.c:291
 rcu_do_batch kernel/rcu/tree.c:2645 [inline]
 rcu_core kernel/rcu/tree.c:2897 [inline]
 rcu_cpu_kthread+0x950/0x1480 kernel/rcu/tree.c:2985
 smpboot_thread_fn+0x57c/0xa80 kernel/smpboot.c:160
 kthread+0x388/0x470 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

Memory state around the buggy address:
 ffff8880293bb880: fa fb fb fb fc fc fc fc fa fb fb fb fc fc fc fc
 ffff8880293bb900: fa fb fb fb fc fc fc fc fa fb fb fb fc fc fc fc
>ffff8880293bb980: fa fb fb fb fc fc fc fc fa fb fb fb fc fc fc fc
                                                 ^
 ffff8880293bba00: fa fb fb fb fc fc fc fc fa fb fb fb fc fc fc fc
 ffff8880293bba80: fa fb fb fb fc fc fc fc fa fb fb fb fc fc fc fc
==================================================================

Crashes (2):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2026/08/11 15:37 upstream f5bbbfec59b4 e611ffe1 .config console log report C ci-upstream-kasan-gce-root KASAN: slab-use-after-free Read in ntfs_show_options
2026/08/06 07:56 upstream 0d8395707651 e611ffe1 .config console log report C ci-upstream-kasan-gce-root KASAN: slab-use-after-free Read in ntfs_show_options
* Struck through repros no longer work on HEAD.