| 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
| ||
|
Message-ID: <CAL+tcoB0as6+5VOk9nu0M_OH4TqT6NjDZBZmgQgdQcYx0pciCw@mail.gmail.com>
Date: Wed, 25 Jun 2025 21:44:16 +0800
From: Jason Xing <kerneljasonxing@...il.com>
To: syzbot <syzbot+e67ea9c235b13b4f0020@...kaller.appspotmail.com>
Cc: andrii@...nel.org, ast@...nel.org, bjorn@...nel.org, bpf@...r.kernel.org,
daniel@...earbox.net, davem@...emloft.net, edumazet@...gle.com,
horms@...nel.org, jonathan.lemon@...il.com, kuba@...nel.org,
linux-kernel@...r.kernel.org, maciej.fijalkowski@...el.com,
magnus.karlsson@...el.com, netdev@...r.kernel.org, pabeni@...hat.com,
sdf@...ichev.me, syzkaller-bugs@...glegroups.com
Subject: Re: [syzbot] [bpf?] [net?] possible deadlock in xsk_notifier (3)
On Wed, Jun 25, 2025 at 2:51 AM syzbot
<syzbot+e67ea9c235b13b4f0020@...kaller.appspotmail.com> wrote:
>
> Hello,
>
> syzbot found the following issue on:
>
> HEAD commit: 78f4e737a53e Merge tag 'for-6.16/dm-fixes' of git://git.ke..
> git tree: upstream
> console output: https://syzkaller.appspot.com/x/log.txt?x=11b48f0c580000
> kernel config: https://syzkaller.appspot.com/x/.config?x=12ec1a20ad573841
> dashboard link: https://syzkaller.appspot.com/bug?extid=e67ea9c235b13b4f0020
> 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: https://storage.googleapis.com/syzbot-assets/3ff97b2d201b/disk-78f4e737.raw.xz
> vmlinux: https://storage.googleapis.com/syzbot-assets/1968f46c8915/vmlinux-78f4e737.xz
> kernel image: https://storage.googleapis.com/syzbot-assets/3455e371b965/bzImage-78f4e737.xz
>
> IMPORTANT: if you fix the issue, please add the following tag to the commit:
> Reported-by: syzbot+e67ea9c235b13b4f0020@...kaller.appspotmail.com
>
> netlink: 4 bytes leftover after parsing attributes in process `syz.1.1331'.
> ======================================================
> WARNING: possible circular locking dependency detected
> 6.16.0-rc3-syzkaller-00042-g78f4e737a53e #0 Not tainted
> ------------------------------------------------------
> syz.1.1331/11144 is trying to acquire lock:
> ffff888054b136b0 (&xs->mutex){+.+.}-{4:4}, at: xsk_notifier+0x101/0x280 net/xdp/xsk.c:1649
>
> but task is already holding lock:
> ffff888052f43d58 (&net->xdp.lock){+.+.}-{4:4}, at: xsk_notifier+0xa4/0x280 net/xdp/xsk.c:1645
>
> which lock already depends on the new lock.
>
>
> the existing dependency chain (in reverse order) is:
>
> -> #2 (&net->xdp.lock){+.+.}-{4:4}:
> __mutex_lock_common kernel/locking/mutex.c:602 [inline]
> __mutex_lock+0x199/0xb90 kernel/locking/mutex.c:747
> xsk_notifier+0xa4/0x280 net/xdp/xsk.c:1645
> notifier_call_chain+0xbc/0x410 kernel/notifier.c:85
> call_netdevice_notifiers_info+0xbe/0x140 net/core/dev.c:2230
> call_netdevice_notifiers_extack net/core/dev.c:2268 [inline]
> call_netdevice_notifiers net/core/dev.c:2282 [inline]
> unregister_netdevice_many_notify+0xf9d/0x2700 net/core/dev.c:12077
> unregister_netdevice_many net/core/dev.c:12140 [inline]
> unregister_netdevice_queue+0x305/0x3f0 net/core/dev.c:11984
> register_netdevice+0x18f1/0x2270 net/core/dev.c:11149
> lapbeth_new_device drivers/net/wan/lapbether.c:420 [inline]
> lapbeth_device_event+0x5b1/0xbe0 drivers/net/wan/lapbether.c:462
> notifier_call_chain+0xbc/0x410 kernel/notifier.c:85
> call_netdevice_notifiers_info+0xbe/0x140 net/core/dev.c:2230
> call_netdevice_notifiers_extack net/core/dev.c:2268 [inline]
> call_netdevice_notifiers net/core/dev.c:2282 [inline]
> __dev_notify_flags+0x12c/0x2e0 net/core/dev.c:9497
> netif_change_flags+0x108/0x160 net/core/dev.c:9526
> dev_change_flags+0xba/0x250 net/core/dev_api.c:68
> devinet_ioctl+0x11d5/0x1f50 net/ipv4/devinet.c:1200
> inet_ioctl+0x3a7/0x3f0 net/ipv4/af_inet.c:1001
> sock_do_ioctl+0x118/0x280 net/socket.c:1190
> sock_ioctl+0x227/0x6b0 net/socket.c:1311
> vfs_ioctl fs/ioctl.c:51 [inline]
> __do_sys_ioctl fs/ioctl.c:907 [inline]
> __se_sys_ioctl fs/ioctl.c:893 [inline]
> __x64_sys_ioctl+0x18e/0x210 fs/ioctl.c:893
> do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
> do_syscall_64+0xcd/0x4c0 arch/x86/entry/syscall_64.c:94
> entry_SYSCALL_64_after_hwframe+0x77/0x7f
>
> -> #1 (&dev_instance_lock_key#20){+.+.}-{4:4}:
> __mutex_lock_common kernel/locking/mutex.c:602 [inline]
> __mutex_lock+0x199/0xb90 kernel/locking/mutex.c:747
> netdev_lock include/linux/netdevice.h:2756 [inline]
> netdev_lock_ops include/net/netdev_lock.h:42 [inline]
> xsk_bind+0x37c/0x1570 net/xdp/xsk.c:1189
> __sys_bind_socket net/socket.c:1810 [inline]
> __sys_bind_socket net/socket.c:1802 [inline]
> __sys_bind+0x1a7/0x260 net/socket.c:1841
> __do_sys_bind net/socket.c:1846 [inline]
> __se_sys_bind net/socket.c:1844 [inline]
> __x64_sys_bind+0x72/0xb0 net/socket.c:1844
> do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
> do_syscall_64+0xcd/0x4c0 arch/x86/entry/syscall_64.c:94
> entry_SYSCALL_64_after_hwframe+0x77/0x7f
>
> -> #0 (&xs->mutex){+.+.}-{4:4}:
> check_prev_add kernel/locking/lockdep.c:3168 [inline]
> check_prevs_add kernel/locking/lockdep.c:3287 [inline]
> validate_chain kernel/locking/lockdep.c:3911 [inline]
> __lock_acquire+0x126f/0x1c90 kernel/locking/lockdep.c:5240
> lock_acquire kernel/locking/lockdep.c:5871 [inline]
> lock_acquire+0x179/0x350 kernel/locking/lockdep.c:5828
> __mutex_lock_common kernel/locking/mutex.c:602 [inline]
> __mutex_lock+0x199/0xb90 kernel/locking/mutex.c:747
> xsk_notifier+0x101/0x280 net/xdp/xsk.c:1649
> notifier_call_chain+0xbc/0x410 kernel/notifier.c:85
> call_netdevice_notifiers_info+0xbe/0x140 net/core/dev.c:2230
> call_netdevice_notifiers_extack net/core/dev.c:2268 [inline]
> call_netdevice_notifiers net/core/dev.c:2282 [inline]
> unregister_netdevice_many_notify+0xf9d/0x2700 net/core/dev.c:12077
> rtnl_delete_link net/core/rtnetlink.c:3511 [inline]
> rtnl_dellink+0x3cb/0xa80 net/core/rtnetlink.c:3553
> rtnetlink_rcv_msg+0x95e/0xe90 net/core/rtnetlink.c:6944
> netlink_rcv_skb+0x158/0x420 net/netlink/af_netlink.c:2534
> netlink_unicast_kernel net/netlink/af_netlink.c:1313 [inline]
> netlink_unicast+0x53d/0x7f0 net/netlink/af_netlink.c:1339
> netlink_sendmsg+0x8d1/0xdd0 net/netlink/af_netlink.c:1883
> sock_sendmsg_nosec net/socket.c:712 [inline]
> __sock_sendmsg net/socket.c:727 [inline]
> ____sys_sendmsg+0xa98/0xc70 net/socket.c:2566
> ___sys_sendmsg+0x134/0x1d0 net/socket.c:2620
> __sys_sendmsg+0x16d/0x220 net/socket.c:2652
> do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
> do_syscall_64+0xcd/0x4c0 arch/x86/entry/syscall_64.c:94
> entry_SYSCALL_64_after_hwframe+0x77/0x7f
>
> other info that might help us debug this:
>
> Chain exists of:
> &xs->mutex --> &dev_instance_lock_key#20 --> &net->xdp.lock
>
> Possible unsafe locking scenario:
>
> CPU0 CPU1
> ---- ----
> lock(&net->xdp.lock);
> lock(&dev_instance_lock_key#20);
> lock(&net->xdp.lock);
> lock(&xs->mutex);
I feel the above race map is not that right?
My understanding is as shown below.
CPU 0 CPU 1
--- ---
unregister_netdevice_many_notify()
xsk_bind()
netdev_lock_ops(dev);
mutex_lock(&xs->mutex);
netdev_lock_ops(dev);
xsk_notifier()
mutex_lock(&net->xdp.lock);
mutex_lock(&xs->mutex);
So ABBA lock case happens, IIUC.
Thanks,
Jason
>
> *** DEADLOCK ***
>
> 2 locks held by syz.1.1331/11144:
> #0: ffffffff9034e4a8 (rtnl_mutex){+.+.}-{4:4}, at: rtnl_lock net/core/rtnetlink.c:80 [inline]
> #0: ffffffff9034e4a8 (rtnl_mutex){+.+.}-{4:4}, at: rtnl_net_lock include/linux/rtnetlink.h:130 [inline]
> #0: ffffffff9034e4a8 (rtnl_mutex){+.+.}-{4:4}, at: rtnl_dellink+0x277/0xa80 net/core/rtnetlink.c:3545
> #1: ffff888052f43d58 (&net->xdp.lock){+.+.}-{4:4}, at: xsk_notifier+0xa4/0x280 net/xdp/xsk.c:1645
>
> stack backtrace:
> CPU: 1 UID: 0 PID: 11144 Comm: syz.1.1331 Not tainted 6.16.0-rc3-syzkaller-00042-g78f4e737a53e #0 PREEMPT(full)
> Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/07/2025
> Call Trace:
> <TASK>
> __dump_stack lib/dump_stack.c:94 [inline]
> dump_stack_lvl+0x116/0x1f0 lib/dump_stack.c:120
> print_circular_bug+0x275/0x350 kernel/locking/lockdep.c:2046
> check_noncircular+0x14c/0x170 kernel/locking/lockdep.c:2178
> check_prev_add kernel/locking/lockdep.c:3168 [inline]
> check_prevs_add kernel/locking/lockdep.c:3287 [inline]
> validate_chain kernel/locking/lockdep.c:3911 [inline]
> __lock_acquire+0x126f/0x1c90 kernel/locking/lockdep.c:5240
> lock_acquire kernel/locking/lockdep.c:5871 [inline]
> lock_acquire+0x179/0x350 kernel/locking/lockdep.c:5828
> __mutex_lock_common kernel/locking/mutex.c:602 [inline]
> __mutex_lock+0x199/0xb90 kernel/locking/mutex.c:747
> xsk_notifier+0x101/0x280 net/xdp/xsk.c:1649
> notifier_call_chain+0xbc/0x410 kernel/notifier.c:85
> call_netdevice_notifiers_info+0xbe/0x140 net/core/dev.c:2230
> call_netdevice_notifiers_extack net/core/dev.c:2268 [inline]
> call_netdevice_notifiers net/core/dev.c:2282 [inline]
> unregister_netdevice_many_notify+0xf9d/0x2700 net/core/dev.c:12077
> rtnl_delete_link net/core/rtnetlink.c:3511 [inline]
> rtnl_dellink+0x3cb/0xa80 net/core/rtnetlink.c:3553
> rtnetlink_rcv_msg+0x95e/0xe90 net/core/rtnetlink.c:6944
> netlink_rcv_skb+0x158/0x420 net/netlink/af_netlink.c:2534
> netlink_unicast_kernel net/netlink/af_netlink.c:1313 [inline]
> netlink_unicast+0x53d/0x7f0 net/netlink/af_netlink.c:1339
> netlink_sendmsg+0x8d1/0xdd0 net/netlink/af_netlink.c:1883
> sock_sendmsg_nosec net/socket.c:712 [inline]
> __sock_sendmsg net/socket.c:727 [inline]
> ____sys_sendmsg+0xa98/0xc70 net/socket.c:2566
> ___sys_sendmsg+0x134/0x1d0 net/socket.c:2620
> __sys_sendmsg+0x16d/0x220 net/socket.c:2652
> do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
> do_syscall_64+0xcd/0x4c0 arch/x86/entry/syscall_64.c:94
> entry_SYSCALL_64_after_hwframe+0x77/0x7f
> RIP: 0033:0x7f97c7b8e929
> 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:00007f97c8abc038 EFLAGS: 00000246 ORIG_RAX: 000000000000002e
> RAX: ffffffffffffffda RBX: 00007f97c7db5fa0 RCX: 00007f97c7b8e929
> RDX: 0000000000000000 RSI: 0000200000000040 RDI: 0000000000000003
> RBP: 00007f97c7c10b39 R08: 0000000000000000 R09: 0000000000000000
> R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
> R13: 0000000000000000 R14: 00007f97c7db5fa0 R15: 00007fff09d1ae48
> </TASK>
> batman_adv: batadv0: Removing interface: batadv_slave_1
>
>
> ---
> 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
>
Powered by blists - more mailing lists