[v6.6] kernel BUG in direntry_check_right

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: 5fa4793a2d2d Linux 6.6.119
git tree: linux-6.6.y
console output: https://syzkaller.appspot.com/x/log.txt?x=14629922580000
kernel config: https://syzkaller.appspot.com/x/.config?x=691a6769a86ac817
dashboard link: https://syzkaller.appspot.com/bug?extid=243f2adea073f599cad2
compiler: Debian clang version 20.1.8 (++20250708063551+0c9f909b7976-1~exp1~20250708183702.136), Debian LLD 20.1.8

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

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/63699875f1dd/disk-5fa4793a.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/8506652fcb6f/vmlinux-5fa4793a.xz
kernel image: https://storage.googleapis.com/syzbot-assets/1b30ceed1710/bzImage-5fa4793a.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+243f2a...@syzkaller.appspotmail.com

------------[ cut here ]------------
kernel BUG at fs/reiserfs/item_ops.c:569!
invalid opcode: 0000 [#1] PREEMPT SMP KASAN
CPU: 0 PID: 6557 Comm: syz.4.115 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/25/2025
RIP: 0010:direntry_check_right+0x266/0x270 fs/reiserfs/item_ops.c:569
Code: e9 4b ff ff ff 44 89 f9 80 e1 07 38 c1 0f 8c 51 ff ff ff be 04 00 00 00 4c 89 ff e8 f4 f4 b4 ff e9 3f ff ff ff e8 1a 86 5d ff <0f> 0b e8 13 86 5d ff 0f 0b 90 f3 0f 1e fa 55 41 57 41 56 41 55 41
RSP: 0018:ffffc90003506cd8 EFLAGS: 00010293
RAX: ffffffff82280aa6 RBX: dffffc0000000000 RCX: ffff888018b89e00
RDX: 0000000000000000 RSI: 0000000000000020 RDI: 0000000000000044
RBP: ffff888079a680fe R08: ffff888018b89e00 R09: 0000000000000002
R10: 0000000000000070 R11: 0000000000000000 R12: ffff888079a680fe
R13: 0000000000000020 R14: 0000000000000000 R15: 0000000000000024
FS: 0000000000000000(0000) GS:ffff8880b8e00000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007face2744e9c CR3: 0000000068365000 CR4: 00000000003506f0
Call Trace:
<TASK>
check_right+0x4ea/0x7f0 fs/reiserfs/fix_node.c:355
dc_check_balance_leaf fs/reiserfs/fix_node.c:1983 [inline]
dc_check_balance fs/reiserfs/fix_node.c:2039 [inline]
check_balance fs/reiserfs/fix_node.c:2086 [inline]
fix_nodes+0x3dbb/0x82e0 fs/reiserfs/fix_node.c:2636
reiserfs_cut_from_item+0x309/0x1f10 fs/reiserfs/stree.c:1740
reiserfs_do_truncate+0xa3d/0x1340 fs/reiserfs/stree.c:1971
reiserfs_truncate_file+0x37a/0x7c0 fs/reiserfs/inode.c:2306
reiserfs_file_release+0x8e4/0xa50 fs/reiserfs/file.c:109
__fput+0x234/0x970 fs/file_table.c:384
task_work_run+0x1ce/0x250 kernel/task_work.c:239
exit_task_work include/linux/task_work.h:43 [inline]
do_exit+0x90b/0x23c0 kernel/exit.c:883
do_group_exit+0x21b/0x2d0 kernel/exit.c:1024
get_signal+0x12fc/0x1400 kernel/signal.c:2902
arch_do_signal_or_restart+0x9c/0x7b0 arch/x86/kernel/signal.c:310
exit_to_user_mode_loop+0x70/0x110 kernel/entry/common.c:174
exit_to_user_mode_prepare+0xf6/0x180 kernel/entry/common.c:210
irqentry_exit_to_user_mode+0x9/0x40 kernel/entry/common.c:315
exc_page_fault+0x8f/0x110 arch/x86/mm/fault.c:1524
asm_exc_page_fault+0x26/0x30 arch/x86/include/asm/idtentry.h:608
RIP: 0033:0x7f478c58f751
Code: Unable to access opcode bytes at 0x7f478c58f727.
RSP: 002b:fffffffffffffe70 EFLAGS: 00010217
RAX: 0000000000000000 RBX: 00007f478c7e6090 RCX: 00007f478c58f749
RDX: 0000000000000000 RSI: fffffffffffffe70 RDI: 0000000000008000
RBP: 00007f478c613f91 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000206 R12: 0000000000000000
R13: 00007f478c7e6128 R14: 00007f478c7e6090 R15: 00007ffdac88c0e8
</TASK>
Modules linked in:
---[ end trace 0000000000000000 ]---
RIP: 0010:direntry_check_right+0x266/0x270 fs/reiserfs/item_ops.c:569
Code: e9 4b ff ff ff 44 89 f9 80 e1 07 38 c1 0f 8c 51 ff ff ff be 04 00 00 00 4c 89 ff e8 f4 f4 b4 ff e9 3f ff ff ff e8 1a 86 5d ff <0f> 0b e8 13 86 5d ff 0f 0b 90 f3 0f 1e fa 55 41 57 41 56 41 55 41
RSP: 0018:ffffc90003506cd8 EFLAGS: 00010293
RAX: ffffffff82280aa6 RBX: dffffc0000000000 RCX: ffff888018b89e00
RDX: 0000000000000000 RSI: 0000000000000020 RDI: 0000000000000044
RBP: ffff888079a680fe R08: ffff888018b89e00 R09: 0000000000000002
R10: 0000000000000070 R11: 0000000000000000 R12: ffff888079a680fe
R13: 0000000000000020 R14: 0000000000000000 R15: 0000000000000024
FS: 0000000000000000(0000) GS:ffff8880b8e00000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007face2744e9c CR3: 0000000068365000 CR4: 00000000003506f0


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