[syzbot] [net?] WARNING: refcount bug in inet_twsk_kill

[syzbot <syzbot+8ea26396ff85d23a8929@syzkaller.appspotmail.com>]

Hello,

syzbot found the following issue on:

HEAD commit:    33e02dc69afb Merge tag 'sound-6.10-rc1' of git://git.kerne..
git tree:       upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=117f3182980000
kernel config:  https://syzkaller.appspot.com/x/.config?x=25544a2faf4bae65
dashboard link: https://syzkaller.appspot.com/bug?extid=8ea26396ff85d23a8929
compiler:       gcc (Debian 12.2.0-14) 12.2.0, 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/7bc7510fe41f/non_bootable_disk-33e02dc6.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/573c88ac3233/vmlinux-33e02dc6.xz
kernel image: https://storage.googleapis.com/syzbot-assets/760a52b9a00a/bzImage-33e02dc6.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+8ea26396ff85d23a8929@syzkaller.appspotmail.com

------------[ cut here ]------------
refcount_t: decrement hit 0; leaking memory.
WARNING: CPU: 3 PID: 1396 at lib/refcount.c:31 refcount_warn_saturate+0x1ed/0x210 lib/refcount.c:31
Modules linked in:
CPU: 3 PID: 1396 Comm: syz-executor.3 Not tainted 6.9.0-syzkaller-07370-g33e02dc69afb #0
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.2-debian-1.16.2-1 04/01/2014
RIP: 0010:refcount_warn_saturate+0x1ed/0x210 lib/refcount.c:31
Code: 8b e8 37 85 cf fc 90 0f 0b 90 90 e9 c3 fe ff ff e8 68 34 0d fd c6 05 0d 81 4c 0b 01 90 48 c7 c7 20 2b 8f 8b e8 14 85 cf fc 90 <0f> 0b 90 90 e9 a0 fe ff ff 48 89 ef e8 e2 e8 68 fd e9 44 fe ff ff
RSP: 0018:ffffc9000480fa70 EFLAGS: 00010282
RAX: 0000000000000000 RBX: 0000000000000000 RCX: ffffc9002ce28000
RDX: 0000000000040000 RSI: ffffffff81505406 RDI: 0000000000000001
RBP: ffff88804d8b3f80 R08: 0000000000000001 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000002 R12: ffff88804d8b3f80
R13: ffff888031c601c0 R14: ffffc900013c04f8 R15: 000000002a3e5567
FS:  00007f56d897c6c0(0000) GS:ffff88806b300000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000001b3182b000 CR3: 0000000034ed6000 CR4: 0000000000350ef0
Call Trace:
 <TASK>
 __refcount_dec include/linux/refcount.h:336 [inline]
 refcount_dec include/linux/refcount.h:351 [inline]
 inet_twsk_kill+0x758/0x9c0 net/ipv4/inet_timewait_sock.c:70
 inet_twsk_deschedule_put net/ipv4/inet_timewait_sock.c:221 [inline]
 inet_twsk_purge+0x725/0x890 net/ipv4/inet_timewait_sock.c:304
 tcp_twsk_purge+0x115/0x150 net/ipv4/tcp_minisocks.c:402
 tcp_sk_exit_batch+0x1c/0x170 net/ipv4/tcp_ipv4.c:3522
 ops_exit_list+0x128/0x180 net/core/net_namespace.c:178
 setup_net+0x714/0xb40 net/core/net_namespace.c:375
 copy_net_ns+0x2f0/0x670 net/core/net_namespace.c:508
 create_new_namespaces+0x3ea/0xb10 kernel/nsproxy.c:110
 unshare_nsproxy_namespaces+0xc0/0x1f0 kernel/nsproxy.c:228
 ksys_unshare+0x419/0x970 kernel/fork.c:3323
 __do_sys_unshare kernel/fork.c:3394 [inline]
 __se_sys_unshare kernel/fork.c:3392 [inline]
 __x64_sys_unshare+0x31/0x40 kernel/fork.c:3392
 do_syscall_x64 arch/x86/entry/common.c:52 [inline]
 do_syscall_64+0xcf/0x260 arch/x86/entry/common.c:83
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f56d7c7cee9
Code: 28 00 00 00 75 05 48 83 c4 28 c3 e8 e1 20 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:00007f56d897c0c8 EFLAGS: 00000246 ORIG_RAX: 0000000000000110
RAX: ffffffffffffffda RBX: 00007f56d7dac1f0 RCX: 00007f56d7c7cee9
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000042000000
RBP: 00007f56d7cc949e R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 000000000000006e R14: 00007f56d7dac1f0 R15: 00007ffe66454be8
 </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@googlegroups.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