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BUG: KASAN: use-after-free in ext4_htree_fill_tree+0x1066/0x10d0 fs/ext4/namei.c:1221
Read of size 1 at addr ffff888111322a67 by task syz-executor/480

CPU: 0 PID: 480 Comm: syz-executor Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/02/2025
Call Trace:
 __dump_stack+0x21/0x24 lib/dump_stack.c:77
 dump_stack_lvl+0x169/0x1d8 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_load1_noabort+0x14/0x20 mm/kasan/report_generic.c:306
 ext4_htree_fill_tree+0x1066/0x10d0 fs/ext4/namei.c:1221
 ext4_dx_readdir fs/ext4/dir.c:601 [inline]
 ext4_readdir+0x2b45/0x39b0 fs/ext4/dir.c:145
 iterate_dir+0x260/0x570 fs/readdir.c:-1
 __do_sys_getdents64 fs/readdir.c:369 [inline]
 __se_sys_getdents64+0xe5/0x240 fs/readdir.c:354
 __x64_sys_getdents64+0x7b/0x90 fs/readdir.c:354
 do_syscall_64+0x31/0x40 arch/x86/entry/common.c:46
 entry_SYSCALL_64_after_hwframe+0x61/0xcb
RIP: 0033:0x7f2fd7b530d3
Code: c1 66 0f 1f 44 00 00 48 83 c4 08 48 89 ef 5b 5d e9 52 43 f8 ff 66 90 b8 ff ff ff 7f 48 39 c2 48 0f 47 d0 b8 d9 00 00 00 0f 05 <48> 3d 00 f0 ff ff 77 05 c3 0f 1f 40 00 48 c7 c2 a8 ff ff ff f7 d8
RSP: 002b:00007fffb0e44b28 EFLAGS: 00000293 ORIG_RAX: 00000000000000d9
RAX: ffffffffffffffda RBX: 00005555880344e0 RCX: 00007f2fd7b530d3
RDX: 0000000000008000 RSI: 00005555880344e0 RDI: 0000000000000005
RBP: 00005555880344b4 R08: 0000000000028b61 R09: 0000000000000000
R10: 00007f2fd7cadca0 R11: 0000000000000293 R12: ffffffffffffffa8
R13: 0000000000000010 R14: 00005555880344b0 R15: 00007fffb0e46dd0

Allocated by task 440:
 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_kmalloc mm/kasan/common.c:509 [inline]
 __kasan_kmalloc+0xda/0x110 mm/kasan/common.c:518
 kasan_kmalloc include/linux/kasan.h:254 [inline]
 kmem_cache_alloc_trace+0x184/0x2e0 mm/slub.c:2979
 kmalloc include/linux/slab.h:552 [inline]
 kzalloc include/linux/slab.h:664 [inline]
 kobject_uevent_env+0x272/0x700 lib/kobject_uevent.c:539
 kobject_uevent+0x1d/0x30 lib/kobject_uevent.c:657
 netdev_queue_add_kobject net/core/net-sysfs.c:1660 [inline]
 netdev_queue_update_kobjects+0x1a7/0x390 net/core/net-sysfs.c:1694
 register_queue_kobjects net/core/net-sysfs.c:1755 [inline]
 netdev_register_kobject+0x26e/0x320 net/core/net-sysfs.c:2001
 register_netdevice+0xddd/0x13c0 net/core/dev.c:10056
 register_netdev+0x3e/0x50 net/core/dev.c:10180
 loopback_net_init+0x74/0x150 drivers/net/loopback.c:216
 ops_init+0x1ba/0x4a0 net/core/net_namespace.c:144
 setup_net+0x36d/0xb50 net/core/net_namespace.c:345
 copy_net_ns+0x314/0x520 net/core/net_namespace.c:486
 create_new_namespaces+0x3a2/0x650 kernel/nsproxy.c:110
 unshare_nsproxy_namespaces+0x120/0x170 kernel/nsproxy.c:231
 ksys_unshare+0x4ac/0x7d0 kernel/fork.c:3156
 __do_sys_unshare kernel/fork.c:3224 [inline]
 __se_sys_unshare kernel/fork.c:3222 [inline]
 __x64_sys_unshare+0x38/0x40 kernel/fork.c:3222
 do_syscall_64+0x31/0x40 arch/x86/entry/common.c:46
 entry_SYSCALL_64_after_hwframe+0x61/0xcb

Freed by task 440:
 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]
 kfree+0xc0/0x270 mm/slub.c:4196
 kobject_uevent_env+0x34d/0x700 lib/kobject_uevent.c:641
 kobject_uevent+0x1d/0x30 lib/kobject_uevent.c:657
 netdev_queue_add_kobject net/core/net-sysfs.c:1660 [inline]
 netdev_queue_update_kobjects+0x1a7/0x390 net/core/net-sysfs.c:1694
 register_queue_kobjects net/core/net-sysfs.c:1755 [inline]
 netdev_register_kobject+0x26e/0x320 net/core/net-sysfs.c:2001
 register_netdevice+0xddd/0x13c0 net/core/dev.c:10056
 register_netdev+0x3e/0x50 net/core/dev.c:10180
 loopback_net_init+0x74/0x150 drivers/net/loopback.c:216
 ops_init+0x1ba/0x4a0 net/core/net_namespace.c:144
 setup_net+0x36d/0xb50 net/core/net_namespace.c:345
 copy_net_ns+0x314/0x520 net/core/net_namespace.c:486
 create_new_namespaces+0x3a2/0x650 kernel/nsproxy.c:110
 unshare_nsproxy_namespaces+0x120/0x170 kernel/nsproxy.c:231
 ksys_unshare+0x4ac/0x7d0 kernel/fork.c:3156
 __do_sys_unshare kernel/fork.c:3224 [inline]
 __se_sys_unshare kernel/fork.c:3222 [inline]
 __x64_sys_unshare+0x38/0x40 kernel/fork.c:3222
 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 ffff888111322000
 which belongs to the cache kmalloc-4k of size 4096
The buggy address is located 2663 bytes inside of
 4096-byte region [ffff888111322000, ffff888111323000)
The buggy address belongs to the page:
page:ffffea000444c800 refcount:1 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x111320
head:ffffea000444c800 order:3 compound_mapcount:0 compound_pincount:0
flags: 0x4000000000010200(slab|head)
raw: 4000000000010200 dead000000000100 dead000000000122 ffff888100042c00
raw: 0000000000000000 0000000000040004 00000001ffffffff 0000000000000000
page dumped because: kasan: bad access detected
page_owner tracks the page as allocated
page last allocated via order 3, migratetype Unmovable, gfp_mask 0x1d20c0(__GFP_IO|__GFP_FS|__GFP_NOWARN|__GFP_NORETRY|__GFP_COMP|__GFP_NOMEMALLOC|__GFP_HARDWALL), pid 440, ts 45407653428, free_ts 45355863776
 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+0x2235/0x23d0 mm/page_alloc.c:4254
 __alloc_pages_nodemask+0x268/0x5f0 mm/page_alloc.c:5370
 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_trace+0x1b3/0x2e0 mm/slub.c:2977
 kmalloc include/linux/slab.h:552 [inline]
 kzalloc include/linux/slab.h:664 [inline]
 kobject_uevent_env+0x272/0x700 lib/kobject_uevent.c:539
 kobject_uevent+0x1d/0x30 lib/kobject_uevent.c:657
 netdev_queue_add_kobject net/core/net-sysfs.c:1660 [inline]
 netdev_queue_update_kobjects+0x1a7/0x390 net/core/net-sysfs.c:1694
 register_queue_kobjects net/core/net-sysfs.c:1755 [inline]
 netdev_register_kobject+0x26e/0x320 net/core/net-sysfs.c:2001
 register_netdevice+0xddd/0x13c0 net/core/dev.c:10056
 register_netdev+0x3e/0x50 net/core/dev.c:10180
 loopback_net_init+0x74/0x150 drivers/net/loopback.c:216
 ops_init+0x1ba/0x4a0 net/core/net_namespace.c:144
 setup_net+0x36d/0xb50 net/core/net_namespace.c:345
page last free stack trace:
 reset_page_owner include/linux/page_owner.h:28 [inline]
 free_pages_prepare mm/page_alloc.c:1349 [inline]
 free_pcp_prepare mm/page_alloc.c:1421 [inline]
 free_unref_page_prepare+0x2b7/0x2d0 mm/page_alloc.c:3336
 free_unref_page mm/page_alloc.c:3391 [inline]
 free_the_page mm/page_alloc.c:5429 [inline]
 __free_pages+0x14b/0x380 mm/page_alloc.c:5440
 __vunmap+0x84d/0x9d0 mm/vmalloc.c:2307
 __vfree mm/vmalloc.c:2356 [inline]
 vfree+0x61/0x90 mm/vmalloc.c:2387
 kcov_put kernel/kcov.c:408 [inline]
 kcov_close+0x2b/0x50 kernel/kcov.c:510
 __fput+0x2fb/0x770 fs/file_table.c:281
 ____fput+0x15/0x20 fs/file_table.c:314
 task_work_run+0x127/0x190 kernel/task_work.c:189
 exit_task_work include/linux/task_work.h:33 [inline]
 do_exit+0xa4f/0x2480 kernel/exit.c:872
 do_group_exit+0x141/0x310 kernel/exit.c:986
 get_signal+0xf7d/0x12e0 kernel/signal.c:2793
 arch_do_signal_or_restart+0xbf/0x10f0 arch/x86/kernel/signal.c:805
 handle_signal_work kernel/entry/common.c:145 [inline]
 exit_to_user_mode_loop+0xa2/0xe0 kernel/entry/common.c:169
 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

Memory state around the buggy address:
 ffff888111322900: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff888111322980: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
>ffff888111322a00: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
                                                       ^
 ffff888111322a80: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff888111322b00: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
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