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BUG: KASAN: use-after-free in ext4_insert_dentry+0x389/0x720 fs/ext4/namei.c:2155
Write of size 250 at addr ffff888125f7af18 by task syz.2.15/561

CPU: 1 PID: 561 Comm: syz.2.15 Not tainted 6.1.115-syzkaller-00090-g0d968ced7330 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 09/13/2024
Call Trace:
 <TASK>
 __dump_stack lib/dump_stack.c:88 [inline]
 dump_stack_lvl+0x151/0x1b7 lib/dump_stack.c:106
 print_address_description mm/kasan/report.c:284 [inline]
 print_report+0x158/0x4e0 mm/kasan/report.c:395
 kasan_report+0x13c/0x170 mm/kasan/report.c:495
 kasan_check_range+0x294/0x2a0 mm/kasan/generic.c:189
 memcpy+0x44/0x70 mm/kasan/shadow.c:66
 ext4_insert_dentry+0x389/0x720 fs/ext4/namei.c:2155
 add_dirent_to_buf+0x38c/0x780 fs/ext4/namei.c:2200
 make_indexed_dir+0xf29/0x1590 fs/ext4/namei.c:2398
 ext4_add_entry+0xbbf/0xed0 fs/ext4/namei.c:2504
 ext4_mkdir+0x54f/0xce0 fs/ext4/namei.c:3081
 vfs_mkdir+0x398/0x570 fs/namei.c:4106
 do_mkdirat+0x1dc/0x2c0 fs/namei.c:4131
 __do_sys_mkdirat fs/namei.c:4146 [inline]
 __se_sys_mkdirat fs/namei.c:4144 [inline]
 __x64_sys_mkdirat+0x89/0xa0 fs/namei.c:4144
 x64_sys_call+0x6c6/0x9a0 arch/x86/include/generated/asm/syscalls_64.h:259
 do_syscall_x64 arch/x86/entry/common.c:51 [inline]
 do_syscall_64+0x3b/0xb0 arch/x86/entry/common.c:81
 entry_SYSCALL_64_after_hwframe+0x68/0xd2
RIP: 0033:0x7f6b09180849
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:00007f6b09ec4058 EFLAGS: 00000246 ORIG_RAX: 0000000000000102
RAX: ffffffffffffffda RBX: 00007f6b09345fa0 RCX: 00007f6b09180849
RDX: 0000000000000000 RSI: 00000000200005c0 RDI: ffffffffffffff9c
RBP: 00007f6b091f3986 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 0000000000000000 R14: 00007f6b09345fa0 R15: 00007fffb9d11478
 </TASK>

The buggy address belongs to the physical page:
page:ffffea000497de80 refcount:3 mapcount:0 mapping:ffff88810b19ea50 index:0x3f pfn:0x125f7a
memcg:ffff888114774000
aops:def_blk_aops ino:700002
flags: 0x420000000000204a(referenced|dirty|workingset|private|zone=1)
raw: 420000000000204a 0000000000000000 dead000000000122 ffff88810b19ea50
raw: 000000000000003f ffff888112db82a0 00000003ffffffff ffff888114774000
page dumped because: kasan: bad access detected
page_owner tracks the page as allocated
page last allocated via order 0, migratetype Movable, gfp_mask 0x148c48(GFP_NOFS|__GFP_NOFAIL|__GFP_COMP|__GFP_HARDWALL|__GFP_MOVABLE), pid 561, tgid 560 (syz.2.15), ts 54277141189, free_ts 53799551441
 set_page_owner include/linux/page_owner.h:31 [inline]
 post_alloc_hook+0x1e2/0x1f0 mm/page_alloc.c:2517
 prep_new_page mm/page_alloc.c:2524 [inline]
 get_page_from_freelist+0x2e1c/0x2ef0 mm/page_alloc.c:4290
 __alloc_pages+0x3c2/0x7d0 mm/page_alloc.c:5558
 __folio_alloc+0x15/0x40 mm/page_alloc.c:5590
 __folio_alloc_node include/linux/gfp.h:246 [inline]
 folio_alloc include/linux/gfp.h:275 [inline]
 filemap_alloc_folio include/linux/pagemap.h:507 [inline]
 __filemap_get_folio+0x6c0/0x970 mm/filemap.c:1993
 pagecache_get_page+0x2f/0x110 mm/folio-compat.c:110
 find_or_create_page include/linux/pagemap.h:646 [inline]
 grow_dev_page fs/buffer.c:946 [inline]
 grow_buffers fs/buffer.c:1011 [inline]
 __getblk_slow fs/buffer.c:1038 [inline]
 __getblk_gfp+0x205/0x7d0 fs/buffer.c:1333
 sb_getblk include/linux/buffer_head.h:356 [inline]
 ext4_getblk+0x2a7/0x7b0 fs/ext4/inode.c:899
 ext4_bread+0x2f/0x180 fs/ext4/inode.c:945
 ext4_append+0x31f/0x5b0 fs/ext4/namei.c:83
 make_indexed_dir+0x518/0x1590 fs/ext4/namei.c:2318
 ext4_add_entry+0xbbf/0xed0 fs/ext4/namei.c:2504
 ext4_mkdir+0x54f/0xce0 fs/ext4/namei.c:3081
 vfs_mkdir+0x398/0x570 fs/namei.c:4106
 do_mkdirat+0x1dc/0x2c0 fs/namei.c:4131
 __do_sys_mkdirat fs/namei.c:4146 [inline]
 __se_sys_mkdirat fs/namei.c:4144 [inline]
 __x64_sys_mkdirat+0x89/0xa0 fs/namei.c:4144
page last free stack trace:
 reset_page_owner include/linux/page_owner.h:24 [inline]
 free_pages_prepare mm/page_alloc.c:1444 [inline]
 free_pcp_prepare mm/page_alloc.c:1517 [inline]
 free_unref_page_prepare+0x83d/0x850 mm/page_alloc.c:3369
 free_unref_page_list+0xf1/0x7b0 mm/page_alloc.c:3510
 release_pages+0xf7f/0xfe0 mm/swap.c:1055
 free_pages_and_swap_cache+0x8a/0xa0 mm/swap_state.c:314
 tlb_batch_pages_flush mm/mmu_gather.c:59 [inline]
 tlb_flush_mmu_free mm/mmu_gather.c:254 [inline]
 tlb_flush_mmu mm/mmu_gather.c:261 [inline]
 tlb_finish_mmu+0x1e0/0x3f0 mm/mmu_gather.c:361
 exit_mmap+0x38a/0x800 mm/mmap.c:3239
 __mmput+0x95/0x310 kernel/fork.c:1199
 mmput+0x54/0x70 kernel/fork.c:1221
 exit_mm kernel/exit.c:565 [inline]
 do_exit+0xaf9/0x2910 kernel/exit.c:858
 do_group_exit+0x21a/0x2d0 kernel/exit.c:1021
 get_signal+0x169d/0x1820 kernel/signal.c:2870
 arch_do_signal_or_restart+0xb0/0x16f0 arch/x86/kernel/signal.c:871
 exit_to_user_mode_loop+0x74/0xa0 kernel/entry/common.c:174
 exit_to_user_mode_prepare+0x5a/0xa0 kernel/entry/common.c:210
 __syscall_exit_to_user_mode_work kernel/entry/common.c:292 [inline]
 syscall_exit_to_user_mode+0x26/0x130 kernel/entry/common.c:303
 do_syscall_64+0x47/0xb0 arch/x86/entry/common.c:87

Memory state around the buggy address:
 ffff888125f7af00: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
 ffff888125f7af80: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
>ffff888125f7b000: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
                   ^
 ffff888125f7b080: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
 ffff888125f7b100: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
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