linux-kernel - [syzbot] [bfs?] WARNING in bfs

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Message-ID: <6776b5fb.050a0220.3a8527.0043.GAE@google.com>
Date: Thu, 02 Jan 2025 07:51:23 -0800
From: syzbot <syzbot+80e60df48923e1b7691d@...kaller.appspotmail.com>
To: aivazian.tigran@...il.com, linux-kernel@...r.kernel.org, 
	syzkaller-bugs@...glegroups.com
Subject: [syzbot] [bfs?] WARNING in bfs_rename

Hello,

syzbot found the following issue on:

HEAD commit:    8155b4ef3466 Add linux-next specific files for 20241220
git tree:       linux-next
console+strace: https://syzkaller.appspot.com/x/log.txt?x=17d8a818580000
kernel config:  https://syzkaller.appspot.com/x/.config?x=9c90bb7161a56c88
dashboard link: https://syzkaller.appspot.com/bug?extid=80e60df48923e1b7691d
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=167acac4580000
C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=1489b0b0580000

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/98a974fc662d/disk-8155b4ef.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/2dea9b72f624/vmlinux-8155b4ef.xz
kernel image: https://storage.googleapis.com/syzbot-assets/593a42b9eb34/bzImage-8155b4ef.xz
mounted in repro: https://storage.googleapis.com/syzbot-assets/8542e0b88fbf/mount_0.gz

Bisection is inconclusive: the issue happens on the oldest tested release.

bisection log:  https://syzkaller.appspot.com/x/bisect.txt?x=160f5818580000
final oops:     https://syzkaller.appspot.com/x/report.txt?x=150f5818580000
console output: https://syzkaller.appspot.com/x/log.txt?x=110f5818580000

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+80e60df48923e1b7691d@...kaller.appspotmail.com

------------[ cut here ]------------
WARNING: CPU: 0 PID: 5833 at fs/inode.c:407 drop_nlink+0xc4/0x110 fs/inode.c:407
Modules linked in:
CPU: 0 UID: 0 PID: 5833 Comm: syz-executor420 Not tainted 6.13.0-rc3-next-20241220-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 09/13/2024
RIP: 0010:drop_nlink+0xc4/0x110 fs/inode.c:407
Code: bb 70 07 00 00 be 08 00 00 00 e8 87 15 e7 ff f0 48 ff 83 70 07 00 00 5b 41 5c 41 5e 41 5f 5d c3 cc cc cc cc e8 4d 97 80 ff 90 <0f> 0b 90 eb 83 44 89 e1 80 e1 07 80 c1 03 38 c1 0f 8c 5c ff ff ff
RSP: 0018:ffffc90003e7f950 EFLAGS: 00010293
RAX: ffffffff823e8cd3 RBX: 1ffff1100e6a81f8 RCX: ffff8880347b3c00
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000000
RBP: 0000000000000000 R08: ffffffff823e8c53 R09: 1ffffffff203563e
R10: dffffc0000000000 R11: fffffbfff203563f R12: ffff888073540fc0
R13: dffffc0000000000 R14: ffff888073540f78 R15: dffffc0000000000
FS:  00007f7f45f236c0(0000) GS:ffff8880b8600000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00005574822450d8 CR3: 0000000029caa000 CR4: 00000000003526f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 <TASK>
 inode_dec_link_count include/linux/fs.h:2567 [inline]
 bfs_rename+0x44e/0x530 fs/bfs/dir.c:247
 vfs_rename+0xbdb/0xf00 fs/namei.c:5067
 do_renameat2+0xd94/0x13f0 fs/namei.c:5224
 __do_sys_rename fs/namei.c:5271 [inline]
 __se_sys_rename fs/namei.c:5269 [inline]
 __x64_sys_rename+0x82/0x90 fs/namei.c:5269
 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: 0033:0x7f7f45f6b569
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 b0 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007f7f45f23218 EFLAGS: 00000246 ORIG_RAX: 0000000000000052
RAX: ffffffffffffffda RBX: 00007f7f45ff26a8 RCX: 00007f7f45f6b569
RDX: ffffffffffffffb0 RSI: 0000000020000240 RDI: 00000000200001c0
RBP: 00007f7f45ff26a0 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000073 R11: 0000000000000246 R12: 00007f7f45fbf080
R13: 0030656c69662f2e R14: 00007f7f45fbf047 R15: c21418431439518c
 </TASK>


---
This report is generated by a bot. It may contain errors.
See https://goo.gl/tpsmEJ for more information about syzbot.
syzbot engineers can be reached at syzkaller@...glegroups.com.

syzbot will keep track of this issue. See:
https://goo.gl/tpsmEJ#status for how to communicate with syzbot.
For information about bisection process see: https://goo.gl/tpsmEJ#bisection

If the report is already addressed, let syzbot know by replying with:
#syz fix: exact-commit-title

If you want syzbot to run the reproducer, reply with:
#syz test: git://repo/address.git branch-or-commit-hash
If you attach or paste a git patch, syzbot will apply it before testing.

If you want to overwrite report's subsystems, reply with:
#syz set subsystems: new-subsystem
(See the list of subsystem names on the web dashboard)

If the report is a duplicate of another one, reply with:
#syz dup: exact-subject-of-another-report

If you want to undo deduplication, reply with:
#syz undup