linux-kernel - [syzbot] [btrfs?] kernel BUG in btrfs_backref_release

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives
Hash Suite for Android: free password hash cracker in your pocket
[<prev] [next>] [day] [month] [year] [list]
Message-ID: <67b8c338.050a0220.14d86d.0594.GAE@google.com>
Date: Fri, 21 Feb 2025 10:17:28 -0800
From: syzbot <syzbot+1de7265d1e4c0c19dd35@...kaller.appspotmail.com>
To: clm@...com, dsterba@...e.com, josef@...icpanda.com, 
	linux-btrfs@...r.kernel.org, linux-kernel@...r.kernel.org, 
	syzkaller-bugs@...glegroups.com
Subject: [syzbot] [btrfs?] kernel BUG in btrfs_backref_release_cache

Hello,

syzbot found the following issue on:

HEAD commit:    0ad2507d5d93 Linux 6.14-rc3
git tree:       upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=14b775a4580000
kernel config:  https://syzkaller.appspot.com/x/.config?x=b7bde34acd8f53b1
dashboard link: https://syzkaller.appspot.com/bug?extid=1de7265d1e4c0c19dd35
compiler:       Debian clang version 15.0.6, GNU ld (GNU Binutils for Debian) 2.40

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

Downloadable assets:
disk image (non-bootable): https://storage.googleapis.com/syzbot-assets/7feb34a89c2a/non_bootable_disk-0ad2507d.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/dfb4fc7c042e/vmlinux-0ad2507d.xz
kernel image: https://storage.googleapis.com/syzbot-assets/1682113b81f5/bzImage-0ad2507d.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+1de7265d1e4c0c19dd35@...kaller.appspotmail.com

loop0: detected capacity change from 0 to 32768
BTRFS: device fsid ed167579-eb65-4e76-9a50-61ac97e9b59d devid 1 transid 8 /dev/loop0 (7:0) scanned by syz.0.0 (5320)
BTRFS info (device loop0): first mount of filesystem ed167579-eb65-4e76-9a50-61ac97e9b59d
BTRFS info (device loop0): using sha256 (sha256-avx2) checksum algorithm
BTRFS info (device loop0): rebuilding free space tree
BTRFS info (device loop0): disabling free space tree
BTRFS info (device loop0): clearing compat-ro feature flag for FREE_SPACE_TREE (0x1)
BTRFS info (device loop0): clearing compat-ro feature flag for FREE_SPACE_TREE_VALID (0x2)
BTRFS info (device loop0): balance: start -d -m
BTRFS info (device loop0): relocating block group 6881280 flags data|metadata
BTRFS info (device loop0): relocating block group 5242880 flags data|metadata
BTRFS info (device loop0): found 139 extents, stage: move data extents
assertion failed: !cache->nr_nodes, in fs/btrfs/backref.c:3160
------------[ cut here ]------------
kernel BUG at fs/btrfs/backref.c:3160!
Oops: invalid opcode: 0000 [#1] PREEMPT SMP KASAN NOPTI
CPU: 0 UID: 0 PID: 5320 Comm: syz.0.0 Not tainted 6.14.0-rc3-syzkaller #0
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.3-debian-1.16.3-2~bpo12+1 04/01/2014
RIP: 0010:btrfs_backref_release_cache+0x1b5/0x1e0 fs/btrfs/backref.c:3160
Code: 23 fd 90 0f 0b e8 db 93 be fd 48 c7 c7 a0 ea 6d 8c 48 c7 c6 40 f3 6d 8c 48 c7 c2 40 eb 6d 8c b9 58 0c 00 00 e8 fc e1 23 fd 90 <0f> 0b e8 b4 93 be fd 48 c7 c7 a0 ea 6d 8c 48 c7 c6 80 f3 6d 8c 48
RSP: 0018:ffffc9000d457838 EFLAGS: 00010246
RAX: 000000000000003e RBX: 0000000000000002 RCX: 83d820ae1486a200
RDX: 0000000000000000 RSI: 0000000080000000 RDI: 0000000000000000
RBP: ffffc9000d457a00 R08: ffffffff81a1108c R09: 1ffff92001a8aea4
R10: dffffc0000000000 R11: fffff52001a8aea5 R12: dffffc0000000000
R13: dffffc0000000000 R14: ffff888052f880f0 R15: ffff888052f88020
FS:  00007fb48b6ac6c0(0000) GS:ffff88801fc00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000000000000000 CR3: 0000000044042000 CR4: 0000000000352ef0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 <TASK>
 relocate_block_group+0xabf/0xd40 fs/btrfs/relocation.c:3664
 btrfs_relocate_block_group+0x77d/0xd90 fs/btrfs/relocation.c:4009
 btrfs_relocate_chunk+0x12c/0x3b0 fs/btrfs/volumes.c:3511
 __btrfs_balance+0x1b0f/0x26b0 fs/btrfs/volumes.c:4292
 btrfs_balance+0xbdc/0x10c0 fs/btrfs/volumes.c:4669
 btrfs_ioctl_balance+0x3f5/0x660 fs/btrfs/ioctl.c:3587
 vfs_ioctl fs/ioctl.c:51 [inline]
 __do_sys_ioctl fs/ioctl.c:906 [inline]
 __se_sys_ioctl+0xf5/0x170 fs/ioctl.c:892
 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: 0033:0x7fb48a78cde9
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:00007fb48b6ac038 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 00007fb48a9a5fa0 RCX: 00007fb48a78cde9
RDX: 0000400000000180 RSI: 00000000c4009420 RDI: 0000000000000004
RBP: 00007fb48a80e2a0 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 0000000000000000 R14: 00007fb48a9a5fa0 R15: 00007ffedc7a6988
 </TASK>
Modules linked in:
---[ end trace 0000000000000000 ]---
RIP: 0010:btrfs_backref_release_cache+0x1b5/0x1e0 fs/btrfs/backref.c:3160
Code: 23 fd 90 0f 0b e8 db 93 be fd 48 c7 c7 a0 ea 6d 8c 48 c7 c6 40 f3 6d 8c 48 c7 c2 40 eb 6d 8c b9 58 0c 00 00 e8 fc e1 23 fd 90 <0f> 0b e8 b4 93 be fd 48 c7 c7 a0 ea 6d 8c 48 c7 c6 80 f3 6d 8c 48
RSP: 0018:ffffc9000d457838 EFLAGS: 00010246
RAX: 000000000000003e RBX: 0000000000000002 RCX: 83d820ae1486a200
RDX: 0000000000000000 RSI: 0000000080000000 RDI: 0000000000000000
RBP: ffffc9000d457a00 R08: ffffffff81a1108c R09: 1ffff92001a8aea4
R10: dffffc0000000000 R11: fffff52001a8aea5 R12: dffffc0000000000
R13: dffffc0000000000 R14: ffff888052f880f0 R15: ffff888052f88020
FS:  00007fb48b6ac6c0(0000) GS:ffff88801fc00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 000055dd4cdc80e8 CR3: 0000000044042000 CR4: 0000000000352ef0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400


---
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.

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

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