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BUG: KASAN: use-after-free in ext4_search_dir+0xf2/0x1b0 fs/ext4/namei.c:1539
Read of size 1 at addr ffff888033a63a55 by task syz-executor.0/13410

CPU: 0 PID: 13410 Comm: syz-executor.0 Not tainted 6.5.0-syzkaller-00453-g727dbda16b83 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/26/2023
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+0x175/0x1b0 mm/kasan/report.c:588
 ext4_search_dir+0xf2/0x1b0 fs/ext4/namei.c:1539
 ext4_find_inline_entry+0x4ba/0x5e0 fs/ext4/inline.c:1694
 __ext4_find_entry+0x2b4/0x1b30 fs/ext4/namei.c:1612
 ext4_lookup_entry fs/ext4/namei.c:1767 [inline]
 ext4_lookup+0x17a/0x750 fs/ext4/namei.c:1835
 __lookup_slow+0x282/0x3e0 fs/namei.c:1693
 lookup_slow+0x53/0x70 fs/namei.c:1710
 walk_component fs/namei.c:2001 [inline]
 link_path_walk+0x9c8/0xe70 fs/namei.c:2328
 path_openat+0x249/0x3180 fs/namei.c:3792
 do_filp_open+0x234/0x490 fs/namei.c:3823
 do_sys_openat2+0x13e/0x1d0 fs/open.c:1422
 do_sys_open fs/open.c:1437 [inline]
 __do_sys_open fs/open.c:1445 [inline]
 __se_sys_open fs/open.c:1441 [inline]
 __x64_sys_open+0x225/0x270 fs/open.c:1441
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x41/0xc0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x63/0xcd
RIP: 0033:0x7fcdad87cae9
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:00007fcdae51d0c8 EFLAGS: 00000246 ORIG_RAX: 0000000000000002
RAX: ffffffffffffffda RBX: 00007fcdad99c050 RCX: 00007fcdad87cae9
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000020000000
RBP: 00007fcdad8c847a R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 000000000000006e R14: 00007fcdad99c050 R15: 00007ffedeb60a98
 </TASK>

The buggy address belongs to the physical page:
page:ffffea0000ce98c0 refcount:0 mapcount:0 mapping:0000000000000000 index:0x1 pfn:0x33a63
flags: 0xfff00000000000(node=0|zone=1|lastcpupid=0x7ff)
page_type: 0xffffffff()
raw: 00fff00000000000 dead000000000100 dead000000000122 0000000000000000
raw: 0000000000000001 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 8049, tgid 8047 (syz-executor.0), ts 238516109482, free_ts 241152714272
 set_page_owner include/linux/page_owner.h:31 [inline]
 post_alloc_hook+0x1e6/0x210 mm/page_alloc.c:1570
 prep_new_page mm/page_alloc.c:1577 [inline]
 get_page_from_freelist+0x31e8/0x3370 mm/page_alloc.c:3221
 __alloc_pages+0x255/0x670 mm/page_alloc.c:4477
 __folio_alloc+0x13/0x30 mm/page_alloc.c:4509
 vma_alloc_folio+0x48a/0x9a0 mm/mempolicy.c:2259
 shmem_alloc_folio mm/shmem.c:1658 [inline]
 shmem_alloc_and_acct_folio+0x438/0x9b0 mm/shmem.c:1683
 shmem_get_folio_gfp+0xca9/0x2bd0 mm/shmem.c:2020
 shmem_get_folio mm/shmem.c:2143 [inline]
 shmem_write_begin+0x172/0x4e0 mm/shmem.c:2688
 generic_perform_write+0x31b/0x630 mm/filemap.c:3928
 shmem_file_write_iter+0xfc/0x120 mm/shmem.c:2865
 call_write_iter include/linux/fs.h:1985 [inline]
 new_sync_write fs/read_write.c:491 [inline]
 vfs_write+0x782/0xaf0 fs/read_write.c:584
 ksys_write+0x1a0/0x2c0 fs/read_write.c:637
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x41/0xc0 arch/x86/entry/common.c:80
 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:1161 [inline]
 free_unref_page_prepare+0x903/0xa30 mm/page_alloc.c:2348
 free_unref_page_list+0x596/0x830 mm/page_alloc.c:2489
 release_pages+0x2193/0x2470 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+0x6b2/0x1a10 mm/shmem.c:1022
 shmem_truncate_range mm/shmem.c:1114 [inline]
 shmem_evict_inode+0x29e/0xa80 mm/shmem.c:1243
 evict+0x2a4/0x620 fs/inode.c:664
 __dentry_kill+0x436/0x650 fs/dcache.c:607
 dentry_kill+0xbb/0x290
 dput+0x1f3/0x420 fs/dcache.c:913
 __fput+0x60d/0x910 fs/file_table.c:392
 task_work_run+0x24a/0x300 kernel/task_work.c:179
 resume_user_mode_work include/linux/resume_user_mode.h:49 [inline]
 exit_to_user_mode_loop+0xd9/0x100 kernel/entry/common.c:171
 exit_to_user_mode_prepare+0xb1/0x140 kernel/entry/common.c:204
 __syscall_exit_to_user_mode_work kernel/entry/common.c:286 [inline]
 syscall_exit_to_user_mode+0x64/0x280 kernel/entry/common.c:297
 do_syscall_64+0x4d/0xc0 arch/x86/entry/common.c:86

Memory state around the buggy address:
 ffff888033a63900: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
 ffff888033a63980: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
>ffff888033a63a00: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
                                                 ^
 ffff888033a63a80: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
 ffff888033a63b00: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
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