==================================================================
BUG: KASAN: use-after-free in fast_dput+0x1e0/0x290 fs/dcache.c:750
Read of size 4 at addr ffff888131399330 by task syz-executor/800

CPU: 1 PID: 800 Comm: syz-executor Tainted: G        W         syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/24/2026
Call Trace:
 __dump_stack+0x21/0x24 lib/dump_stack.c:77
 dump_stack_lvl+0x1a7/0x208 lib/dump_stack.c:118
 print_address_description+0x7f/0x2c0 mm/kasan/report.c:248
 __kasan_report mm/kasan/report.c:435 [inline]
 kasan_report+0x100/0x140 mm/kasan/report.c:452
 __asan_report_load4_noabort+0x14/0x20 mm/kasan/report_generic.c:308
 fast_dput+0x1e0/0x290 fs/dcache.c:750
 dput+0x21/0x80 fs/dcache.c:870
 incfs_free_mount_info+0x60/0x200 fs/incfs/data_mgmt.c:166
 incfs_kill_sb+0x1a1/0x200 fs/incfs/vfs.c:1979
 deactivate_locked_super+0xa0/0x100 fs/super.c:335
 deactivate_super+0xaf/0xe0 fs/super.c:366
 cleanup_mnt+0x44f/0x500 fs/namespace.c:1123
 __cleanup_mnt+0x19/0x20 fs/namespace.c:1130
 task_work_run+0x127/0x190 kernel/task_work.c:189
 exit_task_work include/linux/task_work.h:33 [inline]
 do_exit+0xa7c/0x24e0 kernel/exit.c:873
 do_group_exit+0x149/0x310 kernel/exit.c:987
 __do_sys_exit_group kernel/exit.c:998 [inline]
 __se_sys_exit_group kernel/exit.c:996 [inline]
 __x64_sys_exit_group+0x3f/0x40 kernel/exit.c:996
 do_syscall_64+0x31/0x40 arch/x86/entry/common.c:46
 entry_SYSCALL_64_after_hwframe+0x61/0xcb
RIP: 0033:0x7f9ccaa300d9
Code: Unable to access opcode bytes at RIP 0x7f9ccaa300af.
RSP: 002b:00007ffda9000bc8 EFLAGS: 00000246 ORIG_RAX: 00000000000000e7
RAX: ffffffffffffffda RBX: 00007f9ccaac6499 RCX: 00007f9ccaa300d9
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000001
RBP: 0000000000000074 R08: 0000000000000000 R09: 00007f9ccaac6474
R10: 0000000000000000 R11: 0000000000000246 R12: 00007ffda9001e80
R13: 00007f9ccaac6474 R14: 000000000000b00b R15: 00007ffda9002f50

Allocated by task 942:
 kasan_save_stack mm/kasan/common.c:38 [inline]
 kasan_set_track mm/kasan/common.c:45 [inline]
 set_alloc_info mm/kasan/common.c:430 [inline]
 __kasan_slab_alloc+0xb7/0xe0 mm/kasan/common.c:463
 kasan_slab_alloc include/linux/kasan.h:244 [inline]
 slab_post_alloc_hook+0x5d/0x2f0 mm/slab.h:580
 slab_alloc_node mm/slub.c:2952 [inline]
 slab_alloc mm/slub.c:2960 [inline]
 kmem_cache_alloc+0x15a/0x2d0 mm/slub.c:2965
 __d_alloc+0x2d/0x690 fs/dcache.c:1714
 d_alloc fs/dcache.c:1793 [inline]
 d_alloc_parallel+0xe2/0x1390 fs/dcache.c:2549
 __lookup_slow+0x14c/0x410 fs/namei.c:1633
 lookup_one_len+0x196/0x2d0 fs/namei.c:2664
 incfs_lookup_dentry+0x60/0xb0 fs/incfs/data_mgmt.c:210
 open_or_create_special_dir+0x4c/0x1e0 fs/incfs/vfs.c:469
 incfs_mount_fs+0x434/0x8d0 fs/incfs/vfs.c:1867
 legacy_get_tree+0xed/0x190 fs/fs_context.c:593
 vfs_get_tree+0x89/0x260 fs/super.c:1572
 do_new_mount+0x25a/0xa30 fs/namespace.c:3006
 path_mount+0x581/0xca0 fs/namespace.c:3336
 do_mount fs/namespace.c:3349 [inline]
 __do_sys_mount fs/namespace.c:3557 [inline]
 __se_sys_mount+0x320/0x390 fs/namespace.c:3534
 __x64_sys_mount+0xbf/0xd0 fs/namespace.c:3534
 do_syscall_64+0x31/0x40 arch/x86/entry/common.c:46
 entry_SYSCALL_64_after_hwframe+0x61/0xcb

Freed by task 19:
 kasan_save_stack mm/kasan/common.c:38 [inline]
 kasan_set_track+0x4a/0x70 mm/kasan/common.c:45
 kasan_set_free_info+0x23/0x40 mm/kasan/generic.c:370
 ____kasan_slab_free+0x125/0x160 mm/kasan/common.c:362
 __kasan_slab_free+0x11/0x20 mm/kasan/common.c:370
 kasan_slab_free include/linux/kasan.h:220 [inline]
 slab_free_hook mm/slub.c:1600 [inline]
 slab_free_freelist_hook+0xc5/0x190 mm/slub.c:1626
 slab_free mm/slub.c:3208 [inline]
 kmem_cache_free+0x100/0x2d0 mm/slub.c:3224
 __d_free+0x23/0x30 fs/dcache.c:271
 rcu_do_batch+0x488/0xaf0 kernel/rcu/tree.c:2494
 rcu_core+0x50a/0xca0 kernel/rcu/tree.c:2735
 rcu_core_si+0x9/0x10 kernel/rcu/tree.c:2748
 __do_softirq+0x255/0x563 kernel/softirq.c:309

Last potentially related work creation:
 kasan_save_stack+0x3a/0x60 mm/kasan/common.c:38
 __kasan_record_aux_stack+0xd2/0x100 mm/kasan/generic.c:348
 kasan_record_aux_stack_noalloc+0xb/0x10 mm/kasan/generic.c:358
 __call_rcu kernel/rcu/tree.c:2980 [inline]
 call_rcu+0x11a/0x1090 kernel/rcu/tree.c:3054
 dentry_free+0xbd/0x150 fs/dcache.c:-1
 __dentry_kill+0x516/0x660 fs/dcache.c:597
 dentry_kill+0xc0/0x2a0 fs/dcache.c:-1
 dput+0x42/0x80 fs/dcache.c:883
 incfs_free_mount_info+0x60/0x200 fs/incfs/data_mgmt.c:166
 incfs_kill_sb+0x1a1/0x200 fs/incfs/vfs.c:1979
 deactivate_locked_super+0xa0/0x100 fs/super.c:335
 deactivate_super+0xaf/0xe0 fs/super.c:366
 cleanup_mnt+0x44f/0x500 fs/namespace.c:1123
 __cleanup_mnt+0x19/0x20 fs/namespace.c:1130
 task_work_run+0x127/0x190 kernel/task_work.c:189
 exit_task_work include/linux/task_work.h:33 [inline]
 do_exit+0xa7c/0x24e0 kernel/exit.c:873
 do_group_exit+0x149/0x310 kernel/exit.c:987
 __do_sys_exit_group kernel/exit.c:998 [inline]
 __se_sys_exit_group kernel/exit.c:996 [inline]
 __x64_sys_exit_group+0x3f/0x40 kernel/exit.c:996
 do_syscall_64+0x31/0x40 arch/x86/entry/common.c:46
 entry_SYSCALL_64_after_hwframe+0x61/0xcb

The buggy address belongs to the object at ffff888131399330
 which belongs to the cache dentry of size 208
The buggy address is located 0 bytes inside of
 208-byte region [ffff888131399330, ffff888131399400)
The buggy address belongs to the page:
page:ffffea0004c4e640 refcount:1 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x131399
flags: 0x4000000000000200(slab)
raw: 4000000000000200 dead000000000100 dead000000000122 ffff88810018b800
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 942, ts 44556466974, free_ts 0
 set_page_owner include/linux/page_owner.h:35 [inline]
 post_alloc_hook mm/page_alloc.c:2456 [inline]
 prep_new_page+0x176/0x190 mm/page_alloc.c:2462
 get_page_from_freelist+0x225f/0x23f0 mm/page_alloc.c:4254
 __alloc_pages_nodemask+0x29a/0x640 mm/page_alloc.c:5384
 alloc_slab_page mm/slub.c:-1 [inline]
 allocate_slab mm/slub.c:1813 [inline]
 new_slab+0x84/0x3f0 mm/slub.c:1874
 new_slab_objects mm/slub.c:2632 [inline]
 ___slab_alloc+0x2f8/0x4c0 mm/slub.c:2796
 __slab_alloc+0x63/0xa0 mm/slub.c:2836
 slab_alloc_node mm/slub.c:2918 [inline]
 slab_alloc mm/slub.c:2960 [inline]
 kmem_cache_alloc+0x1a4/0x2d0 mm/slub.c:2965
 __d_alloc+0x2d/0x690 fs/dcache.c:1714
 d_alloc+0x48/0x260 fs/dcache.c:1793
 __lookup_hash+0xcb/0x250 fs/namei.c:1545
 filename_create+0x1d7/0x680 fs/namei.c:3616
 user_path_create fs/namei.c:3673 [inline]
 do_mkdirat+0x5e/0x340 fs/namei.c:3813
 __do_sys_mkdirat fs/namei.c:3831 [inline]
 __se_sys_mkdirat fs/namei.c:3829 [inline]
 __x64_sys_mkdirat+0x7b/0x90 fs/namei.c:3829
 do_syscall_64+0x31/0x40 arch/x86/entry/common.c:46
 entry_SYSCALL_64_after_hwframe+0x61/0xcb
page_owner free stack trace missing

Memory state around the buggy address:
 ffff888131399200: fc fc fc fc fa fb fb fb fb fb fb fb fb fb fb fb
 ffff888131399280: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fc fc
>ffff888131399300: fc fc fc fc fc fc fa fb fb fb fb fb fb fb fb fb
                                     ^
 ffff888131399380: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff888131399400: fc fc fc fc fc fc fc fc 00 00 00 00 00 00 00 00
==================================================================
------------[ cut here ]------------
WARNING: CPU: 1 PID: 800 at fs/dcache.c:766 fast_dput+0x207/0x290 fs/dcache.c:766
Modules linked in:
CPU: 1 PID: 800 Comm: syz-executor Tainted: G    B   W         syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/24/2026
RIP: 0010:fast_dput+0x207/0x290 fs/dcache.c:766
Code: e0 f2 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 83 e0 f2 ff e9 94 fe ff ff e8 79 6b b8 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:ffffc90002957ba0 EFLAGS: 00010293
RAX: ffffffff81ac3807 RBX: ffff888131399330 RCX: ffff88810fcea780
RDX: 0000000000000000 RSI: 00000000ffffff80 RDI: 0000000000000001
RBP: ffffc90002957bc8 R08: 0000000000000003 R09: 0000000000000004
R10: dffffc0000000000 R11: fffff5200052af64 R12: 00000000ffffff80
R13: dffffc0000000000 R14: ffff888131399388 R15: 1ffff11026273271
FS:  0000000000000000(0000) GS:ffff8881f7100000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f9562753ff8 CR3: 000000011e16c000 CR4: 00000000003526a0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 dput+0x21/0x80 fs/dcache.c:870
 incfs_free_mount_info+0x60/0x200 fs/incfs/data_mgmt.c:166
 incfs_kill_sb+0x1a1/0x200 fs/incfs/vfs.c:1979
 deactivate_locked_super+0xa0/0x100 fs/super.c:335
 deactivate_super+0xaf/0xe0 fs/super.c:366
 cleanup_mnt+0x44f/0x500 fs/namespace.c:1123
 __cleanup_mnt+0x19/0x20 fs/namespace.c:1130
 task_work_run+0x127/0x190 kernel/task_work.c:189
 exit_task_work include/linux/task_work.h:33 [inline]
 do_exit+0xa7c/0x24e0 kernel/exit.c:873
 do_group_exit+0x149/0x310 kernel/exit.c:987
 __do_sys_exit_group kernel/exit.c:998 [inline]
 __se_sys_exit_group kernel/exit.c:996 [inline]
 __x64_sys_exit_group+0x3f/0x40 kernel/exit.c:996
 do_syscall_64+0x31/0x40 arch/x86/entry/common.c:46
 entry_SYSCALL_64_after_hwframe+0x61/0xcb
RIP: 0033:0x7f9ccaa300d9
Code: Unable to access opcode bytes at RIP 0x7f9ccaa300af.
RSP: 002b:00007ffda9000bc8 EFLAGS: 00000246 ORIG_RAX: 00000000000000e7
RAX: ffffffffffffffda RBX: 00007f9ccaac6499 RCX: 00007f9ccaa300d9
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000001
RBP: 0000000000000074 R08: 0000000000000000 R09: 00007f9ccaac6474
R10: 0000000000000000 R11: 0000000000000246 R12: 00007ffda9001e80
R13: 00007f9ccaac6474 R14: 000000000000b00b R15: 00007ffda9002f50
---[ end trace f1ec3d1665691546 ]---