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BUG: KASAN: use-after-free in ext4_search_dir+0x1b7/0x1d0 fs/ext4/namei.c:1539
Read of size 1 at addr ffff88809b3491ec by task syz-executor.2/11729

CPU: 0 PID: 11729 Comm: syz-executor.2 Not tainted 6.6.0-rc1-next-20230915-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 08/04/2023
Call Trace:
 <TASK>
 __dump_stack lib/dump_stack.c:88 [inline]
 dump_stack_lvl+0xd9/0x1b0 lib/dump_stack.c:106
 print_address_description mm/kasan/report.c:364 [inline]
 print_report+0xc4/0x620 mm/kasan/report.c:475
 kasan_report+0xda/0x110 mm/kasan/report.c:588
 ext4_search_dir+0x1b7/0x1d0 fs/ext4/namei.c:1539
 ext4_find_inline_entry+0x432/0x4f0 fs/ext4/inline.c:1694
 __ext4_find_entry+0x85e/0x1050 fs/ext4/namei.c:1612
 ext4_lookup_entry fs/ext4/namei.c:1767 [inline]
 ext4_lookup+0x543/0x740 fs/ext4/namei.c:1835
 lookup_open.isra.0+0x926/0x13b0 fs/namei.c:3454
 open_last_lookups fs/namei.c:3544 [inline]
 path_openat+0x931/0x29c0 fs/namei.c:3774
 do_filp_open+0x1de/0x430 fs/namei.c:3804
 do_sys_openat2+0x176/0x1e0 fs/open.c:1422
 do_sys_open fs/open.c:1437 [inline]
 __do_sys_creat fs/open.c:1513 [inline]
 __se_sys_creat fs/open.c:1507 [inline]
 __x64_sys_creat+0xcd/0x120 fs/open.c:1507
 do_syscall_x64 arch/x86/entry/common.c:51 [inline]
 do_syscall_64+0x38/0xb0 arch/x86/entry/common.c:81
 entry_SYSCALL_64_after_hwframe+0x63/0xcd
RIP: 0033:0x7fb3f6e7cae9
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:00007fb3f7b0b0c8 EFLAGS: 00000246 ORIG_RAX: 0000000000000055
RAX: ffffffffffffffda RBX: 00007fb3f6f9bf80 RCX: 00007fb3f6e7cae9
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000020000940
RBP: 00007fb3f6ec847a R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 000000000000000b R14: 00007fb3f6f9bf80 R15: 00007ffd0441cdd8
 </TASK>

The buggy address belongs to the physical page:
page:ffffea00026cd240 refcount:0 mapcount:0 mapping:0000000000000000 index:0xb36 pfn:0x9b349
flags: 0xfff00000000000(node=0|zone=1|lastcpupid=0x7ff)
page_type: 0xffffffff()
raw: 00fff00000000000 dead000000000100 dead000000000122 0000000000000000
raw: 0000000000000b36 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 10721, tgid 10720 (syz-executor.0), ts 1032652847004, free_ts 1033458295051
 set_page_owner include/linux/page_owner.h:31 [inline]
 post_alloc_hook+0x2cf/0x340 mm/page_alloc.c:1535
 prep_new_page mm/page_alloc.c:1542 [inline]
 get_page_from_freelist+0xdcd/0x2d10 mm/page_alloc.c:3224
 __alloc_pages+0x1d0/0x4a0 mm/page_alloc.c:4480
 __folio_alloc+0x16/0x40 mm/page_alloc.c:4512
 vma_alloc_folio+0x156/0x890 mm/mempolicy.c:2259
 shmem_alloc_folio+0xb5/0x170 mm/shmem.c:1675
 shmem_alloc_and_acct_folio+0xcb/0x140 mm/shmem.c:1700
 shmem_get_folio_gfp+0xbd9/0x1870 mm/shmem.c:2037
 shmem_get_folio mm/shmem.c:2160 [inline]
 shmem_write_begin+0x15c/0x370 mm/shmem.c:2705
 generic_perform_write+0x278/0x600 mm/filemap.c:3955
 shmem_file_write_iter+0x110/0x140 mm/shmem.c:2882
 call_write_iter include/linux/fs.h:1986 [inline]
 new_sync_write fs/read_write.c:491 [inline]
 vfs_write+0x650/0xe40 fs/read_write.c:584
 ksys_write+0x12f/0x250 fs/read_write.c:637
 do_syscall_x64 arch/x86/entry/common.c:51 [inline]
 do_syscall_64+0x38/0xb0 arch/x86/entry/common.c:81
 entry_SYSCALL_64_after_hwframe+0x63/0xcd
page last free stack trace:
 reset_page_owner include/linux/page_owner.h:24 [inline]
 free_pages_prepare mm/page_alloc.c:1138 [inline]
 free_unref_page_list+0x4eb/0x1050 mm/page_alloc.c:2507
 release_pages+0x32a/0x14e0 mm/swap.c:1042
 __folio_batch_release+0x77/0xe0 mm/swap.c:1062
 folio_batch_release include/linux/pagevec.h:83 [inline]
 shmem_undo_range+0x580/0x1140 mm/shmem.c:1022
 shmem_truncate_range mm/shmem.c:1131 [inline]
 shmem_evict_inode+0x392/0xb50 mm/shmem.c:1260
 evict+0x2ed/0x6b0 fs/inode.c:666
 iput_final fs/inode.c:1777 [inline]
 iput.part.0+0x55e/0x7a0 fs/inode.c:1803
 iput+0x5c/0x80 fs/inode.c:1793
 dentry_unlink_inode+0x292/0x430 fs/dcache.c:401
 __dentry_kill+0x3b8/0x640 fs/dcache.c:607
 dentry_kill fs/dcache.c:733 [inline]
 dput+0x8b7/0xf80 fs/dcache.c:913
 __fput+0x536/0xa70 fs/file_table.c:392
 __fput_sync+0x47/0x50 fs/file_table.c:465
 __do_sys_close fs/open.c:1572 [inline]
 __se_sys_close fs/open.c:1557 [inline]
 __x64_sys_close+0x87/0xf0 fs/open.c:1557
 do_syscall_x64 arch/x86/entry/common.c:51 [inline]
 do_syscall_64+0x38/0xb0 arch/x86/entry/common.c:81
 entry_SYSCALL_64_after_hwframe+0x63/0xcd

Memory state around the buggy address:
 ffff88809b349080: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
 ffff88809b349100: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
>ffff88809b349180: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
                                                          ^
 ffff88809b349200: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
 ffff88809b349280: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
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