[moderation] [ocfs2?] KASAN: use-after-free Read in ocfs2_duplicate_inline_data

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: e5d505e3664b Merge tag 'trace-v7.1-rc3' of git://git.kerne..
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=1713302e580000
kernel config: https://syzkaller.appspot.com/x/.config?x=7f195f6be48c12ec
dashboard link: https://syzkaller.appspot.com/bug?extid=9319607d839baa0ae70d
compiler: Debian clang version 21.1.8 (++20251221033036+2078da43e25a-1~exp1~20251221153213.50), Debian LLD 21.1.8
CC: [jl...@evilplan.org jose...@linux.alibaba.com linux-...@vger.kernel.org ma...@fasheh.com ocfs2...@lists.linux.dev]

Unfortunately, I don't have any reproducer for this issue yet.

Downloadable assets:
disk image (non-bootable): https://storage.googleapis.com/syzbot-assets/d900f083ada3/non_bootable_disk-e5d505e3.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/e34834fd8b3d/vmlinux-e5d505e3.xz
kernel image: https://storage.googleapis.com/syzbot-assets/83271095636f/bzImage-e5d505e3.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+931960...@syzkaller.appspotmail.com

==================================================================
BUG: KASAN: use-after-free in ocfs2_duplicate_inline_data+0x3ae/0x570 fs/ocfs2/refcounttree.c:3946
Read of size 8483 at addr ffff88800bbc56c8 by task syz.0.0/5335

CPU: 0 UID: 0 PID: 5335 Comm: syz.0.0 Not tainted syzkaller #0 PREEMPT(full)
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.3-debian-1.16.3-2 04/01/2014
Call Trace:
<TASK>
dump_stack_lvl+0xe8/0x150 lib/dump_stack.c:120
print_address_description+0x55/0x1e0 mm/kasan/report.c:378
print_report+0x58/0x70 mm/kasan/report.c:482
kasan_report+0x117/0x150 mm/kasan/report.c:595
check_region_inline mm/kasan/generic.c:-1 [inline]
kasan_check_range+0x264/0x2c0 mm/kasan/generic.c:200
__asan_memcpy+0x29/0x70 mm/kasan/shadow.c:105
ocfs2_duplicate_inline_data+0x3ae/0x570 fs/ocfs2/refcounttree.c:3946
ocfs2_reflink_remap_blocks+0xfcf/0x1a30 fs/ocfs2/refcounttree.c:4625
ocfs2_remap_file_range+0x451/0x6f0 fs/ocfs2/file.c:2747
vfs_copy_file_range+0xd80/0x1370 fs/read_write.c:1600
__do_sys_copy_file_range fs/read_write.c:1683 [inline]
__se_sys_copy_file_range+0x2fb/0x480 fs/read_write.c:1650
do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
do_syscall_64+0x15f/0xf80 arch/x86/entry/syscall_64.c:94
entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7feeb9d9ce59
Code: ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 44 00 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 e8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007feebacb8fe8 EFLAGS: 00000246 ORIG_RAX: 0000000000000146
RAX: ffffffffffffffda RBX: 00007feeba016090 RCX: 00007feeb9d9ce59
RDX: 0000000000000005 RSI: 00002000000001c0 RDI: 0000000000000006
RBP: 00007feeb9e32d6f R08: ffffffffa003e45b R09: 0700000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007feeba016128 R14: 00007feeba016090 R15: 00007ffccb81aac8
</TASK>

The buggy address belongs to the physical page:
page: refcount:2 mapcount:0 mapping:ffff88801cc25940 index:0x854 pfn:0xbbc5
memcg:ffff888036579480
aops:def_blk_aops ino:700000 dentry name(?):""
flags: 0xfff98000004224(referenced|lru|workingset|private|node=0|zone=1|lastcpupid=0x7ff)
raw: 00fff98000004224 ffff88801c6e5600 ffffea00004a7b48 ffff88801cc25940
raw: 0000000000000854 ffff888046e8c1d0 00000002ffffffff ffff888036579480
page dumped because: kasan: bad access detected
page_owner tracks the page as allocated
page last allocated via order 0, migratetype Movable, gfp_mask 0x148c48(GFP_NOFS|__GFP_MOVABLE|__GFP_NOFAIL|__GFP_COMP|__GFP_HARDWALL), pid 5334, tgid 5333 (syz.0.0), ts 85585712597, free_ts 85544039740
set_page_owner include/linux/page_owner.h:32 [inline]
post_alloc_hook+0x231/0x280 mm/page_alloc.c:1858
prep_new_page mm/page_alloc.c:1866 [inline]
get_page_from_freelist+0x24ba/0x2540 mm/page_alloc.c:3946
__alloc_frozen_pages_noprof+0x18d/0x380 mm/page_alloc.c:5226
alloc_pages_mpol+0x235/0x490 mm/mempolicy.c:2490
alloc_frozen_pages_noprof mm/mempolicy.c:2561 [inline]
alloc_pages_noprof+0xac/0x2a0 mm/mempolicy.c:2581
folio_alloc_noprof+0x1e/0x30 mm/mempolicy.c:2591
filemap_alloc_folio_noprof+0x111/0x470 mm/filemap.c:1014
__filemap_get_folio_mpol+0x3fc/0xb00 mm/filemap.c:2012
__filemap_get_folio include/linux/pagemap.h:763 [inline]
grow_dev_folio fs/buffer.c:954 [inline]
grow_buffers fs/buffer.c:1020 [inline]
__getblk_slow fs/buffer.c:1038 [inline]
bdev_getblk+0x1f6/0x6e0 fs/buffer.c:1358
__getblk include/linux/buffer_head.h:380 [inline]
sb_getblk include/linux/buffer_head.h:386 [inline]
ocfs2_read_blocks+0x56d/0x1530 fs/ocfs2/buffer_head_io.c:236
ocfs2_read_inode_block_full fs/ocfs2/inode.c:1745 [inline]
ocfs2_read_inode_block+0xec/0x1d0 fs/ocfs2/inode.c:1759
ocfs2_assign_bh fs/ocfs2/dlmglue.c:2415 [inline]
ocfs2_inode_lock_full_nested+0x2ac/0x1bd0 fs/ocfs2/dlmglue.c:2510
ocfs2_reflink_inodes_lock+0x489/0xc20 fs/ocfs2/refcounttree.c:4743
ocfs2_remap_file_range+0x236/0x6f0 fs/ocfs2/file.c:2721
vfs_copy_file_range+0xd80/0x1370 fs/read_write.c:1600
__do_sys_copy_file_range fs/read_write.c:1683 [inline]
__se_sys_copy_file_range+0x2fb/0x480 fs/read_write.c:1650
page last free pid 5338 tgid 5333 stack trace:
reset_page_owner include/linux/page_owner.h:25 [inline]
__free_pages_prepare mm/page_alloc.c:1402 [inline]
free_unref_folios+0xcec/0x1480 mm/page_alloc.c:3004
folios_put_refs+0x9ff/0xb40 mm/swap.c:1008
folio_batch_release include/linux/folio_batch.h:101 [inline]
mapping_try_invalidate+0x3c2/0x4c0 mm/truncate.c:579
loop_set_status+0x29b/0xe40 drivers/block/loop.c:1246
loop_set_status_old drivers/block/loop.c:1362 [inline]
lo_ioctl+0xce6/0x1fb0 drivers/block/loop.c:1551
blkdev_ioctl+0x5e3/0x740 block/ioctl.c:797
vfs_ioctl fs/ioctl.c:51 [inline]
__do_sys_ioctl fs/ioctl.c:597 [inline]
__se_sys_ioctl+0xfc/0x170 fs/ioctl.c:583
do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
do_syscall_64+0x15f/0xf80 arch/x86/entry/syscall_64.c:94
entry_SYSCALL_64_after_hwframe+0x77/0x7f

Memory state around the buggy address:
ffff88800bbc5f00: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
ffff88800bbc5f80: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
>ffff88800bbc6000: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
^
ffff88800bbc6080: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
ffff88800bbc6100: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
==================================================================


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