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BUG: KASAN: use-after-free in ext4_insert_dentry+0x392/0x710 fs/ext4/namei.c:2117
Write of size 250 at addr ffff88812cb76f18 by task syz.0.54/587

CPU: 0 PID: 587 Comm: syz.0.54 Not tainted 5.10.226-syzkaller-00031-gb14940b90491 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 09/13/2024
Call Trace:
 __dump_stack lib/dump_stack.c:77 [inline]
 dump_stack_lvl+0x1e2/0x24b lib/dump_stack.c:118
 print_address_description+0x81/0x3b0 mm/kasan/report.c:248
 __kasan_report mm/kasan/report.c:435 [inline]
 kasan_report+0x179/0x1c0 mm/kasan/report.c:452
 kasan_check_range+0x293/0x2a0 mm/kasan/generic.c:189
 memcpy+0x44/0x70 mm/kasan/shadow.c:66
 ext4_insert_dentry+0x392/0x710 fs/ext4/namei.c:2117
 add_dirent_to_buf+0x3ac/0x780 fs/ext4/namei.c:2161
 make_indexed_dir+0xe9f/0x1500 fs/ext4/namei.c:2352
 ext4_add_entry+0xdcf/0x1280 fs/ext4/namei.c:2458
 ext4_mkdir+0x4d2/0xba0 fs/ext4/namei.c:3017
 vfs_mkdir+0x4cf/0x6c0 fs/namei.c:3790
 do_mkdirat+0x1a6/0x2c0 fs/namei.c:3812
 __do_sys_mkdirat fs/namei.c:3823 [inline]
 __se_sys_mkdirat fs/namei.c:3821 [inline]
 __x64_sys_mkdirat+0x7b/0x90 fs/namei.c:3821
 do_syscall_64+0x34/0x70
 entry_SYSCALL_64_after_hwframe+0x61/0xcb
RIP: 0033:0x7fedec13e819
Code: ff ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 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 a8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007fedea775038 EFLAGS: 00000246 ORIG_RAX: 0000000000000102
RAX: ffffffffffffffda RBX: 00007fedec2f6160 RCX: 00007fedec13e819
RDX: 0000000000000000 RSI: 00000000200005c0 RDI: ffffffffffffff9c
RBP: 00007fedec1b175e R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 0000000000000000 R14: 00007fedec2f6160 R15: 00007ffeafc2be78

The buggy address belongs to the page:
page:ffffea0004b2dd80 refcount:3 mapcount:0 mapping:ffff888109195c10 index:0x3f pfn:0x12cb76
aops:def_blk_aops ino:0
flags: 0x400000000000202a(referenced|dirty|active|private)
raw: 400000000000202a dead000000000100 dead000000000122 ffff888109195c10
raw: 000000000000003f ffff88812c278498 00000003ffffffff ffff88810fa78000
page dumped because: kasan: bad access detected
page->mem_cgroup:ffff88810fa78000
page_owner tracks the page as allocated
page last allocated via order 0, migratetype Movable, gfp_mask 0x108c48(GFP_NOFS|__GFP_NOFAIL|__GFP_HARDWALL|__GFP_MOVABLE), pid 587, ts 31742043051, free_ts 31505835695
 set_page_owner include/linux/page_owner.h:35 [inline]
 post_alloc_hook mm/page_alloc.c:2456 [inline]
 prep_new_page+0x166/0x180 mm/page_alloc.c:2462
 get_page_from_freelist+0x2d8c/0x2f30 mm/page_alloc.c:4254
 __alloc_pages_nodemask+0x435/0xaf0 mm/page_alloc.c:5348
 __alloc_pages include/linux/gfp.h:544 [inline]
 __alloc_pages_node include/linux/gfp.h:557 [inline]
 alloc_pages_node include/linux/gfp.h:571 [inline]
 alloc_pages include/linux/gfp.h:590 [inline]
 __page_cache_alloc include/linux/pagemap.h:290 [inline]
 pagecache_get_page+0x669/0x950 mm/filemap.c:1848
 find_or_create_page include/linux/pagemap.h:402 [inline]
 grow_dev_page fs/buffer.c:976 [inline]
 grow_buffers fs/buffer.c:1045 [inline]
 __getblk_slow fs/buffer.c:1072 [inline]
 __getblk_gfp+0x221/0x7e0 fs/buffer.c:1370
 sb_getblk include/linux/buffer_head.h:361 [inline]
 ext4_getblk+0x259/0x660 fs/ext4/inode.c:877
 ext4_bread+0x2f/0x1b0 fs/ext4/inode.c:922
 ext4_append+0x29a/0x4d0 fs/ext4/namei.c:83
 make_indexed_dir+0x505/0x1500 fs/ext4/namei.c:2278
 ext4_add_entry+0xdcf/0x1280 fs/ext4/namei.c:2458
 ext4_mkdir+0x4d2/0xba0 fs/ext4/namei.c:3017
 vfs_mkdir+0x4cf/0x6c0 fs/namei.c:3790
 do_mkdirat+0x1a6/0x2c0 fs/namei.c:3812
 __do_sys_mkdirat fs/namei.c:3823 [inline]
 __se_sys_mkdirat fs/namei.c:3821 [inline]
 __x64_sys_mkdirat+0x7b/0x90 fs/namei.c:3821
 do_syscall_64+0x34/0x70
 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_pcp_prepare mm/page_alloc.c:1421 [inline]
 free_unref_page_prepare+0x2ae/0x2d0 mm/page_alloc.c:3336
 free_unref_page_list+0x122/0xb20 mm/page_alloc.c:3443
 release_pages+0xea0/0xef0 mm/swap.c:1103
 __pagevec_release+0x84/0x100 mm/swap.c:1123
 pagevec_release include/linux/pagevec.h:88 [inline]
 shmem_undo_range+0x7d1/0x1a60 mm/shmem.c:965
 shmem_truncate_range mm/shmem.c:1069 [inline]
 shmem_evict_inode+0x215/0x9d0 mm/shmem.c:1169
 evict+0x526/0x9c0 fs/inode.c:612
 iput_final fs/inode.c:1732 [inline]
 iput+0x632/0x7e0 fs/inode.c:1758
 dentry_unlink_inode+0x2ea/0x3d0 fs/dcache.c:378
 __dentry_kill+0x447/0x650 fs/dcache.c:583
 dentry_kill+0xc0/0x2a0
 dput+0x40/0x80 fs/dcache.c:883
 __fput+0x52e/0x7b0 fs/file_table.c:294
 ____fput+0x15/0x20 fs/file_table.c:314
 task_work_run+0x129/0x190 kernel/task_work.c:189
 tracehook_notify_resume include/linux/tracehook.h:188 [inline]
 exit_to_user_mode_loop+0xbf/0xd0 kernel/entry/common.c:172

Memory state around the buggy address:
 ffff88812cb76f00: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
 ffff88812cb76f80: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
>ffff88812cb77000: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
                   ^
 ffff88812cb77080: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
 ffff88812cb77100: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
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