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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 ffff888118f54535 by task syz-executor/455

CPU: 0 PID: 455 Comm: syz-executor Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 08/18/2025
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: 0033:0x7f75085c1873
Code: c1 66 0f 1f 44 00 00 48 83 c4 08 48 89 ef 5b 5d e9 a2 3e 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:00007ffe9a1ad978 EFLAGS: 00000293 ORIG_RAX: 00000000000000d9
RAX: ffffffffffffffda RBX: 0000555555e964e0 RCX: 00007f75085c1873
RDX: 0000000000008000 RSI: 0000555555e964e0 RDI: 0000000000000005
RBP: 0000555555e964b4 R08: 0000000000028b61 R09: 0000000000000000
R10: 00007f750871fca0 R11: 0000000000000293 R12: ffffffffffffffa8
R13: 0000000000000010 R14: 0000555555e964b0 R15: 00007ffe9a1afc20

Allocated by task 465:
 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+0x165/0x2e0 mm/slub.c:2965
 sk_prot_alloc+0x5c/0x340 net/core/sock.c:1712
 sk_alloc+0x38/0x4e0 net/core/sock.c:1779
 unix_create1+0x90/0x5e0 net/unix/af_unix.c:797
 unix_create+0x135/0x1c0 net/unix/af_unix.c:859
 __sock_create+0x38d/0x770 net/socket.c:1436
 sock_create net/socket.c:1487 [inline]
 __sys_socket+0xec/0x190 net/socket.c:1529
 __do_sys_socket net/socket.c:1538 [inline]
 __se_sys_socket net/socket.c:1536 [inline]
 __x64_sys_socket+0x7a/0x90 net/socket.c:1536
 do_syscall_64+0x31/0x40 arch/x86/entry/common.c:46
 entry_SYSCALL_64_after_hwframe+0x61/0xcb

Freed by task 465:
 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
 sk_prot_free net/core/sock.c:1760 [inline]
 __sk_destruct+0x4ad/0x600 net/core/sock.c:1848
 sk_destruct net/core/sock.c:1863 [inline]
 __sk_free+0x313/0x410 net/core/sock.c:1874
 sk_free+0x54/0x90 net/core/sock.c:1885
 sock_put include/net/sock.h:1894 [inline]
 unix_release_sock+0x8ec/0xad0 net/unix/af_unix.c:569
 unix_release+0x4e/0x80 net/unix/af_unix.c:869
 __sock_release net/socket.c:597 [inline]
 sock_close+0xe0/0x270 net/socket.c:1286
 __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
 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

The buggy address belongs to the object at ffff888118f54500
 which belongs to the cache UNIX of size 1152
The buggy address is located 53 bytes inside of
 1152-byte region [ffff888118f54500, ffff888118f54980)
The buggy address belongs to the page:
page:ffffea000463d500 refcount:1 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x118f54
head:ffffea000463d500 order:2 compound_mapcount:0 compound_pincount:0
flags: 0x4000000000010200(slab|head)
raw: 4000000000010200 dead000000000100 dead000000000122 ffff888107fdc300
raw: 0000000000000000 00000000000c000c 00000001ffffffff 0000000000000000
page dumped because: kasan: bad access detected
page_owner tracks the page as allocated
page last allocated via order 2, migratetype Unmovable, gfp_mask 0x1d20c0(__GFP_IO|__GFP_FS|__GFP_NOWARN|__GFP_NORETRY|__GFP_COMP|__GFP_NOMEMALLOC|__GFP_HARDWALL), pid 460, ts 47292454633, free_ts 47289662684
 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+0x1af/0x2e0 mm/slub.c:2965
 sk_prot_alloc+0x5c/0x340 net/core/sock.c:1712
 sk_alloc+0x38/0x4e0 net/core/sock.c:1779
 unix_create1+0x90/0x5e0 net/unix/af_unix.c:797
 unix_create+0x135/0x1c0 net/unix/af_unix.c:859
 __sock_create+0x38d/0x770 net/socket.c:1436
 sock_create net/socket.c:1487 [inline]
 __sys_socket+0xec/0x190 net/socket.c:1529
 __do_sys_socket net/socket.c:1538 [inline]
 __se_sys_socket net/socket.c:1536 [inline]
 __x64_sys_socket+0x7a/0x90 net/socket.c:1536
 do_syscall_64+0x31/0x40 arch/x86/entry/common.c:46
 entry_SYSCALL_64_after_hwframe+0x61/0xcb
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_pages_ok+0x7fc/0x820 mm/page_alloc.c:1629
 free_the_page mm/page_alloc.c:5431 [inline]
 __free_pages+0xdd/0x380 mm/page_alloc.c:5440
 __free_slab+0xcf/0x190 mm/slub.c:1899
 free_slab mm/slub.c:1914 [inline]
 discard_slab mm/slub.c:1920 [inline]
 unfreeze_partials+0x15f/0x190 mm/slub.c:2415
 put_cpu_partial+0xc1/0x180 mm/slub.c:2451
 __slab_free+0x2c9/0x3a0 mm/slub.c:3100
 do_slab_free mm/slub.c:3196 [inline]
 ___cache_free+0x111/0x130 mm/slub.c:3215
 qlink_free+0x50/0x90 mm/kasan/quarantine.c:157
 qlist_free_all+0x5f/0xb0 mm/kasan/quarantine.c:176
 kasan_quarantine_reduce+0x14a/0x160 mm/kasan/quarantine.c:283
 __kasan_slab_alloc+0x2f/0xf0 mm/kasan/common.c:440
 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_trace+0x160/0x2e0 mm/slub.c:2977
 kmalloc include/linux/slab.h:552 [inline]
 kzalloc include/linux/slab.h:664 [inline]
 ____ip_mc_inc_group+0x190/0x820 net/ipv4/igmp.c:1452
 __ip_mc_inc_group net/ipv4/igmp.c:1487 [inline]
 ip_mc_inc_group net/ipv4/igmp.c:1493 [inline]
 ip_mc_up+0x112/0x1f0 net/ipv4/igmp.c:1792
 inetdev_event+0xc13/0x1030 net/ipv4/devinet.c:1587

Memory state around the buggy address:
 ffff888118f54400: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff888118f54480: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
>ffff888118f54500: fa fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
                                     ^
 ffff888118f54580: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff888118f54600: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
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