Re: [syzbot] [jfs?] kernel BUG in jfs_unlink

[syzbot <syzbot+41b43444de86db4c5ed1@syzkaller.appspotmail.com>]

syzbot has found a reproducer for the following issue on:

HEAD commit:    c9f016e72b5c Merge tag 'x86-urgent-2024-09-01' of git://gi..
git tree:       upstream
console+strace: https://syzkaller.appspot.com/x/log.txt?x=14d09929980000
kernel config:  https://syzkaller.appspot.com/x/.config?x=8926d683f62db53e
dashboard link: https://syzkaller.appspot.com/bug?extid=41b43444de86db4c5ed1
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=106934fb980000
C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=15617f2f980000

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/e47617e91522/disk-c9f016e7.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/69d8aef7dff1/vmlinux-c9f016e7.xz
kernel image: https://storage.googleapis.com/syzbot-assets/dd5392c61560/bzImage-c9f016e7.xz
mounted in repro: https://storage.googleapis.com/syzbot-assets/7111d4efcae8/mount_0.gz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+41b43444de86db4c5ed1@syzkaller.appspotmail.com

BUG at fs/jfs/namei.c:513 assert(ip->i_nlink)
------------[ cut here ]------------
kernel BUG at fs/jfs/namei.c:513!
Oops: invalid opcode: 0000 [#1] PREEMPT SMP KASAN PTI
CPU: 1 UID: 0 PID: 5224 Comm: syz-executor204 Not tainted 6.11.0-rc6-syzkaller-00017-gc9f016e72b5c #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 08/06/2024
RIP: 0010:jfs_unlink+0xafd/0xb30 fs/jfs/namei.c:513
Code: e8 c8 5d 91 08 e8 83 f0 73 fe 48 c7 c7 20 9c 22 8c 48 c7 c6 e0 99 22 8c ba 01 02 00 00 48 c7 c1 60 9c 22 8c e8 64 5e 8e 08 90 <0f> 0b e8 5c f0 73 fe 48 c7 c7 20 9c 22 8c 48 c7 c6 e0 99 22 8c ba
RSP: 0018:ffffc9000344fbe0 EFLAGS: 00010246
RAX: 000000000000002d RBX: 0000000000000000 RCX: 44cfc770ad800100
RDX: 0000000000000000 RSI: 0000000080000000 RDI: 0000000000000000
RBP: ffffc9000344fd10 R08: ffffffff8174016c R09: 1ffff92000689f1c
R10: dffffc0000000000 R11: fffff52000689f1d R12: 0000000000000000
R13: ffffc9000344fc60 R14: 1ffff92000689f8c R15: ffff888072c33248
FS:  0000555577bcd380(0000) GS:ffff8880b8900000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 000000000045bdd0 CR3: 000000007ab8a000 CR4: 00000000003506f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 <TASK>
 vfs_unlink+0x365/0x650 fs/namei.c:4422
 do_unlinkat+0x4ae/0x830 fs/namei.c:4486
 __do_sys_unlink fs/namei.c:4534 [inline]
 __se_sys_unlink fs/namei.c:4532 [inline]
 __x64_sys_unlink+0x47/0x50 fs/namei.c:4532
 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: 0033:0x7f69ef25fad7
Code: 73 01 c3 48 c7 c1 b8 ff ff ff f7 d8 64 89 01 48 83 c8 ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 44 00 00 b8 57 00 00 00 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 b8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007fff4544dac8 EFLAGS: 00000206 ORIG_RAX: 0000000000000057
RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 00007f69ef25fad7
RDX: 00007fff4544daf0 RSI: 00007fff4544db80 RDI: 00007fff4544db80
RBP: 00007fff4544db80 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000100 R11: 0000000000000206 R12: 00007fff4544ec70
R13: 0000555577bd6700 R14: 0000000000000001 R15: 431bde82d7b634db
 </TASK>
Modules linked in:
---[ end trace 0000000000000000 ]---
RIP: 0010:jfs_unlink+0xafd/0xb30 fs/jfs/namei.c:513
Code: e8 c8 5d 91 08 e8 83 f0 73 fe 48 c7 c7 20 9c 22 8c 48 c7 c6 e0 99 22 8c ba 01 02 00 00 48 c7 c1 60 9c 22 8c e8 64 5e 8e 08 90 <0f> 0b e8 5c f0 73 fe 48 c7 c7 20 9c 22 8c 48 c7 c6 e0 99 22 8c ba
RSP: 0018:ffffc9000344fbe0 EFLAGS: 00010246
RAX: 000000000000002d RBX: 0000000000000000 RCX: 44cfc770ad800100
RDX: 0000000000000000 RSI: 0000000080000000 RDI: 0000000000000000
RBP: ffffc9000344fd10 R08: ffffffff8174016c R09: 1ffff92000689f1c
R10: dffffc0000000000 R11: fffff52000689f1d R12: 0000000000000000
R13: ffffc9000344fc60 R14: 1ffff92000689f8c R15: ffff888072c33248
FS:  0000555577bcd380(0000) GS:ffff8880b8900000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 000000000045bdd0 CR3: 000000007ab8a000 CR4: 00000000003506f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400


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