syzbot

R10: 0000000000000000 R11: 0000000000000206 R12: 0000000000000000
R13: 00007f8efd026038 R14: 00007f8efd025fa0 R15: 00007fff12182c48
 </TASK>
---[ end trace 0000000000000000 ]---
==================================================================
BUG: KASAN: use-after-free in fast_dput+0x1e0/0x290 fs/dcache.c:778
Read of size 4 at addr ffff888117ca7aa0 by task syz.4.488/2387

CPU: 0 PID: 2387 Comm: syz.4.488 Tainted: G        W          syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/09/2026
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+0x1e0/0x290 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+0x1af/0x210 fs/incfs/vfs.c:2003
 deactivate_locked_super+0xb5/0x120 fs/super.c:336
 deactivate_super+0xaf/0xe0 fs/super.c:367
 cleanup_mnt+0x45e/0x4e0 fs/namespace.c:1192
 __cleanup_mnt+0x19/0x20 fs/namespace.c:1199
 task_work_run+0x1e1/0x250 kernel/task_work.c:203
 exit_task_work include/linux/task_work.h:39 [inline]
 do_exit+0xaf2/0x2850 kernel/exit.c:887
 do_group_exit+0x21b/0x2e0 kernel/exit.c:1030
 get_signal+0x1382/0x14f0 kernel/signal.c:2891
 arch_do_signal_or_restart+0xd1/0x11c0 arch/x86/kernel/signal.c:871
 exit_to_user_mode_loop+0x7a/0xb0 kernel/entry/common.c:174
 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
 ret_from_fork+0x15/0x30 arch/x86/entry/entry_64.S:288
RIP: 0033:0x7f8efcd9de59
Code: Unable to access opcode bytes at 0x7f8efcd9de2f.
RSP: 002b:00007f8efdc58fd8 EFLAGS: 00000206 ORIG_RAX: 0000000000000038
RAX: 0000000000000000 RBX: 00007f8efd025fa0 RCX: 00007f8efcd9de59
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000011
RBP: 00007f8efce33e6f R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000206 R12: 0000000000000000
R13: 00007f8efd026038 R14: 00007f8efd025fa0 R15: 00007fff12182c48
 </TASK>

Allocated by task 2435:
 kasan_save_stack mm/kasan/common.c:46 [inline]
 kasan_set_track+0x4b/0x70 mm/kasan/common.c:53
 kasan_save_alloc_info+0x1f/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+0x34/0x6d0 fs/dcache.c:1774
 d_alloc fs/dcache.c:1854 [inline]
 d_alloc_parallel+0xe2/0x1280 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+0x4c/0x1f0 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:1578
 do_new_mount+0x251/0xb40 fs/namespace.c:3081
 path_mount+0x640/0xfd0 fs/namespace.c:3411
 do_mount fs/namespace.c:3424 [inline]
 __do_sys_mount fs/namespace.c:3632 [inline]
 __se_sys_mount+0x320/0x390 fs/namespace.c:3609
 __x64_sys_mount+0xbf/0xd0 fs/namespace.c:3609
 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 2370:
 kasan_save_stack mm/kasan/common.c:46 [inline]
 kasan_set_track+0x4b/0x70 mm/kasan/common.c:53
 kasan_save_free_info+0x2b/0x40 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+0x52b/0xc30 kernel/rcu/tree.c:2297
 rcu_core+0x486/0xf00 kernel/rcu/tree.c:2557
 rcu_core_si+0x9/0x10 kernel/rcu/tree.c:2574
 handle_softirqs+0x1d7/0x600 kernel/softirq.c:642
 __do_softirq kernel/softirq.c:680 [inline]
 invoke_softirq kernel/softirq.c:497 [inline]
 __irq_exit_rcu+0x52/0xf0 kernel/softirq.c:729
 irq_exit_rcu+0x9/0x10 kernel/softirq.c:741
 instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1118 [inline]
 sysvec_apic_timer_interrupt+0xa9/0xc0 arch/x86/kernel/apic/apic.c:1118
 asm_sysvec_apic_timer_interrupt+0x1b/0x20 arch/x86/include/asm/idtentry.h:691

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/0xf50 kernel/rcu/tree.c:2926
 dentry_free+0xbd/0x150 fs/dcache.c:-1
 __dentry_kill+0x535/0x680 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+0x1af/0x210 fs/incfs/vfs.c:2003
 deactivate_locked_super+0xb5/0x120 fs/super.c:336
 deactivate_super+0xaf/0xe0 fs/super.c:367
 cleanup_mnt+0x45e/0x4e0 fs/namespace.c:1192
 __cleanup_mnt+0x19/0x20 fs/namespace.c:1199
 task_work_run+0x1e1/0x250 kernel/task_work.c:203
 exit_task_work include/linux/task_work.h:39 [inline]
 do_exit+0xaf2/0x2850 kernel/exit.c:887
 do_group_exit+0x21b/0x2e0 kernel/exit.c:1030
 get_signal+0x1382/0x14f0 kernel/signal.c:2891
 arch_do_signal_or_restart+0xd1/0x11c0 arch/x86/kernel/signal.c:871
 exit_to_user_mode_loop+0x7a/0xb0 kernel/entry/common.c:174
 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
 ret_from_fork+0x15/0x30 arch/x86/entry/entry_64.S:288

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/0xf50 kernel/rcu/tree.c:2926
 dentry_free+0xbd/0x150 fs/dcache.c:-1
 __dentry_kill+0x535/0x680 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+0x66/0x480 fs/super.c:477
 kill_block_super+0x7f/0xf0 fs/super.c:1475
 kill_f2fs_super+0x310/0x3d0 fs/f2fs/super.c:4893
 deactivate_locked_super+0xb5/0x120 fs/super.c:336
 deactivate_super+0xaf/0xe0 fs/super.c:367
 cleanup_mnt+0x45e/0x4e0 fs/namespace.c:1192
 __cleanup_mnt+0x19/0x20 fs/namespace.c:1199
 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 ffff888117ca7aa0
 which belongs to the cache dentry of size 208
The buggy address is located 0 bytes inside of
 208-byte region [ffff888117ca7aa0, ffff888117ca7b70)

The buggy address belongs to the physical page:
page:ffffea00045f29c0 refcount:1 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x117ca7
flags: 0x4000000000000200(slab|zone=1)
raw: 4000000000000200 ffffea00045f6ec0 dead000000000003 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 0x12cd0(GFP_KERNEL|__GFP_NOWARN|__GFP_NORETRY|__GFP_RECLAIMABLE), pid 108, tgid 108 (udevd), ts 4729505812, free_ts 0
 set_page_owner include/linux/page_owner.h:33 [inline]
 post_alloc_hook+0x1f5/0x210 mm/page_alloc.c:2672
 prep_new_page+0x1c/0x110 mm/page_alloc.c:2679
 get_page_from_freelist+0x2ca9/0x2d20 mm/page_alloc.c:4586
 __alloc_pages+0x1fa/0x610 mm/page_alloc.c:5930
 alloc_slab_page+0x6e/0xf0 include/linux/gfp.h:-1
 allocate_slab mm/slub.c:1967 [inline]
 new_slab+0x98/0x3e0 mm/slub.c:2020
 ___slab_alloc+0x70f/0xb70 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+0x34/0x6d0 fs/dcache.c:1774
 d_alloc fs/dcache.c:1854 [inline]
 d_alloc_parallel+0xe2/0x1280 fs/dcache.c:2647
 lookup_open fs/namei.c:3414 [inline]
 open_last_lookups fs/namei.c:3557 [inline]
 path_openat+0x95c/0x2f30 fs/namei.c:3787
 do_filp_open+0x1ee/0x420 fs/namei.c:3817
 do_sys_openat2+0x15e/0x820 fs/open.c:1343
 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
 x64_sys_call+0x783/0x9a0 arch/x86/include/generated/asm/syscalls_64.h:258
page_owner free stack trace missing

Memory state around the buggy address:
 ffff888117ca7980: fc fc 00 00 00 00 00 00 00 00 00 00 00 00 00 00
 ffff888117ca7a00: 00 00 00 00 00 00 00 00 00 00 00 00 fc fc fc fc
>ffff888117ca7a80: fc fc fc fc fa fb fb fb fb fb fb fb fb fb fb fb
                               ^
 ffff888117ca7b00: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fc fc
 ffff888117ca7b80: fc fc fc fc fc fc 00 00 00 00 00 00 00 00 00 00
==================================================================
------------[ cut here ]------------
WARNING: CPU: 0 PID: 2387 at fs/dcache.c:794 fast_dput+0x207/0x290 fs/dcache.c:794
Modules linked in:
CPU: 0 PID: 2387 Comm: syz.4.488 Tainted: G    B   W          syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/09/2026
RIP: 0010:fast_dput+0x207/0x290 fs/dcache.c:794
Code: a4 f1 ff e9 4e fe ff ff 89 d9 80 e1 07 80 c1 03 38 c1 0f 8c a1 fe ff ff 48 89 df e8 53 a4 f1 ff e9 94 fe ff ff e8 c9 19 ac ff <0f> 0b e9 13 ff ff ff 89 d9 80 e1 07 80 c1 03 38 c1 0f 8c ec fe ff
RSP: 0018:ffffc9000828f7f0 EFLAGS: 00010293
RAX: ffffffff81c54a67 RBX: ffff888117ca7aa0 RCX: ffff88811cc13cc0
RDX: 0000000000000000 RSI: 00000000ffffff80 RDI: 0000000000000001
RBP: ffffc9000828f818 R08: 0000000000000003 R09: 0000000000000004
R10: dffffc0000000000 R11: fffff52001051ef0 R12: 00000000ffffff80
R13: dffffc0000000000 R14: ffff888117ca7af8 R15: 1ffff11022f94f5f
FS:  0000000000000000(0000) GS:ffff8881f6e00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f631df58060 CR3: 0000000136401000 CR4: 00000000003526b0
DR0: 0000000000000000 DR1: 0000000000000400 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 0000000000000400
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+0x1af/0x210 fs/incfs/vfs.c:2003
 deactivate_locked_super+0xb5/0x120 fs/super.c:336
 deactivate_super+0xaf/0xe0 fs/super.c:367
 cleanup_mnt+0x45e/0x4e0 fs/namespace.c:1192
 __cleanup_mnt+0x19/0x20 fs/namespace.c:1199
 task_work_run+0x1e1/0x250 kernel/task_work.c:203
 exit_task_work include/linux/task_work.h:39 [inline]
 do_exit+0xaf2/0x2850 kernel/exit.c:887
 do_group_exit+0x21b/0x2e0 kernel/exit.c:1030
 get_signal+0x1382/0x14f0 kernel/signal.c:2891
 arch_do_signal_or_restart+0xd1/0x11c0 arch/x86/kernel/signal.c:871
 exit_to_user_mode_loop+0x7a/0xb0 kernel/entry/common.c:174
 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
 ret_from_fork+0x15/0x30 arch/x86/entry/entry_64.S:288
RIP: 0033:0x7f8efcd9de59
Code: Unable to access opcode bytes at 0x7f8efcd9de2f.
RSP: 002b:00007f8efdc58fd8 EFLAGS: 00000206 ORIG_RAX: 0000000000000038
RAX: 0000000000000000 RBX: 00007f8efd025fa0 RCX: 00007f8efcd9de59
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000011
RBP: 00007f8efce33e6f R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000206 R12: 0000000000000000
R13: 00007f8efd026038 R14: 00007f8efd025fa0 R15: 00007fff12182c48
 </TASK>
---[ end trace 0000000000000000 ]---