================================================================== BUG: KASAN: use-after-free in fast_dput+0x1e9/0x290 fs/dcache.c:750 Read of size 4 at addr ffff888110674aa0 by task syz-executor/5398 CPU: 1 PID: 5398 Comm: syz-executor Tainted: G W syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/12/2026 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+0xe2/0x130 mm/kasan/report.c:452 __asan_report_load4_noabort+0x14/0x20 mm/kasan/report_generic.c:308 fast_dput+0x1e9/0x290 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+0x1aa/0x210 fs/incfs/vfs.c:1979 deactivate_locked_super+0xa0/0x100 fs/super.c:335 deactivate_super+0xaf/0xe0 fs/super.c:366 cleanup_mnt+0x45b/0x510 fs/namespace.c:1123 __cleanup_mnt+0x19/0x20 fs/namespace.c:1130 task_work_run+0x127/0x190 kernel/task_work.c:189 tracehook_notify_resume include/linux/tracehook.h:188 [inline] exit_to_user_mode_loop+0xcb/0xe0 kernel/entry/common.c:172 exit_to_user_mode_prepare+0x76/0xa0 kernel/entry/common.c:199 syscall_exit_to_user_mode+0x1d/0x40 kernel/entry/common.c:274 do_syscall_64+0x3d/0x40 arch/x86/entry/common.c:56 entry_SYSCALL_64_after_hwframe+0x61/0xcb RIP: 0033:0x7f559d0b89d7 Code: a2 c7 05 1c fd 24 00 00 00 00 00 eb 96 e8 e1 12 00 00 90 31 f6 e9 09 00 00 00 66 0f 1f 84 00 00 00 00 00 b8 a6 00 00 00 0f 05 <48> 3d 00 f0 ff ff 77 01 c3 48 c7 c2 e8 ff ff ff f7 d8 64 89 02 b8 RSP: 002b:00007ffff3b7d428 EFLAGS: 00000202 ORIG_RAX: 00000000000000a6 RAX: 0000000000000000 RBX: 0000000000000000 RCX: 00007f559d0b89d7 RDX: 0000000000000000 RSI: 0000000000000009 RDI: 00007ffff3b7d4e0 RBP: 00007ffff3b7d4e0 R08: 00007ffff3b7e4e0 R09: 00000000ffffffff R10: 0000000000000000 R11: 0000000000000202 R12: 00007ffff3b7e570 R13: 00007f559d14d050 R14: 000000000004b0e7 R15: 00007ffff3b7e5b0 Allocated by task 6244: 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+0xbd/0xf0 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+0x162/0x2d0 mm/slub.c:2965 __d_alloc+0x2d/0x6a0 fs/dcache.c:1714 d_alloc fs/dcache.c:1793 [inline] d_alloc_parallel+0xdf/0x1380 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+0x4f/0x1d0 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/0xa20 fs/namespace.c:3006 path_mount+0x585/0xc90 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 6301: 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+0x4ef/0xab0 kernel/rcu/tree.c:2494 rcu_core+0x577/0xd80 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/0x10b0 kernel/rcu/tree.c:3054 dentry_free+0xbd/0x150 fs/dcache.c:-1 __dentry_kill+0x50a/0x650 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+0x1aa/0x210 fs/incfs/vfs.c:1979 deactivate_locked_super+0xa0/0x100 fs/super.c:335 deactivate_super+0xaf/0xe0 fs/super.c:366 cleanup_mnt+0x45b/0x510 fs/namespace.c:1123 __cleanup_mnt+0x19/0x20 fs/namespace.c:1130 task_work_run+0x127/0x190 kernel/task_work.c:189 tracehook_notify_resume include/linux/tracehook.h:188 [inline] exit_to_user_mode_loop+0xcb/0xe0 kernel/entry/common.c:172 exit_to_user_mode_prepare+0x76/0xa0 kernel/entry/common.c:199 syscall_exit_to_user_mode+0x1d/0x40 kernel/entry/common.c:274 do_syscall_64+0x3d/0x40 arch/x86/entry/common.c:56 entry_SYSCALL_64_after_hwframe+0x61/0xcb Second to 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/0x10b0 kernel/rcu/tree.c:3054 dentry_free+0xbd/0x150 fs/dcache.c:-1 __dentry_kill+0x50a/0x650 fs/dcache.c:597 dentry_kill+0xc0/0x2a0 fs/dcache.c:-1 dput+0x42/0x80 fs/dcache.c:883 lookup_fast+0x5af/0x740 fs/namei.c:1614 walk_component+0x80/0x460 fs/namei.c:1956 link_path_walk+0x5b2/0xba0 fs/namei.c:-1 path_openat+0x27c/0x31c0 fs/namei.c:3513 do_filp_open+0x1e2/0x410 fs/namei.c:3544 do_sys_openat2+0x19f/0x750 fs/open.c:1219 do_sys_open fs/open.c:1235 [inline] __do_sys_openat fs/open.c:1251 [inline] __se_sys_openat fs/open.c:1246 [inline] __x64_sys_openat+0x136/0x160 fs/open.c:1246 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 ffff888110674aa0 which belongs to the cache dentry of size 208 The buggy address is located 0 bytes inside of 208-byte region [ffff888110674aa0, ffff888110674b70) The buggy address belongs to the page: page:ffffea0004419d00 refcount:1 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x110674 flags: 0x4000000000000200(slab) raw: 4000000000000200 ffffea000472f100 0000000700000007 ffff88810018bc80 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 102, ts 5487393200, 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+0x179/0x180 mm/page_alloc.c:2462 get_page_from_freelist+0x223b/0x23d0 mm/page_alloc.c:4254 __alloc_pages_nodemask+0x290/0x620 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+0x2a6/0x450 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+0x1ac/0x2d0 mm/slub.c:2965 __d_alloc+0x2d/0x6a0 fs/dcache.c:1714 d_alloc+0x4b/0x260 fs/dcache.c:1793 __lookup_hash+0xcb/0x250 fs/namei.c:1545 do_unlinkat+0x187/0x680 fs/namei.c:4031 __do_sys_unlink fs/namei.c:4090 [inline] __se_sys_unlink fs/namei.c:4088 [inline] __x64_sys_unlink+0x49/0x50 fs/namei.c:4088 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: ffff888110674980: fc fc fa fb fb fb fb fb fb fb fb fb fb fb fb fb ffff888110674a00: fb fb fb fb fb fb fb fb fb fb fb fb fc fc fc fc >ffff888110674a80: fc fc fc fc fa fb fb fb fb fb fb fb fb fb fb fb ^ ffff888110674b00: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fc fc ffff888110674b80: fc fc fc fc fc fc fa fb fb fb fb fb fb fb fb fb ================================================================== ------------[ cut here ]------------ WARNING: CPU: 1 PID: 5398 at fs/dcache.c:766 fast_dput+0x210/0x290 fs/dcache.c:766 Modules linked in: CPU: 1 PID: 5398 Comm: syz-executor Tainted: G B W syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/12/2026 RIP: 0010:fast_dput+0x210/0x290 fs/dcache.c:766 Code: d5 f2 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 8a d5 f2 ff e9 8c fe ff ff e8 80 55 b8 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:ffffc90001a1fce8 EFLAGS: 00010293 RAX: ffffffff81ac5dd0 RBX: ffff888110674aa0 RCX: ffff888119e28000 RDX: 0000000000000000 RSI: 00000000ffffff80 RDI: 0000000000000001 RBP: ffffc90001a1fd18 R08: 0000000000000003 R09: 0000000000000004 R10: dffffc0000000000 R11: fffff52000343f8c R12: 00000000ffffff80 R13: dffffc0000000000 R14: ffff888110674af8 R15: 1ffff110220ce95f FS: 000055557461e500(0000) GS:ffff8881f7100000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 000000110c2bf346 CR3: 0000000112545000 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+0x1aa/0x210 fs/incfs/vfs.c:1979 deactivate_locked_super+0xa0/0x100 fs/super.c:335 deactivate_super+0xaf/0xe0 fs/super.c:366 cleanup_mnt+0x45b/0x510 fs/namespace.c:1123 __cleanup_mnt+0x19/0x20 fs/namespace.c:1130 task_work_run+0x127/0x190 kernel/task_work.c:189 tracehook_notify_resume include/linux/tracehook.h:188 [inline] exit_to_user_mode_loop+0xcb/0xe0 kernel/entry/common.c:172 exit_to_user_mode_prepare+0x76/0xa0 kernel/entry/common.c:199 syscall_exit_to_user_mode+0x1d/0x40 kernel/entry/common.c:274 do_syscall_64+0x3d/0x40 arch/x86/entry/common.c:56 entry_SYSCALL_64_after_hwframe+0x61/0xcb RIP: 0033:0x7f559d0b89d7 Code: a2 c7 05 1c fd 24 00 00 00 00 00 eb 96 e8 e1 12 00 00 90 31 f6 e9 09 00 00 00 66 0f 1f 84 00 00 00 00 00 b8 a6 00 00 00 0f 05 <48> 3d 00 f0 ff ff 77 01 c3 48 c7 c2 e8 ff ff ff f7 d8 64 89 02 b8 RSP: 002b:00007ffff3b7d428 EFLAGS: 00000202 ORIG_RAX: 00000000000000a6 RAX: 0000000000000000 RBX: 0000000000000000 RCX: 00007f559d0b89d7 RDX: 0000000000000000 RSI: 0000000000000009 RDI: 00007ffff3b7d4e0 RBP: 00007ffff3b7d4e0 R08: 00007ffff3b7e4e0 R09: 00000000ffffffff R10: 0000000000000000 R11: 0000000000000202 R12: 00007ffff3b7e570 R13: 00007f559d14d050 R14: 000000000004b0e7 R15: 00007ffff3b7e5b0 ---[ end trace 5247f07f3ce2f191 ]--- BUG: kernel NULL pointer dereference, address: 0000000000000000 #PF: supervisor instruction fetch in kernel mode #PF: error_code(0x0010) - not-present page PGD 13adde067 P4D 13adde067 PUD 0 Oops: 0010 [#1] PREEMPT SMP KASAN CPU: 0 PID: 5398 Comm: syz-executor Tainted: G B W syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/12/2026 RIP: 0010:0x0 Code: Unable to access opcode bytes at RIP 0xffffffffffffffd6. RSP: 0018:ffffc90001a1fc88 EFLAGS: 00010246 RAX: 1ffffffff0a5297f RBX: ffff888110674550 RCX: 0000000000000282 RDX: 0000000000000000 RSI: 0000000000000008 RDI: ffff888110674550 RBP: ffffc90001a1fcd8 R08: 0000000000000003 R09: fffffffffffffffb R10: dffffc0000000000 R11: ffffed10220ce8b5 R12: 1ffff110220ce8aa R13: dffffc0000000000 R14: ffffffff85294bf8 R15: ffff8881106745a8 FS: 000055557461e500(0000) GS:ffff8881f7000000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: ffffffffffffffd6 CR3: 0000000112545000 CR4: 00000000003526b0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 Call Trace: __dentry_kill+0xca/0x650 fs/dcache.c:571 dentry_kill+0xc0/0x2a0 fs/dcache.c:-1 dput+0x42/0x80 fs/dcache.c:883 incfs_free_mount_info+0x80/0x200 fs/incfs/data_mgmt.c:167 incfs_kill_sb+0x1aa/0x210 fs/incfs/vfs.c:1979 deactivate_locked_super+0xa0/0x100 fs/super.c:335 deactivate_super+0xaf/0xe0 fs/super.c:366 cleanup_mnt+0x45b/0x510 fs/namespace.c:1123 __cleanup_mnt+0x19/0x20 fs/namespace.c:1130 task_work_run+0x127/0x190 kernel/task_work.c:189 tracehook_notify_resume include/linux/tracehook.h:188 [inline] exit_to_user_mode_loop+0xcb/0xe0 kernel/entry/common.c:172 exit_to_user_mode_prepare+0x76/0xa0 kernel/entry/common.c:199 syscall_exit_to_user_mode+0x1d/0x40 kernel/entry/common.c:274 do_syscall_64+0x3d/0x40 arch/x86/entry/common.c:56 entry_SYSCALL_64_after_hwframe+0x61/0xcb RIP: 0033:0x7f559d0b89d7 Code: a2 c7 05 1c fd 24 00 00 00 00 00 eb 96 e8 e1 12 00 00 90 31 f6 e9 09 00 00 00 66 0f 1f 84 00 00 00 00 00 b8 a6 00 00 00 0f 05 <48> 3d 00 f0 ff ff 77 01 c3 48 c7 c2 e8 ff ff ff f7 d8 64 89 02 b8 RSP: 002b:00007ffff3b7d428 EFLAGS: 00000202 ORIG_RAX: 00000000000000a6 RAX: 0000000000000000 RBX: 0000000000000000 RCX: 00007f559d0b89d7 RDX: 0000000000000000 RSI: 0000000000000009 RDI: 00007ffff3b7d4e0 RBP: 00007ffff3b7d4e0 R08: 00007ffff3b7e4e0 R09: 00000000ffffffff R10: 0000000000000000 R11: 0000000000000202 R12: 00007ffff3b7e570 R13: 00007f559d14d050 R14: 000000000004b0e7 R15: 00007ffff3b7e5b0 Modules linked in: CR2: 0000000000000000 ---[ end trace 5247f07f3ce2f192 ]--- RIP: 0010:0x0 Code: Unable to access opcode bytes at RIP 0xffffffffffffffd6. RSP: 0018:ffffc90001a1fc88 EFLAGS: 00010246 RAX: 1ffffffff0a5297f RBX: ffff888110674550 RCX: 0000000000000282 RDX: 0000000000000000 RSI: 0000000000000008 RDI: ffff888110674550 RBP: ffffc90001a1fcd8 R08: 0000000000000003 R09: fffffffffffffffb R10: dffffc0000000000 R11: ffffed10220ce8b5 R12: 1ffff110220ce8aa R13: dffffc0000000000 R14: ffffffff85294bf8 R15: ffff8881106745a8 FS: 000055557461e500(0000) GS:ffff8881f7000000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: ffffffffffffffd6 CR3: 0000000112545000 CR4: 00000000003526b0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400