================================================================== BUG: KASAN: use-after-free in fast_dput+0x1e9/0x290 fs/dcache.c:753 Read of size 4 at addr ffff88812926e880 by task syz-executor/286 CPU: 1 PID: 286 Comm: syz-executor Tainted: G W syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 04/18/2026 Call Trace: __dump_stack+0x21/0x30 lib/dump_stack.c:88 dump_stack_lvl+0x110/0x170 lib/dump_stack.c:106 print_address_description+0x7f/0x2c0 mm/kasan/report.c:248 __kasan_report mm/kasan/report.c:427 [inline] kasan_report+0xf1/0x140 mm/kasan/report.c:444 __asan_report_load4_noabort+0x14/0x20 mm/kasan/report_generic.c:308 fast_dput+0x1e9/0x290 fs/dcache.c:753 dput+0x26/0x90 fs/dcache.c:880 incfs_free_mount_info+0x60/0x200 fs/incfs/data_mgmt.c:166 incfs_kill_sb+0x1b8/0x220 fs/incfs/vfs.c:1997 deactivate_locked_super+0xa0/0x100 fs/super.c:335 deactivate_super+0xaf/0xe0 fs/super.c:366 cleanup_mnt+0x45b/0x510 fs/namespace.c:1148 __cleanup_mnt+0x19/0x20 fs/namespace.c:1155 task_work_run+0x127/0x190 kernel/task_work.c:188 exit_task_work include/linux/task_work.h:33 [inline] do_exit+0xb35/0x2890 kernel/exit.c:890 do_group_exit+0x141/0x310 kernel/exit.c:1004 __do_sys_exit_group kernel/exit.c:1015 [inline] __se_sys_exit_group kernel/exit.c:1013 [inline] __x64_sys_exit_group+0x3f/0x40 kernel/exit.c:1013 x64_sys_call+0x832/0x9a0 arch/x86/include/generated/asm/syscalls_64.h:232 do_syscall_x64 arch/x86/entry/common.c:50 [inline] do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:80 entry_SYSCALL_64_after_hwframe+0x66/0xd0 RIP: 0033:0x7fa9052ebe59 Code: Unable to access opcode bytes at RIP 0x7fa9052ebe2f. RSP: 002b:00007ffc16c9bdb8 EFLAGS: 00000246 ORIG_RAX: 00000000000000e7 RAX: ffffffffffffffda RBX: 00007fa90538122a RCX: 00007fa9052ebe59 RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000001 RBP: 0000000000000009 R08: 0000000000000000 R09: 00007fa9053811ca R10: 0000000000000000 R11: 0000000000000246 R12: 00007ffc16c9d070 R13: 00007fa9053811ca R14: 000055555dfd14e8 R15: 00007ffc16c9e140 Allocated by task 508: 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:433 [inline] __kasan_slab_alloc+0xbd/0xf0 mm/kasan/common.c:466 kasan_slab_alloc include/linux/kasan.h:217 [inline] slab_post_alloc_hook+0x4f/0x2b0 mm/slab.h:550 slab_alloc_node mm/slub.c:3245 [inline] slab_alloc mm/slub.c:3255 [inline] kmem_cache_alloc+0xf7/0x260 mm/slub.c:3260 __d_alloc+0x2d/0x6a0 fs/dcache.c:1749 d_alloc fs/dcache.c:1828 [inline] d_alloc_parallel+0xe2/0x1370 fs/dcache.c:2584 __lookup_slow+0x14c/0x410 fs/namei.c:1656 lookup_one_len+0x19d/0x2d0 fs/namei.c:2726 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:1884 legacy_get_tree+0xed/0x190 fs/fs_context.c:611 vfs_get_tree+0x89/0x260 fs/super.c:1530 do_new_mount+0x25a/0xa20 fs/namespace.c:3034 path_mount+0x659/0xff0 fs/namespace.c:3364 do_mount fs/namespace.c:3377 [inline] __do_sys_mount fs/namespace.c:3585 [inline] __se_sys_mount+0x320/0x390 fs/namespace.c:3562 __x64_sys_mount+0xbf/0xd0 fs/namespace.c:3562 x64_sys_call+0x6bf/0x9a0 arch/x86/include/generated/asm/syscalls_64.h:166 do_syscall_x64 arch/x86/entry/common.c:50 [inline] do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:80 entry_SYSCALL_64_after_hwframe+0x66/0xd0 Freed by task 532: 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:365 __kasan_slab_free+0x11/0x20 mm/kasan/common.c:373 kasan_slab_free include/linux/kasan.h:193 [inline] slab_free_hook mm/slub.c:1728 [inline] slab_free_freelist_hook+0xc2/0x190 mm/slub.c:1754 slab_free mm/slub.c:3526 [inline] kmem_cache_free+0x100/0x320 mm/slub.c:3544 __d_free+0x23/0x30 fs/dcache.c:273 rcu_do_batch+0x532/0xbe0 kernel/rcu/tree.c:2523 rcu_core+0x5ee/0xf80 kernel/rcu/tree.c:2763 rcu_core_si+0x9/0x10 kernel/rcu/tree.c:2776 handle_softirqs+0x250/0x560 kernel/softirq.c:583 __do_softirq kernel/softirq.c:621 [inline] invoke_softirq kernel/softirq.c:443 [inline] __irq_exit_rcu+0x52/0xf0 kernel/softirq.c:670 irq_exit_rcu+0x9/0x10 kernel/softirq.c:682 instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1108 [inline] sysvec_apic_timer_interrupt+0xa9/0xc0 arch/x86/kernel/apic/apic.c:1108 asm_sysvec_apic_timer_interrupt+0x1b/0x20 arch/x86/include/asm/idtentry.h:676 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_common kernel/rcu/tree.c:3011 [inline] call_rcu+0x10b/0xf80 kernel/rcu/tree.c:3129 dentry_free+0xbd/0x150 fs/dcache.c:-1 __dentry_kill+0x50a/0x650 fs/dcache.c:600 dentry_kill+0xc0/0x2a0 fs/dcache.c:-1 dput+0x47/0x90 fs/dcache.c:893 incfs_free_mount_info+0x60/0x200 fs/incfs/data_mgmt.c:166 incfs_kill_sb+0x1b8/0x220 fs/incfs/vfs.c:1997 deactivate_locked_super+0xa0/0x100 fs/super.c:335 deactivate_super+0xaf/0xe0 fs/super.c:366 cleanup_mnt+0x45b/0x510 fs/namespace.c:1148 __cleanup_mnt+0x19/0x20 fs/namespace.c:1155 task_work_run+0x127/0x190 kernel/task_work.c:188 exit_task_work include/linux/task_work.h:33 [inline] do_exit+0xb35/0x2890 kernel/exit.c:890 do_group_exit+0x141/0x310 kernel/exit.c:1004 __do_sys_exit_group kernel/exit.c:1015 [inline] __se_sys_exit_group kernel/exit.c:1013 [inline] __x64_sys_exit_group+0x3f/0x40 kernel/exit.c:1013 x64_sys_call+0x832/0x9a0 arch/x86/include/generated/asm/syscalls_64.h:232 do_syscall_x64 arch/x86/entry/common.c:50 [inline] do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:80 entry_SYSCALL_64_after_hwframe+0x66/0xd0 The buggy address belongs to the object at ffff88812926e880 which belongs to the cache dentry of size 208 The buggy address is located 0 bytes inside of 208-byte region [ffff88812926e880, ffff88812926e950) The buggy address belongs to the page: page:ffffea0004a49b80 refcount:1 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x12926e flags: 0x4000000000000200(slab|zone=1) raw: 4000000000000200 0000000000000000 dead000000000122 ffff8881001c4d80 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 508, ts 29528460923, free_ts 0 set_page_owner include/linux/page_owner.h:33 [inline] post_alloc_hook+0x192/0x1b0 mm/page_alloc.c:2605 prep_new_page+0x1c/0x110 mm/page_alloc.c:2611 get_page_from_freelist+0x2d3a/0x2dc0 mm/page_alloc.c:4485 __alloc_pages+0x1a2/0x460 mm/page_alloc.c:5822 alloc_slab_page mm/slub.c:-1 [inline] allocate_slab mm/slub.c:1937 [inline] new_slab+0xa1/0x4d0 mm/slub.c:2000 ___slab_alloc+0x381/0x810 mm/slub.c:3033 __slab_alloc+0x49/0x90 mm/slub.c:3120 slab_alloc_node mm/slub.c:3211 [inline] slab_alloc mm/slub.c:3255 [inline] kmem_cache_alloc+0x138/0x260 mm/slub.c:3260 __d_alloc+0x2d/0x6a0 fs/dcache.c:1749 d_alloc+0x4b/0x260 fs/dcache.c:1828 lookup_one_qstr_excl+0xcb/0x250 fs/namei.c:1567 filename_create+0x235/0x470 fs/namei.c:3844 do_mkdirat+0x5c/0x4c0 fs/namei.c:4088 __do_sys_mkdir fs/namei.c:4118 [inline] __se_sys_mkdir fs/namei.c:4116 [inline] __x64_sys_mkdir+0x6e/0x80 fs/namei.c:4116 x64_sys_call+0x124/0x9a0 arch/x86/include/generated/asm/syscalls_64.h:84 do_syscall_x64 arch/x86/entry/common.c:50 [inline] do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:80 page_owner free stack trace missing Memory state around the buggy address: ffff88812926e780: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ffff88812926e800: fb fb fb fb fb fb fb fb fc fc fc fc fc fc fc fc >ffff88812926e880: fa fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ^ ffff88812926e900: fb fb fb fb fb fb fb fb fb fb fc fc fc fc fc fc ffff88812926e980: fc fc fa fb fb fb fb fb fb fb fb fb fb fb fb fb ==================================================================