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BUG: KASAN: use-after-free in ext4_search_dir+0xf2/0x1b0 fs/ext4/namei.c:1543
Read of size 1 at addr ffff888035c401ec by task syz-executor.1/12976

CPU: 1 PID: 12976 Comm: syz-executor.1 Not tainted 6.7.0-rc6-syzkaller-00168-g9a6b294ab496 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 11/17/2023
Call Trace:
 <TASK>
 __dump_stack lib/dump_stack.c:88 [inline]
 dump_stack_lvl+0x1e7/0x2d0 lib/dump_stack.c:106
 print_address_description mm/kasan/report.c:364 [inline]
 print_report+0x163/0x540 mm/kasan/report.c:475
 kasan_report+0x142/0x170 mm/kasan/report.c:588
 ext4_search_dir+0xf2/0x1b0 fs/ext4/namei.c:1543
 ext4_find_inline_entry+0x4ba/0x5e0 fs/ext4/inline.c:1694
 __ext4_find_entry+0x2b4/0x1b30 fs/ext4/namei.c:1616
 ext4_lookup_entry fs/ext4/namei.c:1771 [inline]
 ext4_lookup+0x17a/0x750 fs/ext4/namei.c:1839
 __lookup_slow+0x282/0x3e0 fs/namei.c:1694
 lookup_slow+0x53/0x70 fs/namei.c:1711
 walk_component+0x2d0/0x400 fs/namei.c:2002
 lookup_last fs/namei.c:2459 [inline]
 path_lookupat+0x16f/0x450 fs/namei.c:2483
 do_o_path+0x95/0x230 fs/namei.c:3750
 path_openat+0x2a84/0x3290 fs/namei.c:3772
 do_filp_open+0x234/0x490 fs/namei.c:3809
 do_sys_openat2+0x13e/0x1d0 fs/open.c:1437
 do_sys_open fs/open.c:1452 [inline]
 __do_sys_open fs/open.c:1460 [inline]
 __se_sys_open fs/open.c:1456 [inline]
 __x64_sys_open+0x225/0x270 fs/open.c:1456
 do_syscall_x64 arch/x86/entry/common.c:52 [inline]
 do_syscall_64+0x45/0x110 arch/x86/entry/common.c:83
 entry_SYSCALL_64_after_hwframe+0x63/0x6b
RIP: 0033:0x7f62bc27cce9
Code: 28 00 00 00 75 05 48 83 c4 28 c3 e8 e1 20 00 00 90 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 b0 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007f62bcf6a0c8 EFLAGS: 00000246 ORIG_RAX: 0000000000000002
RAX: ffffffffffffffda RBX: 00007f62bc39bf80 RCX: 00007f62bc27cce9
RDX: 0000000000000000 RSI: 0000000000248242 RDI: 00000000200000c0
RBP: 00007f62bc2c947a R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 000000000000000b R14: 00007f62bc39bf80 R15: 00007ffcb2fa0de8
 </TASK>

The buggy address belongs to the physical page:
page:ffffea0000d71000 refcount:0 mapcount:-128 mapping:0000000000000000 index:0x1 pfn:0x35c40
flags: 0xfff00000000000(node=0|zone=1|lastcpupid=0x7ff)
page_type: 0xffffff7f(buddy)
raw: 00fff00000000000 ffffea00012c7008 ffffea0000f05008 0000000000000000
raw: 0000000000000001 0000000000000006 00000000ffffff7f 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 0x100cca(GFP_HIGHUSER_MOVABLE), pid 12434, tgid 12432 (syz-executor.5), ts 423704918662, free_ts 423961517521
 set_page_owner include/linux/page_owner.h:31 [inline]
 post_alloc_hook+0x1e6/0x210 mm/page_alloc.c:1537
 prep_new_page mm/page_alloc.c:1544 [inline]
 get_page_from_freelist+0x33ea/0x3570 mm/page_alloc.c:3312
 __alloc_pages+0x255/0x680 mm/page_alloc.c:4568
 alloc_pages_mpol+0x3de/0x640 mm/mempolicy.c:2133
 shmem_alloc_folio mm/shmem.c:1630 [inline]
 shmem_alloc_and_add_folio+0x24f/0xde0 mm/shmem.c:1670
 shmem_get_folio_gfp+0x7c3/0x1ee0 mm/shmem.c:2054
 shmem_get_folio mm/shmem.c:2136 [inline]
 shmem_write_begin+0x170/0x4c0 mm/shmem.c:2719
 generic_perform_write+0x31b/0x630 mm/filemap.c:3918
 shmem_file_write_iter+0xfc/0x120 mm/shmem.c:2895
 call_write_iter include/linux/fs.h:2020 [inline]
 new_sync_write fs/read_write.c:491 [inline]
 vfs_write+0x792/0xb20 fs/read_write.c:584
 ksys_write+0x1a0/0x2c0 fs/read_write.c:637
 do_syscall_x64 arch/x86/entry/common.c:52 [inline]
 do_syscall_64+0x45/0x110 arch/x86/entry/common.c:83
 entry_SYSCALL_64_after_hwframe+0x63/0x6b
page last free stack trace:
 reset_page_owner include/linux/page_owner.h:24 [inline]
 free_pages_prepare mm/page_alloc.c:1137 [inline]
 free_unref_page_prepare+0x931/0xa60 mm/page_alloc.c:2347
 free_unref_page_list+0x5a0/0x840 mm/page_alloc.c:2533
 release_pages+0x2117/0x2400 mm/swap.c:1042
 __folio_batch_release+0x84/0x100 mm/swap.c:1062
 folio_batch_release include/linux/pagevec.h:83 [inline]
 shmem_undo_range+0x6b5/0x1da0 mm/shmem.c:1004
 shmem_truncate_range mm/shmem.c:1113 [inline]
 shmem_evict_inode+0x29b/0xa60 mm/shmem.c:1241
 evict+0x2a4/0x630 fs/inode.c:666
 __dentry_kill+0x436/0x660 fs/dcache.c:607
 dentry_kill+0xbb/0x290
 dput+0x21e/0x470 fs/dcache.c:913
 __fput+0x60b/0x9e0 fs/file_table.c:402
 __do_sys_close fs/open.c:1587 [inline]
 __se_sys_close fs/open.c:1572 [inline]
 __x64_sys_close+0x7e/0x100 fs/open.c:1572
 do_syscall_x64 arch/x86/entry/common.c:52 [inline]
 do_syscall_64+0x45/0x110 arch/x86/entry/common.c:83
 entry_SYSCALL_64_after_hwframe+0x63/0x6b

Memory state around the buggy address:
 ffff888035c40080: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
 ffff888035c40100: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
>ffff888035c40180: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
                                                          ^
 ffff888035c40200: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
 ffff888035c40280: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
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