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EXT4-fs warning (device loop0): dx_probe:861: inode #2: comm syz.0.17: dx entry: limit 65535 != root limit 120
EXT4-fs warning (device loop0): dx_probe:934: inode #2: comm syz.0.17: Corrupt directory, running e2fsck is recommended
==================================================================
BUG: KASAN: slab-use-after-free in __ext4_check_dir_entry+0x755/0x8e0 fs/ext4/dir.c:85
Read of size 2 at addr ffff8880343bb003 by task syz.0.17/6042

CPU: 0 UID: 0 PID: 6042 Comm: syz.0.17 Not tainted syzkaller #0 PREEMPT_{RT,(full)} 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/25/2025
Call Trace:
 <TASK>
 dump_stack_lvl+0xe8/0x150 lib/dump_stack.c:120
 print_address_description mm/kasan/report.c:378 [inline]
 print_report+0xba/0x230 mm/kasan/report.c:482
 kasan_report+0x117/0x150 mm/kasan/report.c:595
 __ext4_check_dir_entry+0x755/0x8e0 fs/ext4/dir.c:85
 ext4_readdir+0x14ac/0x4000 fs/ext4/dir.c:262
 iterate_dir+0x3a5/0x580 fs/readdir.c:108
 __do_sys_getdents64 fs/readdir.c:410 [inline]
 __se_sys_getdents64+0xf1/0x280 fs/readdir.c:396
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xe2/0xf80 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f344625acb9
Code: ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 44 00 00 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 e8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007ffc705c24c8 EFLAGS: 00000246 ORIG_RAX: 00000000000000d9
RAX: ffffffffffffffda RBX: 00007f34464d5fa0 RCX: 00007f344625acb9
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000004
RBP: 00007f34462c8bf7 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f34464d5fac R14: 00007f34464d5fa0 R15: 00007f34464d5fa0
 </TASK>

Allocated by task 5824:
 kasan_save_stack mm/kasan/common.c:57 [inline]
 kasan_save_track+0x3e/0x80 mm/kasan/common.c:78
 unpoison_slab_object mm/kasan/common.c:340 [inline]
 __kasan_slab_alloc+0x6c/0x80 mm/kasan/common.c:366
 kasan_slab_alloc include/linux/kasan.h:253 [inline]
 slab_post_alloc_hook mm/slub.c:4953 [inline]
 slab_alloc_node mm/slub.c:5263 [inline]
 kmem_cache_alloc_noprof+0x188/0x6a0 mm/slub.c:5270
 __kernfs_new_node+0xe9/0x960 fs/kernfs/dir.c:637
 kernfs_new_node+0x102/0x210 fs/kernfs/dir.c:718
 __kernfs_create_file+0x4b/0x2e0 fs/kernfs/file.c:1057
 sysfs_add_file_mode_ns+0x238/0x300 fs/sysfs/file.c:313
 sysfs_merge_group+0x183/0x320 fs/sysfs/group.c:382
 dpm_sysfs_add+0xd2/0x270 drivers/base/power/sysfs.c:704
 device_add+0x4d8/0xb80 drivers/base/core.c:3649
 netdev_register_kobject+0x178/0x310 net/core/net-sysfs.c:2358
 register_netdevice+0x1272/0x1ab0 net/core/dev.c:11406
 register_netdev+0x40/0x60 net/core/dev.c:11522
 vti6_init_net+0x238/0x370 net/ipv6/ip6_vti.c:1158
 ops_init+0x35c/0x5c0 net/core/net_namespace.c:137
 setup_net+0x118/0x340 net/core/net_namespace.c:446
 copy_net_ns+0x3e2/0x570 net/core/net_namespace.c:581
 create_new_namespaces+0x3e7/0x6a0 kernel/nsproxy.c:130
 unshare_nsproxy_namespaces+0x11a/0x160 kernel/nsproxy.c:226
 ksys_unshare+0x4f4/0x900 kernel/fork.c:3171
 __do_sys_unshare kernel/fork.c:3242 [inline]
 __se_sys_unshare kernel/fork.c:3240 [inline]
 __x64_sys_unshare+0x38/0x50 kernel/fork.c:3240
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xe2/0xf80 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

Freed by task 28:
 kasan_save_stack mm/kasan/common.c:57 [inline]
 kasan_save_track+0x3e/0x80 mm/kasan/common.c:78
 kasan_save_free_info+0x46/0x50 mm/kasan/generic.c:584
 poison_slab_object mm/kasan/common.c:253 [inline]
 __kasan_slab_free+0x5c/0x80 mm/kasan/common.c:285
 kasan_slab_free include/linux/kasan.h:235 [inline]
 slab_free_hook mm/slub.c:2540 [inline]
 slab_free mm/slub.c:6670 [inline]
 kmem_cache_free+0x18d/0x8c0 mm/slub.c:6781
 rcu_do_batch kernel/rcu/tree.c:2605 [inline]
 rcu_core kernel/rcu/tree.c:2857 [inline]
 rcu_cpu_kthread+0xbba/0x1b10 kernel/rcu/tree.c:2945
 smpboot_thread_fn+0x541/0xa50 kernel/smpboot.c:160
 kthread+0x726/0x8b0 kernel/kthread.c:463
 ret_from_fork+0x51b/0xa40 arch/x86/kernel/process.c:158
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:246

Last potentially related work creation:
 kasan_save_stack+0x3e/0x60 mm/kasan/common.c:57
 kasan_record_aux_stack+0xbd/0xd0 mm/kasan/generic.c:556
 __call_rcu_common kernel/rcu/tree.c:3119 [inline]
 call_rcu+0xee/0x890 kernel/rcu/tree.c:3239
 kernfs_put+0x191/0x470 fs/kernfs/dir.c:591
 kernfs_remove_by_name_ns+0xb7/0x130 fs/kernfs/dir.c:1723
 kernfs_remove_by_name include/linux/kernfs.h:633 [inline]
 sysfs_unmerge_group+0xd4/0x140 fs/sysfs/group.c:408
 rpm_sysfs_remove drivers/base/power/sysfs.c:823 [inline]
 dpm_sysfs_remove+0x76/0xd0 drivers/base/power/sysfs.c:832
 device_del+0x250/0x900 drivers/base/core.c:3853
 unregister_netdevice_many_notify+0x1dfa/0x2360 net/core/dev.c:12431
 ops_exit_rtnl_list net/core/net_namespace.c:187 [inline]
 ops_undo_list+0x3d3/0x940 net/core/net_namespace.c:248
 cleanup_net+0x4e5/0x7b0 net/core/net_namespace.c:696
 process_one_work kernel/workqueue.c:3257 [inline]
 process_scheduled_works+0xaec/0x17a0 kernel/workqueue.c:3340
 worker_thread+0x89f/0xd90 kernel/workqueue.c:3421
 kthread+0x726/0x8b0 kernel/kthread.c:463
 ret_from_fork+0x51b/0xa40 arch/x86/kernel/process.c:158
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:246

The buggy address belongs to the object at ffff8880343bb000
 which belongs to the cache kernfs_node_cache of size 176
The buggy address is located 3 bytes inside of
 freed 176-byte region [ffff8880343bb000, ffff8880343bb0b0)

The buggy address belongs to the physical page:
page: refcount:0 mapcount:0 mapping:0000000000000000 index:0xffff8880343bb3c0 pfn:0x343bb
flags: 0x80000000000200(workingset|node=0|zone=1)
page_type: f5(slab)
raw: 0080000000000200 ffff88814040b000 ffffea0000bfa4d0 ffffea00009017d0
raw: ffff8880343bb3c0 0000000000110002 00000000f5000000 0000000000000000
page dumped because: kasan: bad access detected
page_owner tracks the page as allocated
page last allocated via order 0, migratetype Unmovable, gfp_mask 0x52cc0(GFP_KERNEL|__GFP_NOWARN|__GFP_NORETRY|__GFP_COMP), pid 5824, tgid 5824 (syz-executor), ts 89728002543, free_ts 72535029384
 set_page_owner include/linux/page_owner.h:32 [inline]
 post_alloc_hook+0x228/0x280 mm/page_alloc.c:1884
 prep_new_page mm/page_alloc.c:1892 [inline]
 get_page_from_freelist+0x28bb/0x2950 mm/page_alloc.c:3945
 __alloc_frozen_pages_noprof+0x18d/0x380 mm/page_alloc.c:5240
 alloc_pages_mpol+0xd1/0x380 mm/mempolicy.c:2486
 alloc_slab_page mm/slub.c:3075 [inline]
 allocate_slab+0x86/0x3a0 mm/slub.c:3248
 new_slab mm/slub.c:3302 [inline]
 ___slab_alloc+0xaf8/0x13d0 mm/slub.c:4656
 __slab_alloc+0xc5/0x1f0 mm/slub.c:4779
 __slab_alloc_node mm/slub.c:4855 [inline]
 slab_alloc_node mm/slub.c:5251 [inline]
 kmem_cache_alloc_noprof+0x100/0x6a0 mm/slub.c:5270
 __kernfs_new_node+0xe9/0x960 fs/kernfs/dir.c:637
 kernfs_new_node+0x102/0x210 fs/kernfs/dir.c:718
 __kernfs_create_file+0x4b/0x2e0 fs/kernfs/file.c:1057
 sysfs_add_file_mode_ns+0x238/0x300 fs/sysfs/file.c:313
 sysfs_merge_group+0x183/0x320 fs/sysfs/group.c:382
 dpm_sysfs_add+0xd2/0x270 drivers/base/power/sysfs.c:704
 device_add+0x4d8/0xb80 drivers/base/core.c:3649
 netdev_register_kobject+0x178/0x310 net/core/net-sysfs.c:2358
page last free pid 5786 tgid 5786 stack trace:
 reset_page_owner include/linux/page_owner.h:25 [inline]
 free_pages_prepare mm/page_alloc.c:1433 [inline]
 __free_frozen_pages+0xfc1/0x1130 mm/page_alloc.c:2973
 __slab_free+0x2e6/0x330 mm/slub.c:6004
 qlink_free mm/kasan/quarantine.c:163 [inline]
 qlist_free_all+0x97/0x100 mm/kasan/quarantine.c:179
 kasan_quarantine_reduce+0x148/0x160 mm/kasan/quarantine.c:286
 __kasan_slab_alloc+0x22/0x80 mm/kasan/common.c:350
 kasan_slab_alloc include/linux/kasan.h:253 [inline]
 slab_post_alloc_hook mm/slub.c:4953 [inline]
 slab_alloc_node mm/slub.c:5263 [inline]
 kmem_cache_alloc_noprof+0x188/0x6a0 mm/slub.c:5270
 getname_flags+0xb7/0x540 fs/namei.c:146
 getname include/linux/fs.h:2498 [inline]
 do_sys_openat2+0xca/0x220 fs/open.c:1426
 do_sys_open fs/open.c:1436 [inline]
 __do_sys_openat fs/open.c:1452 [inline]
 __se_sys_openat fs/open.c:1447 [inline]
 __x64_sys_openat+0x138/0x170 fs/open.c:1447
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xe2/0xf80 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

Memory state around the buggy address:
 ffff8880343baf00: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
 ffff8880343baf80: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
>ffff8880343bb000: fa fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
                   ^
 ffff8880343bb080: fb fb fb fb fb fb fc fc fc fc fc fc fc fc fa fb
 ffff8880343bb100: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
==================================================================