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BUG: KASAN: use-after-free in ext4_search_dir+0xf2/0x1c0 fs/ext4/namei.c:1500
Read of size 1 at addr ffff888058f2eb1a by task syz.4.565/10905

CPU: 0 UID: 0 PID: 10905 Comm: syz.4.565 Not tainted 6.11.0-rc7-syzkaller-00021-g7c6a3a65ace7 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 08/06/2024
Call Trace:
 <TASK>
 __dump_stack lib/dump_stack.c:93 [inline]
 dump_stack_lvl+0x241/0x360 lib/dump_stack.c:119
 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_search_dir+0xf2/0x1c0 fs/ext4/namei.c:1500
 ext4_find_inline_entry+0x4be/0x5e0 fs/ext4/inline.c:1697
 __ext4_find_entry+0x2b4/0x1b30 fs/ext4/namei.c:1573
 ext4_lookup_entry fs/ext4/namei.c:1727 [inline]
 ext4_lookup+0x15f/0x750 fs/ext4/namei.c:1795
 __lookup_slow+0x28c/0x3f0 fs/namei.c:1718
 lookup_slow+0x53/0x70 fs/namei.c:1735
 walk_component+0x2e1/0x410 fs/namei.c:2039
 lookup_last fs/namei.c:2542 [inline]
 path_lookupat+0x16f/0x450 fs/namei.c:2566
 filename_lookup+0x256/0x610 fs/namei.c:2595
 do_linkat+0x13f/0x6f0 fs/namei.c:4742
 __do_sys_link fs/namei.c:4796 [inline]
 __se_sys_link fs/namei.c:4794 [inline]
 __x64_sys_link+0x82/0x90 fs/namei.c:4794
 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: 0033:0x7f28ac97def9
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:00007f28ad785038 EFLAGS: 00000246 ORIG_RAX: 0000000000000056
RAX: ffffffffffffffda RBX: 00007f28acb36058 RCX: 00007f28ac97def9
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000020002140
RBP: 00007f28ac9f0b76 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 0000000000000000 R14: 00007f28acb36058 R15: 00007ffeec5c40c8
 </TASK>

The buggy address belongs to the physical page:
page: refcount:0 mapcount:0 mapping:0000000000000000 index:0x5567db796 pfn:0x58f2e
flags: 0xfff00000000000(node=0|zone=1|lastcpupid=0x7ff)
raw: 00fff00000000000 ffffea000163cd48 ffffea000163cd88 0000000000000000
raw: 00000005567db796 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 10959, tgid 10959 (dhcpcd-run-hook), ts 479151428847, free_ts 479155905288
 set_page_owner include/linux/page_owner.h:32 [inline]
 post_alloc_hook+0x1f3/0x230 mm/page_alloc.c:1500
 prep_new_page mm/page_alloc.c:1508 [inline]
 get_page_from_freelist+0x2e4c/0x2f10 mm/page_alloc.c:3446
 __alloc_pages_noprof+0x256/0x6c0 mm/page_alloc.c:4702
 alloc_pages_mpol_noprof+0x3e8/0x680 mm/mempolicy.c:2263
 folio_alloc_mpol_noprof mm/mempolicy.c:2281 [inline]
 vma_alloc_folio_noprof+0x12e/0x230 mm/mempolicy.c:2312
 folio_prealloc+0x31/0x170
 wp_page_copy mm/memory.c:3335 [inline]
 do_wp_page+0x11cc/0x52f0 mm/memory.c:3727
 handle_pte_fault+0x115a/0x6fc0 mm/memory.c:5537
 __handle_mm_fault mm/memory.c:5664 [inline]
 handle_mm_fault+0x1056/0x1ad0 mm/memory.c:5832
 do_user_addr_fault arch/x86/mm/fault.c:1338 [inline]
 handle_page_fault arch/x86/mm/fault.c:1481 [inline]
 exc_page_fault+0x459/0x8c0 arch/x86/mm/fault.c:1539
 asm_exc_page_fault+0x26/0x30 arch/x86/include/asm/idtentry.h:623
page last free pid 10959 tgid 10959 stack trace:
 reset_page_owner include/linux/page_owner.h:25 [inline]
 free_pages_prepare mm/page_alloc.c:1101 [inline]
 free_unref_folios+0x100f/0x1ac0 mm/page_alloc.c:2667
 folios_put_refs+0x76e/0x860 mm/swap.c:1039
 free_pages_and_swap_cache+0x2ea/0x690 mm/swap_state.c:332
 __tlb_batch_free_encoded_pages mm/mmu_gather.c:136 [inline]
 tlb_batch_pages_flush mm/mmu_gather.c:149 [inline]
 tlb_flush_mmu_free mm/mmu_gather.c:366 [inline]
 tlb_flush_mmu+0x3a3/0x680 mm/mmu_gather.c:373
 tlb_finish_mmu+0xd4/0x200 mm/mmu_gather.c:465
 exit_mmap+0x44f/0xc80 mm/mmap.c:3425
 __mmput+0x115/0x380 kernel/fork.c:1345
 exit_mm+0x220/0x310 kernel/exit.c:571
 do_exit+0x9b2/0x27f0 kernel/exit.c:869
 do_group_exit+0x207/0x2c0 kernel/exit.c:1031
 __do_sys_exit_group kernel/exit.c:1042 [inline]
 __se_sys_exit_group kernel/exit.c:1040 [inline]
 __x64_sys_exit_group+0x3f/0x40 kernel/exit.c:1040
 x64_sys_call+0x2634/0x2640 arch/x86/include/generated/asm/syscalls_64.h:232
 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:
 ffff888058f2ea00: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
 ffff888058f2ea80: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
>ffff888058f2eb00: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
                            ^
 ffff888058f2eb80: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
 ffff888058f2ec00: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
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