Subject: [syzbot] [net?] WARNING in cleanup_net (3)

From: syzbot <[email-masked]>
Date: Thu, 30 Nov 2023 00:30:17 -0800

Hello,

syzbot found the following issue on:

HEAD commit:    d90b0276af8f Merge tag 'hardening-v6.6-rc3' of git://git.k..
git tree:       upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=12c4675c680000
kernel config:  https://syzkaller.appspot.com/x/.config?x=d594086f139d167
dashboard link: https://syzkaller.appspot.com/bug?extid=9ada62e1dc03fdc41982
compiler:       gcc (Debian 12.2.0-14) 12.2.0, GNU ld (GNU Binutils for Debian) 2.40
userspace arch: i386

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-d90b0276.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/c6997ebf3cf3/vmlinux-d90b0276.xz
kernel image: https://storage.googleapis.com/syzbot-assets/d893c5c3f98f/bzImage-d90b0276.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: [email-masked]

     do_fast_syscall_32+0x33/0x70 arch/x86/entry/common.c:203
     entry_SYSENTER_compat_after_hwframe+0x70/0x82
------------[ cut here ]------------
WARNING: CPU: 1 PID: 1093 at lib/ref_tracker.c:179 spin_unlock_irqrestore include/linux/spinlock.h:406 [inline]
WARNING: CPU: 1 PID: 1093 at lib/ref_tracker.c:179 ref_tracker_dir_exit+0x3e2/0x680 lib/ref_tracker.c:178
Modules linked in:
CPU: 1 PID: 1093 Comm: kworker/u16:7 Not tainted 6.6.0-rc2-syzkaller-00337-gd90b0276af8f #0
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.2-debian-1.16.2-1 04/01/2014
Workqueue: netns cleanup_net
RIP: 0010:ref_tracker_dir_exit+0x3e2/0x680 lib/ref_tracker.c:179
Code: 85 07 02 00 00 4d 39 f5 49 8b 06 4d 89 f7 0f 85 0e ff ff ff 48 8b 2c 24 e8 4b 7b 32 fd 48 8b 74 24 18 48 89 ef e8 ce d8 ec 05 <0f> 0b e8 37 7b 32 fd 48 8d 5d 44 be 04 00 00 00 48 89 df e8 b6 34
RSP: 0018:ffffc90006ee7b78 EFLAGS: 00010246
RAX: 0000000000000000 RBX: dffffc0000000000 RCX: 0000000000000000
RDX: 0000000000000001 RSI: ffffffff8a8cab20 RDI: 0000000000000001
RBP: ffff8880591981e0 R08: 0000000000000001 R09: fffffbfff233dff7
R10: ffffffff919effbf R11: 0000000000000114 R12: ffff888059198230
R13: ffff888059198230 R14: ffff888059198230 R15: ffff888059198230
FS:  0000000000000000(0000) GS:ffff88802c700000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000000057ab404c CR3: 0000000070f05000 CR4: 0000000000350ee0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 00000000ffff00f1 DR6: 00000000ffff0ff0 DR7: 0000000000000400
Call Trace:
 <TASK>
 net_free net/core/net_namespace.c:448 [inline]
 net_free net/core/net_namespace.c:442 [inline]
 cleanup_net+0x8d4/0xb20 net/core/net_namespace.c:635
 process_one_work+0x884/0x15c0 kernel/workqueue.c:2630
 process_scheduled_works kernel/workqueue.c:2703 [inline]
 worker_thread+0x8b9/0x1290 kernel/workqueue.c:2784
 kthread+0x33c/0x440 kernel/kthread.c:388
 ret_from_fork+0x45/0x80 arch/x86/kernel/process.c:147
 ret_from_fork_asm+0x11/0x20 arch/x86/entry/entry_64.S:304
 </TASK>

---
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