EXT4-fs warning (device loop1): dx_probe:966: inode #18: comm syz.1.49: Corrupt directory, running e2fsck is recommended
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BUG: KASAN: use-after-free in __ext4_check_dir_entry+0x6fd/0x880 fs/ext4/dir.c:85
Read of size 2 at addr ffff88805d967003 by task syz.1.49/5736

CPU: 0 UID: 0 PID: 5736 Comm: syz.1.49 Not tainted 6.12.0-rc1-syzkaller-00031-ge32cde8d2bd7 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 09/13/2024
Call Trace:
 <TASK>
 __dump_stack lib/dump_stack.c:94 [inline]
 dump_stack_lvl+0x241/0x360 lib/dump_stack.c:120
 print_address_description mm/kasan/report.c:377 [inline]
 print_report+0x169/0x550 mm/kasan/report.c:488
 kasan_report+0x143/0x180 mm/kasan/report.c:601
 __ext4_check_dir_entry+0x6fd/0x880 fs/ext4/dir.c:85
 ext4_readdir+0x1436/0x3a60 fs/ext4/dir.c:259
 iterate_dir+0x571/0x800 fs/readdir.c:108
 __do_sys_getdents64 fs/readdir.c:407 [inline]
 __se_sys_getdents64+0x1d3/0x4a0 fs/readdir.c:392
 do_syscall_x64 arch/x86/entry/common.c:52 [inline]
 do_syscall_64+0xf3/0x230 arch/x86/entry/common.c:83
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7fcaf517dff9
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:00007fcaf5fa1038 EFLAGS: 00000246 ORIG_RAX: 00000000000000d9
RAX: ffffffffffffffda RBX: 00007fcaf5335f80 RCX: 00007fcaf517dff9
RDX: 0000000000000010 RSI: 0000000000000000 RDI: 0000000000000009
RBP: 00007fcaf51f0296 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 0000000000000000 R14: 00007fcaf5335f80 R15: 00007ffd706849f8
 </TASK>

The buggy address belongs to the physical page:
page: refcount:0 mapcount:0 mapping:0000000000000000 index:0x3e pfn:0x5d967
flags: 0xfff00000000000(node=0|zone=1|lastcpupid=0x7ff)
raw: 00fff00000000000 ffffea0001765a08 ffff8880b8644af0 0000000000000000
raw: 000000000000003e 0000000000000000 00000000ffffffff 0000000000000000
page dumped because: kasan: bad access detected
page_owner tracks the page as freed
page last allocated via order 0, migratetype Movable, gfp_mask 0x140cca(GFP_HIGHUSER_MOVABLE|__GFP_COMP), pid 5736, tgid 5735 (syz.1.49), ts 100015346117, free_ts 100017599160
 set_page_owner include/linux/page_owner.h:32 [inline]
 post_alloc_hook+0x1f3/0x230 mm/page_alloc.c:1537
 prep_new_page mm/page_alloc.c:1545 [inline]
 get_page_from_freelist+0x3039/0x3180 mm/page_alloc.c:3457
 __alloc_pages_noprof+0x256/0x6c0 mm/page_alloc.c:4733
 alloc_pages_mpol_noprof+0x3e8/0x680 mm/mempolicy.c:2265
 folio_alloc_mpol_noprof+0x36/0x50 mm/mempolicy.c:2283
 shmem_alloc_folio mm/shmem.c:1774 [inline]
 shmem_alloc_and_add_folio+0x49b/0x13d0 mm/shmem.c:1813
 shmem_get_folio_gfp+0x5a9/0x20a0 mm/shmem.c:2335
 shmem_get_folio mm/shmem.c:2441 [inline]
 shmem_write_begin+0x17e/0x460 mm/shmem.c:3046
 generic_perform_write+0x344/0x6d0 mm/filemap.c:4054
 shmem_file_write_iter+0xf9/0x120 mm/shmem.c:3221
 new_sync_write fs/read_write.c:590 [inline]
 vfs_write+0xa6d/0xc90 fs/read_write.c:683
 ksys_write+0x183/0x2b0 fs/read_write.c:736
 do_syscall_x64 arch/x86/entry/common.c:52 [inline]
 do_syscall_64+0xf3/0x230 arch/x86/entry/common.c:83
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
page last free pid 5736 tgid 5735 stack trace:
 reset_page_owner include/linux/page_owner.h:25 [inline]
 free_pages_prepare mm/page_alloc.c:1108 [inline]
 free_unref_folios+0xee2/0x18a0 mm/page_alloc.c:2686
 folios_put_refs+0x76c/0x860 mm/swap.c:1007
 folio_batch_release include/linux/pagevec.h:101 [inline]
 shmem_undo_range+0x64c/0x1cf0 mm/shmem.c:1032
 shmem_truncate_range mm/shmem.c:1144 [inline]
 shmem_evict_inode+0x29b/0xa80 mm/shmem.c:1272
 evict+0x4e8/0x9b0 fs/inode.c:723
 __dentry_kill+0x20d/0x630 fs/dcache.c:615
 dput+0x19f/0x2b0 fs/dcache.c:857
 __fput+0x5d2/0x880 fs/file_table.c:439
 __do_sys_close fs/open.c:1565 [inline]
 __se_sys_close fs/open.c:1550 [inline]
 __x64_sys_close+0x7f/0x110 fs/open.c:1550
 do_syscall_x64 arch/x86/entry/common.c:52 [inline]
 do_syscall_64+0xf3/0x230 arch/x86/entry/common.c:83
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

Memory state around the buggy address:
 ffff88805d966f00: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
 ffff88805d966f80: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
>ffff88805d967000: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
                   ^
 ffff88805d967080: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
 ffff88805d967100: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
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