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KASAN: use-after-free Read in incfs_free_mount_info

Status: premoderation: reported on 2026/01/18 22:40
Reported-by: syzbot+5184cd9aebccb43b2981@syzkaller.appspotmail.com
First crash: 24d, last: 20h58m
▶ ▼ Similar bugs (2)
Kernel Title Rank 🛈 Repro Cause bisect Fix bisect Count Last Reported Patched Status
android-5-10 KASAN: use-after-free Read in incfs_free_mount_info 19 61 1d09h 24d 0/2 premoderation: reported on 2026/01/19 00:38
android-5-15 KASAN: use-after-free Read in incfs_free_mount_info 19 13 1h34m 18d 0/2 premoderation: reported on 2026/01/25 07:55

Sample crash report:
R13: 00007fb259431c3b R14: 000055555e7b64e8 R15: 00007ffd1928fe60
 </TASK>
---[ end trace 0000000000000000 ]---
==================================================================
BUG: KASAN: use-after-free in fast_dput+0x1e9/0x290 fs/dcache.c:778
Read of size 4 at addr ffff88814a0cb000 by task syz-executor/9035

CPU: 1 PID: 9035 Comm: syz-executor Tainted: G        W          syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/24/2026
Call Trace:
 <TASK>
 __dump_stack+0x21/0x24 lib/dump_stack.c:88
 dump_stack_lvl+0x110/0x170 lib/dump_stack.c:106
 print_address_description+0x71/0x200 mm/kasan/report.c:316
 print_report+0x4a/0x60 mm/kasan/report.c:420
 kasan_report+0x122/0x150 mm/kasan/report.c:524
 __asan_report_load4_noabort+0x14/0x20 mm/kasan/report_generic.c:350
 fast_dput+0x1e9/0x290 fs/dcache.c:778
 dput+0x21/0x80 fs/dcache.c:905
 incfs_free_mount_info+0x60/0x200 fs/incfs/data_mgmt.c:166
 incfs_kill_sb+0x1b8/0x220 fs/incfs/vfs.c:2003
 deactivate_locked_super+0xb5/0x120 fs/super.c:334
 deactivate_super+0xaf/0xe0 fs/super.c:365
 cleanup_mnt+0x474/0x500 fs/namespace.c:1191
 __cleanup_mnt+0x19/0x20 fs/namespace.c:1198
 task_work_run+0x1e1/0x250 kernel/task_work.c:203
 exit_task_work include/linux/task_work.h:39 [inline]
 do_exit+0xa35/0x2660 kernel/exit.c:886
 do_group_exit+0x210/0x2d0 kernel/exit.c:1028
 __do_sys_exit_group kernel/exit.c:1039 [inline]
 __se_sys_exit_group kernel/exit.c:1037 [inline]
 __x64_sys_exit_group+0x3f/0x40 kernel/exit.c:1037
 x64_sys_call+0x7b4/0x9a0 arch/x86/include/generated/asm/syscalls_64.h:232
 do_syscall_x64 arch/x86/entry/common.c:46 [inline]
 do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:76
 entry_SYSCALL_64_after_hwframe+0x68/0xd2
RIP: 0033:0x7fb25939bf79
Code: Unable to access opcode bytes at 0x7fb25939bf4f.
RSP: 002b:00007ffd1928dad8 EFLAGS: 00000246 ORIG_RAX: 00000000000000e7
RAX: ffffffffffffffda RBX: 00007fb259431c9b RCX: 00007fb25939bf79
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000001
RBP: 0000000000000009 R08: 0000000000000000 R09: 00007fb259431c3b
R10: 0000000000000000 R11: 0000000000000246 R12: 00007ffd1928ed90
R13: 00007fb259431c3b R14: 000055555e7b64e8 R15: 00007ffd1928fe60
 </TASK>

Allocated by task 10400:
 kasan_save_stack mm/kasan/common.c:46 [inline]
 kasan_set_track+0x4b/0x70 mm/kasan/common.c:53
 kasan_save_alloc_info+0x25/0x30 mm/kasan/generic.c:505
 __kasan_slab_alloc+0x72/0x80 mm/kasan/common.c:334
 kasan_slab_alloc include/linux/kasan.h:202 [inline]
 slab_post_alloc_hook+0x4f/0x2d0 mm/slab.h:768
 slab_alloc_node mm/slub.c:3382 [inline]
 slab_alloc mm/slub.c:3392 [inline]
 __kmem_cache_alloc_lru mm/slub.c:3399 [inline]
 kmem_cache_alloc_lru+0x104/0x280 mm/slub.c:3415
 __d_alloc+0x34/0x6c0 fs/dcache.c:1774
 d_alloc fs/dcache.c:1854 [inline]
 d_alloc_parallel+0xe2/0x12e0 fs/dcache.c:2647
 __lookup_slow+0x14f/0x410 fs/namei.c:1682
 lookup_one_len+0x19d/0x2e0 fs/namei.c:2747
 incfs_lookup_dentry+0x60/0xb0 fs/incfs/data_mgmt.c:210
 open_or_create_special_dir+0x4f/0x1d0 fs/incfs/vfs.c:475
 incfs_mount_fs+0x42f/0x890 fs/incfs/vfs.c:1890
 legacy_get_tree+0xfe/0x1a0 fs/fs_context.c:632
 vfs_get_tree+0x9a/0x270 fs/super.c:1575
 do_new_mount+0x25a/0xa20 fs/namespace.c:3078
 path_mount+0x659/0xfc0 fs/namespace.c:3408
 do_mount fs/namespace.c:3421 [inline]
 __do_sys_mount fs/namespace.c:3629 [inline]
 __se_sys_mount+0x320/0x390 fs/namespace.c:3606
 __x64_sys_mount+0xbf/0xd0 fs/namespace.c:3606
 x64_sys_call+0x65d/0x9a0 arch/x86/include/generated/asm/syscalls_64.h:166
 do_syscall_x64 arch/x86/entry/common.c:46 [inline]
 do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:76
 entry_SYSCALL_64_after_hwframe+0x68/0xd2

Freed by task 23:
 kasan_save_stack mm/kasan/common.c:46 [inline]
 kasan_set_track+0x4b/0x70 mm/kasan/common.c:53
 kasan_save_free_info+0x31/0x50 mm/kasan/generic.c:516
 ____kasan_slab_free+0x132/0x180 mm/kasan/common.c:242
 __kasan_slab_free+0x11/0x20 mm/kasan/common.c:250
 kasan_slab_free include/linux/kasan.h:178 [inline]
 slab_free_hook mm/slub.c:1750 [inline]
 slab_free_freelist_hook+0xc2/0x190 mm/slub.c:1776
 slab_free mm/slub.c:3712 [inline]
 kmem_cache_free+0x12d/0x300 mm/slub.c:3737
 __d_free+0x23/0x30 fs/dcache.c:298
 rcu_do_batch+0x52a/0xbc0 kernel/rcu/tree.c:2297
 rcu_core+0x5c3/0xe80 kernel/rcu/tree.c:2557
 rcu_core_si+0x9/0x10 kernel/rcu/tree.c:2574
 handle_softirqs+0x1d7/0x600 kernel/softirq.c:642
 run_ksoftirqd+0x28/0x30 kernel/softirq.c:1019
 smpboot_thread_fn+0x4a0/0x910 kernel/smpboot.c:164
 kthread+0x281/0x320 kernel/kthread.c:386
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:295

Last potentially related work creation:
 kasan_save_stack+0x3a/0x60 mm/kasan/common.c:46
 __kasan_record_aux_stack+0xb6/0xc0 mm/kasan/generic.c:486
 kasan_record_aux_stack_noalloc+0xb/0x10 mm/kasan/generic.c:496
 __call_rcu_common kernel/rcu/tree.c:2807 [inline]
 call_rcu+0xcf/0xf90 kernel/rcu/tree.c:2926
 dentry_free+0xbd/0x150 fs/dcache.c:-1
 __dentry_kill+0x529/0x670 fs/dcache.c:625
 dentry_kill+0xc0/0x2a0 fs/dcache.c:-1
 dput+0x42/0x80 fs/dcache.c:918
 incfs_free_mount_info+0x60/0x200 fs/incfs/data_mgmt.c:166
 incfs_kill_sb+0x1b8/0x220 fs/incfs/vfs.c:2003
 deactivate_locked_super+0xb5/0x120 fs/super.c:334
 deactivate_super+0xaf/0xe0 fs/super.c:365
 cleanup_mnt+0x474/0x500 fs/namespace.c:1191
 __cleanup_mnt+0x19/0x20 fs/namespace.c:1198
 task_work_run+0x1e1/0x250 kernel/task_work.c:203
 exit_task_work include/linux/task_work.h:39 [inline]
 do_exit+0xa35/0x2660 kernel/exit.c:886
 do_group_exit+0x210/0x2d0 kernel/exit.c:1028
 __do_sys_exit_group kernel/exit.c:1039 [inline]
 __se_sys_exit_group kernel/exit.c:1037 [inline]
 __x64_sys_exit_group+0x3f/0x40 kernel/exit.c:1037
 x64_sys_call+0x7b4/0x9a0 arch/x86/include/generated/asm/syscalls_64.h:232
 do_syscall_x64 arch/x86/entry/common.c:46 [inline]
 do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:76
 entry_SYSCALL_64_after_hwframe+0x68/0xd2

Second to last potentially related work creation:
 kasan_save_stack+0x3a/0x60 mm/kasan/common.c:46
 __kasan_record_aux_stack+0xb6/0xc0 mm/kasan/generic.c:486
 kasan_record_aux_stack_noalloc+0xb/0x10 mm/kasan/generic.c:496
 __call_rcu_common kernel/rcu/tree.c:2807 [inline]
 call_rcu+0xcf/0xf90 kernel/rcu/tree.c:2926
 dentry_free+0xbd/0x150 fs/dcache.c:-1
 __dentry_kill+0x529/0x670 fs/dcache.c:625
 shrink_dentry_list+0x38e/0x500 fs/dcache.c:1206
 shrink_dcache_parent+0xa9/0x270 fs/dcache.c:-1
 do_one_tree+0x27/0x150 fs/dcache.c:1687
 shrink_dcache_for_umount+0x6a/0x110 fs/dcache.c:1704
 generic_shutdown_super+0x66/0x370 fs/super.c:475
 kill_block_super+0x7f/0xf0 fs/super.c:1472
 kill_f2fs_super+0x303/0x3b0 fs/f2fs/super.c:4868
 deactivate_locked_super+0xb5/0x120 fs/super.c:334
 deactivate_super+0xaf/0xe0 fs/super.c:365
 cleanup_mnt+0x474/0x500 fs/namespace.c:1191
 __cleanup_mnt+0x19/0x20 fs/namespace.c:1198
 task_work_run+0x1e1/0x250 kernel/task_work.c:203
 resume_user_mode_work include/linux/resume_user_mode.h:49 [inline]
 exit_to_user_mode_loop+0x9b/0xb0 kernel/entry/common.c:177
 exit_to_user_mode_prepare+0x87/0xd0 kernel/entry/common.c:210
 __syscall_exit_to_user_mode_work kernel/entry/common.c:292 [inline]
 syscall_exit_to_user_mode+0x1a/0x30 kernel/entry/common.c:303
 do_syscall_64+0x58/0xa0 arch/x86/entry/common.c:82
 entry_SYSCALL_64_after_hwframe+0x68/0xd2

The buggy address belongs to the object at ffff88814a0cb000
 which belongs to the cache dentry of size 208
The buggy address is located 0 bytes inside of
 208-byte region [ffff88814a0cb000, ffff88814a0cb0d0)

The buggy address belongs to the physical page:
page:ffffea00052832c0 refcount:1 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x14a0cb
flags: 0x4000000000000200(slab|zone=1)
raw: 4000000000000200 ffffea0004609f40 dead000000000004 ffff8881001edc80
raw: 0000000000000000 00000000000f000f 00000001ffffffff 0000000000000000
page dumped because: kasan: bad access detected
page_owner tracks the page as allocated
page last allocated via order 0, migratetype Reclaimable, gfp_mask 0x112cd0(GFP_USER|__GFP_NOWARN|__GFP_NORETRY|__GFP_RECLAIMABLE), pid 7374, tgid 7374 (syz-executor), ts 370681423718, free_ts 367244262194
 set_page_owner include/linux/page_owner.h:33 [inline]
 post_alloc_hook+0x1f5/0x210 mm/page_alloc.c:2643
 prep_new_page+0x1c/0x110 mm/page_alloc.c:2650
 get_page_from_freelist+0x2d12/0x2d80 mm/page_alloc.c:4554
 __alloc_pages+0x1d9/0x480 mm/page_alloc.c:5868
 alloc_slab_page+0x6e/0xf0 include/linux/gfp.h:-1
 allocate_slab mm/slub.c:1967 [inline]
 new_slab+0x98/0x3d0 mm/slub.c:2020
 ___slab_alloc+0x6bd/0xb20 mm/slub.c:3177
 __slab_alloc+0x5e/0xa0 mm/slub.c:3263
 slab_alloc_node mm/slub.c:3348 [inline]
 slab_alloc mm/slub.c:3392 [inline]
 __kmem_cache_alloc_lru mm/slub.c:3399 [inline]
 kmem_cache_alloc_lru+0x144/0x280 mm/slub.c:3415
 __d_alloc+0x34/0x6c0 fs/dcache.c:1774
 d_alloc_anon fs/dcache.c:1875 [inline]
 d_alloc_cursor+0x41/0xd0 fs/dcache.c:1881
 dcache_dir_open+0x3b/0x80 fs/libfs.c:83
 do_dentry_open+0x88e/0x1260 fs/open.c:884
 vfs_open+0x73/0x80 fs/open.c:1017
 do_open fs/namei.c:3633 [inline]
 path_openat+0x2700/0x2f80 fs/namei.c:3790
 do_filp_open+0x1f1/0x430 fs/namei.c:3817
page last free stack trace:
 reset_page_owner include/linux/page_owner.h:26 [inline]
 free_pages_prepare mm/page_alloc.c:1551 [inline]
 free_pcp_prepare mm/page_alloc.c:1625 [inline]
 free_unref_page_prepare+0x742/0x750 mm/page_alloc.c:3589
 free_unref_page+0x95/0x540 mm/page_alloc.c:3687
 free_the_page mm/page_alloc.c:836 [inline]
 __free_pages+0x67/0x100 mm/page_alloc.c:5957
 __free_slab+0xca/0x1a0 mm/slub.c:2044
 free_slab mm/slub.c:2059 [inline]
 discard_slab+0x29/0x40 mm/slub.c:2065
 __slab_free+0x201/0x280 mm/slub.c:3625
 do_slab_free mm/slub.c:3666 [inline]
 ___cache_free+0xbf/0xd0 mm/slub.c:3722
 qlink_free mm/kasan/quarantine.c:168 [inline]
 qlist_free_all+0xc6/0x140 mm/kasan/quarantine.c:187
 kasan_quarantine_reduce+0x14a/0x170 mm/kasan/quarantine.c:294
 __kasan_slab_alloc+0x24/0x80 mm/kasan/common.c:311
 kasan_slab_alloc include/linux/kasan.h:202 [inline]
 slab_post_alloc_hook+0x4f/0x2d0 mm/slab.h:768
 slab_alloc_node mm/slub.c:3382 [inline]
 slab_alloc mm/slub.c:3392 [inline]
 __kmem_cache_alloc_lru mm/slub.c:3399 [inline]
 kmem_cache_alloc+0x16e/0x330 mm/slub.c:3408
 getname_flags+0xb9/0x500 fs/namei.c:139
 getname+0x19/0x20 fs/namei.c:218
 do_sys_openat2+0xeb/0x810 fs/open.c:1337
 do_sys_open fs/open.c:1359 [inline]
 __do_sys_openat fs/open.c:1375 [inline]
 __se_sys_openat fs/open.c:1370 [inline]
 __x64_sys_openat+0x136/0x160 fs/open.c:1370

Memory state around the buggy address:
 ffff88814a0caf00: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
 ffff88814a0caf80: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
>ffff88814a0cb000: fa fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
                   ^
 ffff88814a0cb080: fb fb fb fb fb fb fb fb fb fb fc fc fc fc fc fc
 ffff88814a0cb100: fc fc fa fb fb fb fb fb fb fb fb fb fb fb fb fb
==================================================================
------------[ cut here ]------------
WARNING: CPU: 1 PID: 9035 at fs/dcache.c:794 fast_dput+0x210/0x290 fs/dcache.c:794
Modules linked in:
CPU: 1 PID: 9035 Comm: syz-executor Tainted: G    B   W          syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/24/2026
RIP: 0010:fast_dput+0x210/0x290 fs/dcache.c:794
Code: a5 f1 ff e9 46 fe ff ff 89 d9 80 e1 07 80 c1 03 38 c1 0f 8c 99 fe ff ff 48 89 df e8 da a5 f1 ff e9 8c fe ff ff e8 20 78 ac ff <0f> 0b e9 0b ff ff ff 89 d9 80 e1 07 80 c1 03 38 c1 0f 8c e4 fe ff
RSP: 0018:ffffc9000156fad0 EFLAGS: 00010293
RAX: ffffffff81c4f3f0 RBX: ffff88814a0cb000 RCX: ffff88811c0bbcc0
RDX: 0000000000000000 RSI: 00000000ffffff80 RDI: 0000000000000001
RBP: ffffc9000156fb00 R08: 0000000000000003 R09: 0000000000000004
R10: dffffc0000000000 R11: fffff520002adf4c R12: 00000000ffffff80
R13: dffffc0000000000 R14: ffff88814a0cb058 R15: 1ffff1102941960b
FS:  0000000000000000(0000) GS:ffff8881f6f00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007ff5e3be96c0 CR3: 000000000700f000 CR4: 00000000003526a0
Call Trace:
 <TASK>
 dput+0x21/0x80 fs/dcache.c:905
 incfs_free_mount_info+0x60/0x200 fs/incfs/data_mgmt.c:166
 incfs_kill_sb+0x1b8/0x220 fs/incfs/vfs.c:2003
 deactivate_locked_super+0xb5/0x120 fs/super.c:334
 deactivate_super+0xaf/0xe0 fs/super.c:365
 cleanup_mnt+0x474/0x500 fs/namespace.c:1191
 __cleanup_mnt+0x19/0x20 fs/namespace.c:1198
 task_work_run+0x1e1/0x250 kernel/task_work.c:203
 exit_task_work include/linux/task_work.h:39 [inline]
 do_exit+0xa35/0x2660 kernel/exit.c:886
 do_group_exit+0x210/0x2d0 kernel/exit.c:1028
 __do_sys_exit_group kernel/exit.c:1039 [inline]
 __se_sys_exit_group kernel/exit.c:1037 [inline]
 __x64_sys_exit_group+0x3f/0x40 kernel/exit.c:1037
 x64_sys_call+0x7b4/0x9a0 arch/x86/include/generated/asm/syscalls_64.h:232
 do_syscall_x64 arch/x86/entry/common.c:46 [inline]
 do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:76
 entry_SYSCALL_64_after_hwframe+0x68/0xd2
RIP: 0033:0x7fb25939bf79
Code: Unable to access opcode bytes at 0x7fb25939bf4f.
RSP: 002b:00007ffd1928dad8 EFLAGS: 00000246 ORIG_RAX: 00000000000000e7
RAX: ffffffffffffffda RBX: 00007fb259431c9b RCX: 00007fb25939bf79
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000001
RBP: 0000000000000009 R08: 0000000000000000 R09: 00007fb259431c3b
R10: 0000000000000000 R11: 0000000000000246 R12: 00007ffd1928ed90
R13: 00007fb259431c3b R14: 000055555e7b64e8 R15: 00007ffd1928fe60
 </TASK>
---[ end trace 0000000000000000 ]---

Crashes (10):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2026/02/11 16:46 android14-6.1 edbe3e111301 75707236 .config console log report info [disk image] [vmlinux] [kernel image] ci2-android-6-1 KASAN: use-after-free Read in incfs_free_mount_info
2026/02/10 04:17 android14-6.1 c9e2710a7bd0 4ab09a02 .config console log report info [disk image] [vmlinux] [kernel image] ci2-android-6-1 KASAN: use-after-free Read in incfs_free_mount_info
2026/02/09 20:15 android14-6.1 c9e2710a7bd0 df949cd9 .config console log report info [disk image] [vmlinux] [kernel image] ci2-android-6-1 KASAN: use-after-free Read in incfs_free_mount_info
2026/02/09 08:41 android14-6.1 c9e2710a7bd0 4c131dc4 .config console log report info [disk image] [vmlinux] [kernel image] ci2-android-6-1 KASAN: use-after-free Read in incfs_free_mount_info
2026/02/08 07:23 android14-6.1 c9e2710a7bd0 4c131dc4 .config console log report info [disk image] [vmlinux] [kernel image] ci2-android-6-1 KASAN: use-after-free Read in incfs_free_mount_info
2026/02/05 08:38 android14-6.1 775f23d50ca8 ea10c935 .config console log report info [disk image] [vmlinux] [kernel image] ci2-android-6-1 KASAN: use-after-free Read in incfs_free_mount_info
2026/02/02 04:09 android14-6.1 478ca7133d0e 6b8752f2 .config console log report info [disk image] [vmlinux] [kernel image] ci2-android-6-1 KASAN: use-after-free Read in incfs_free_mount_info
2026/01/25 05:28 android14-6.1 f282db65d7e9 40acda8a .config console log report info [disk image] [vmlinux] [kernel image] ci2-android-6-1 KASAN: use-after-free Read in incfs_free_mount_info
2026/01/22 16:24 android14-6.1 c298d33764cb a16aed1d .config console log report info [disk image] [vmlinux] [kernel image] ci2-android-6-1 KASAN: use-after-free Read in incfs_free_mount_info
2026/01/18 22:40 android14-6.1 37a76cbe8f87 20d37d28 .config console log report info [disk image] [vmlinux] [kernel image] ci2-android-6-1 KASAN: use-after-free Read in incfs_free_mount_info
* Struck through repros no longer work on HEAD.