[syzbot] [nilfs?] KASAN: use-after-free Read in nilfs_find_entry

[syzbot <syzbot+96d5d14c47d97015c624@syzkaller.appspotmail.com>]

Hello,

syzbot found the following issue on:

HEAD commit:    906bd684e4b1 Merge tag 'spi-fix-v6.12-rc6' of git://git.ke..
git tree:       upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=1418ee30580000
kernel config:  https://syzkaller.appspot.com/x/.config?x=64aa0d9945bd5c1
dashboard link: https://syzkaller.appspot.com/bug?extid=96d5d14c47d97015c624
compiler:       Debian clang version 15.0.6, GNU ld (GNU Binutils for Debian) 2.40
syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=1218ee30580000
C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=13647f40580000

Downloadable assets:
disk image (non-bootable): https://storage.googleapis.com/syzbot-assets/7feb34a89c2a/non_bootable_disk-906bd684.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/88c5c4ba7e33/vmlinux-906bd684.xz
kernel image: https://storage.googleapis.com/syzbot-assets/07094e69f47b/bzImage-906bd684.xz
mounted in repro: https://storage.googleapis.com/syzbot-assets/b427c083d0d8/mount_0.gz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+96d5d14c47d97015c624@syzkaller.appspotmail.com

=======================================================
==================================================================
BUG: KASAN: use-after-free in nilfs_find_entry+0x29c/0x660 fs/nilfs2/dir.c:321
Read of size 2 at addr ffff888048f39008 by task syz-executor334/5310

CPU: 0 UID: 0 PID: 5310 Comm: syz-executor334 Not tainted 6.12.0-rc6-syzkaller-00169-g906bd684e4b1 #0
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.3-debian-1.16.3-2~bpo12+1 04/01/2014
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
 nilfs_find_entry+0x29c/0x660 fs/nilfs2/dir.c:321
 nilfs_inode_by_name+0xad/0x240 fs/nilfs2/dir.c:394
 nilfs_lookup+0xed/0x210 fs/nilfs2/namei.c:63
 lookup_open fs/namei.c:3573 [inline]
 open_last_lookups fs/namei.c:3694 [inline]
 path_openat+0x11a7/0x3590 fs/namei.c:3930
 do_filp_open+0x235/0x490 fs/namei.c:3960
 do_sys_openat2+0x13e/0x1d0 fs/open.c:1415
 do_sys_open fs/open.c:1430 [inline]
 __do_sys_openat fs/open.c:1446 [inline]
 __se_sys_openat fs/open.c:1441 [inline]
 __x64_sys_openat+0x247/0x2a0 fs/open.c:1441
 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: 0033:0x7fd472823b99
Code: 28 00 00 00 75 05 48 83 c4 28 c3 e8 f1 17 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 b8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007fff91507d48 EFLAGS: 00000246 ORIG_RAX: 0000000000000101
RAX: ffffffffffffffda RBX: 6569727261626f6e RCX: 00007fd472823b99
RDX: 000000000000275a RSI: 0000000020000080 RDI: 00000000ffffff9c
RBP: 00007fd4728975f0 R08: 0000000000000ee3 R09: 00005555568904c0
R10: 0000000000000000 R11: 0000000000000246 R12: 00007fff91507d70
R13: 00007fff91507f98 R14: 431bde82d7b634db R15: 00007fd47286c03b
 </TASK>

The buggy address belongs to the physical page:
page: refcount:0 mapcount:0 mapping:0000000000000000 index:0x7f0a3df02 pfn:0x48f39
flags: 0x4fff00000000000(node=1|zone=1|lastcpupid=0x7ff)
raw: 04fff00000000000 ffffea000123ce88 ffff88801fc44cb0 0000000000000000
raw: 00000007f0a3df02 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 0x140dca(GFP_HIGHUSER_MOVABLE|__GFP_COMP|__GFP_ZERO), pid 5300, tgid 5300 (sshd), ts 68164329439, free_ts 68237870503
 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+0x303f/0x3190 mm/page_alloc.c:3457
 __alloc_pages_noprof+0x292/0x710 mm/page_alloc.c:4733
 alloc_pages_mpol_noprof+0x3e8/0x680 mm/mempolicy.c:2265
 folio_alloc_mpol_noprof mm/mempolicy.c:2283 [inline]
 vma_alloc_folio_noprof+0x12e/0x230 mm/mempolicy.c:2314
 folio_prealloc+0x31/0x170
 alloc_anon_folio mm/memory.c:4727 [inline]
 do_anonymous_page mm/memory.c:4784 [inline]
 do_pte_missing mm/memory.c:3963 [inline]
 handle_pte_fault+0x24dd/0x6820 mm/memory.c:5766
 __handle_mm_fault mm/memory.c:5909 [inline]
 handle_mm_fault+0x1106/0x1bb0 mm/memory.c:6077
 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 5300 tgid 5300 stack trace:
 reset_page_owner include/linux/page_owner.h:25 [inline]
 free_pages_prepare mm/page_alloc.c:1108 [inline]
 free_unref_folios+0xf12/0x18d0 mm/page_alloc.c:2686
 folios_put_refs+0x76c/0x860 mm/swap.c:1007
 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
 vms_clear_ptes+0x437/0x530 mm/vma.c:1103
 vms_complete_munmap_vmas+0x208/0x910 mm/vma.c:1147
 do_vmi_align_munmap+0x613/0x730 mm/vma.c:1356
 do_vmi_munmap+0x24e/0x2d0 mm/vma.c:1404
 __vm_munmap+0x24c/0x480 mm/mmap.c:1613
 __do_sys_munmap mm/mmap.c:1630 [inline]
 __se_sys_munmap mm/mmap.c:1627 [inline]
 __x64_sys_munmap+0x60/0x70 mm/mmap.c:1627
 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:
 ffff888048f38f00: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
 ffff888048f38f80: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
>ffff888048f39000: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
                      ^
 ffff888048f39080: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
 ffff888048f39100: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
==================================================================


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