Message-ID: <68811963.050a0220.248954.0005.GAE@google.com>
Date: Wed, 23 Jul 2025 10:18:27 -0700
From: syzbot <syzbot+41ba9c82bce8d7101765@...kaller.appspotmail.com>
To: frank.li@...o.com, glaubitz@...sik.fu-berlin.de, 
	linux-fsdevel@...r.kernel.org, linux-kernel@...r.kernel.org, 
	slava@...eyko.com, syzkaller-bugs@...glegroups.com
Subject: [syzbot] [hfs?] KASAN: out-of-bounds Read in hfs_bnode_move

Hello,

syzbot found the following issue on:

HEAD commit:    89be9a83ccf1 Linux 6.16-rc7
git tree:       upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=17ac1b82580000
kernel config:  https://syzkaller.appspot.com/x/.config?x=8adfe52da0de2761
dashboard link: https://syzkaller.appspot.com/bug?extid=41ba9c82bce8d7101765
compiler:       Debian clang version 20.1.7 (++20250616065708+6146a88f6049-1~exp1~20250616065826.132), Debian LLD 20.1.7
syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=1771ef22580000
C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=11f764f0580000

Downloadable assets:
disk image (non-bootable): https://storage.googleapis.com/syzbot-assets/d900f083ada3/non_bootable_disk-89be9a83.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/a3f5f507f252/vmlinux-89be9a83.xz
kernel image: https://storage.googleapis.com/syzbot-assets/a8f9b92c57a6/bzImage-89be9a83.xz
mounted in repro: https://storage.googleapis.com/syzbot-assets/f02d92e4771f/mount_0.gz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+41ba9c82bce8d7101765@...kaller.appspotmail.com

loop0: detected capacity change from 0 to 64
==================================================================
BUG: KASAN: out-of-bounds in hfs_bnode_move+0xea/0x130 fs/hfs/bnode.c:143
Read of size 18446744073709486080 at addr ffff888000994400 by task syz.0.16/5547

CPU: 0 UID: 0 PID: 5547 Comm: syz.0.16 Not tainted 6.16.0-rc7-syzkaller #0 PREEMPT(full) 
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_lvl+0x189/0x250 lib/dump_stack.c:120
 print_address_description mm/kasan/report.c:378 [inline]
 print_report+0xca/0x230 mm/kasan/report.c:480
 kasan_report+0x118/0x150 mm/kasan/report.c:593
 check_region_inline mm/kasan/generic.c:-1 [inline]
 kasan_check_range+0x2b0/0x2c0 mm/kasan/generic.c:189
 __asan_memmove+0x29/0x70 mm/kasan/shadow.c:94
 hfs_bnode_move+0xea/0x130 fs/hfs/bnode.c:143
 hfs_brec_remove+0x467/0x550 fs/hfs/brec.c:222
 hfs_cat_move+0x6fb/0x960 fs/hfs/catalog.c:364
 hfs_rename+0x1dc/0x2d0 fs/hfs/dir.c:299
 vfs_rename+0xb99/0xec0 fs/namei.c:5137
 do_renameat2+0x878/0xc50 fs/namei.c:5286
 __do_sys_rename fs/namei.c:5333 [inline]
 __se_sys_rename fs/namei.c:5331 [inline]
 __x64_sys_rename+0x82/0x90 fs/namei.c:5331
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xfa/0x3b0 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f11db18e9a9
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:00007ffd56ec9fe8 EFLAGS: 00000246 ORIG_RAX: 0000000000000052
RAX: ffffffffffffffda RBX: 00007f11db3b5fa0 RCX: 00007f11db18e9a9
RDX: 0000000000000000 RSI: 0000200000000780 RDI: 00002000000003c0
RBP: 00007f11db210d69 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f11db3b5fa0 R14: 00007f11db3b5fa0 R15: 0000000000000002
 </TASK>

The buggy address belongs to the physical page:
page: refcount:1 mapcount:0 mapping:0000000000000000 index:0x35 pfn:0x994
memcg:ffff888030a98000
anon flags: 0x7ff00000020908(uptodate|active|owner_2|swapbacked|node=0|zone=0|lastcpupid=0x7ff)
raw: 007ff00000020908 0000000000000000 dead000000000122 ffff888059a96cc1
raw: 0000000000000035 0000000000000000 00000001ffffffff ffff888030a98000
page dumped because: kasan: bad access detected
page_owner tracks the page as allocated
page last allocated via order 0, migratetype Movable, gfp_mask 0x140cca(GFP_HIGHUSER_MOVABLE|__GFP_COMP), pid 5548, tgid 5548 (dhcpcd-run-hook), ts 123108746961, free_ts 121368908469
 set_page_owner include/linux/page_owner.h:32 [inline]
 post_alloc_hook+0x240/0x2a0 mm/page_alloc.c:1704
 prep_new_page mm/page_alloc.c:1712 [inline]
 get_page_from_freelist+0x21e4/0x22c0 mm/page_alloc.c:3669
 __alloc_frozen_pages_noprof+0x181/0x370 mm/page_alloc.c:4959
 alloc_pages_mpol+0x232/0x4a0 mm/mempolicy.c:2419
 folio_alloc_mpol_noprof mm/mempolicy.c:2438 [inline]
 vma_alloc_folio_noprof+0xe4/0x200 mm/mempolicy.c:2473
 folio_prealloc+0x30/0x180 mm/memory.c:-1
 wp_page_copy mm/memory.c:3569 [inline]
 do_wp_page+0x1231/0x5800 mm/memory.c:4030
 handle_pte_fault mm/memory.c:6085 [inline]
 __handle_mm_fault+0x1144/0x5620 mm/memory.c:6212
 handle_mm_fault+0x40a/0x8e0 mm/memory.c:6381
 do_user_addr_fault+0xa81/0x1390 arch/x86/mm/fault.c:1336
 handle_page_fault arch/x86/mm/fault.c:1476 [inline]
 exc_page_fault+0x76/0xf0 arch/x86/mm/fault.c:1532
 asm_exc_page_fault+0x26/0x30 arch/x86/include/asm/idtentry.h:623
page last free pid 5509 tgid 5509 stack trace:
 reset_page_owner include/linux/page_owner.h:25 [inline]
 free_pages_prepare mm/page_alloc.c:1248 [inline]
 free_unref_folios+0xc66/0x14d0 mm/page_alloc.c:2763
 folios_put_refs+0x559/0x640 mm/swap.c:992
 free_pages_and_swap_cache+0x4be/0x520 mm/swap_state.c:267
 __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:397 [inline]
 tlb_flush_mmu+0x3a0/0x680 mm/mmu_gather.c:404
 tlb_finish_mmu+0xc3/0x1d0 mm/mmu_gather.c:497
 exit_mmap+0x44c/0xb50 mm/mmap.c:1297
 __mmput+0x118/0x420 kernel/fork.c:1121
 exit_mm+0x1da/0x2c0 kernel/exit.c:581
 do_exit+0x648/0x22e0 kernel/exit.c:952
 do_group_exit+0x21c/0x2d0 kernel/exit.c:1105
 __do_sys_exit_group kernel/exit.c:1116 [inline]
 __se_sys_exit_group kernel/exit.c:1114 [inline]
 __x64_sys_exit_group+0x3f/0x40 kernel/exit.c:1114
 x64_sys_call+0x21ba/0x21c0 arch/x86/include/generated/asm/syscalls_64.h:232
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xfa/0x3b0 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

Memory state around the buggy address:
 ffff888000994300: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
 ffff888000994380: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
>ffff888000994400: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
                   ^
 ffff888000994480: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
 ffff888000994500: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
==================================================================


---
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