On 08/04, syzbot wrote: > Hello, > > syzbot found the following issue on: > > HEAD commit: d2eedaa3909b Merge tag 'rtc-6.17' of git://git.kernel.org/.. > git tree: upstream > console output: https://syzkaller.appspot.com/x/log.txt?x=159482f0580000 > kernel config: https://syzkaller.appspot.com/x/.config?x=75e522434dc68cb9 > dashboard link: https://syzkaller.appspot.com/bug?extid=e6300f66a999a6612477 > compiler: Debian clang version 20.1.7 (++20250616065708+6146a88f6049-1~exp1~20250616065826.132), Debian LLD 20.1.7 > > Unfortunately, I don't have any reproducer for this issue yet. > > Downloadable assets: > disk image: https://storage.googleapis.com/syzbot-assets/3435b26b899d/disk-d2eedaa3.raw.xz > vmlinux: https://storage.googleapis.com/syzbot-assets/531223373575/vmlinux-d2eedaa3.xz > kernel image: https://storage.googleapis.com/syzbot-assets/e82f9030b8d5/bzImage-d2eedaa3.xz > > IMPORTANT: if you fix the issue, please add the following tag to the commit: > Reported-by: syzbot+e6300f66a999a6612477@xxxxxxxxxxxxxxxxxxxxxxxxx > > ====================================================== > WARNING: possible circular locking dependency detected > 6.16.0-syzkaller-11489-gd2eedaa3909b #0 Not tainted > ------------------------------------------------------ > syz.8.4735/22857 is trying to acquire lock: > ffff8880223e06b8 (&xs->mutex){+.+.}-{4:4}, at: xsk_diag_fill net/xdp/xsk_diag.c:113 [inline] > ffff8880223e06b8 (&xs->mutex){+.+.}-{4:4}, at: xsk_diag_dump+0x550/0x14d0 net/xdp/xsk_diag.c:166 > > but task is already holding lock: > ffff888031291c98 (&net->xdp.lock){+.+.}-{4:4}, at: xsk_diag_dump+0x178/0x14d0 net/xdp/xsk_diag.c:158 > > which lock already depends on the new lock. > > > the existing dependency chain (in reverse order) is: > > -> #2 (&net->xdp.lock){+.+.}-{4:4}: > lock_acquire+0x120/0x360 kernel/locking/lockdep.c:5868 > __mutex_lock_common kernel/locking/mutex.c:598 [inline] > __mutex_lock+0x187/0x1360 kernel/locking/mutex.c:760 > xsk_notifier+0x89/0x230 net/xdp/xsk.c:1664 > notifier_call_chain+0x1b6/0x3e0 kernel/notifier.c:85 > call_netdevice_notifiers_extack net/core/dev.c:2267 [inline] > call_netdevice_notifiers net/core/dev.c:2281 [inline] > unregister_netdevice_many_notify+0x14d7/0x1ff0 net/core/dev.c:12156 > unregister_netdevice_many net/core/dev.c:12219 [inline] > unregister_netdevice_queue+0x33c/0x380 net/core/dev.c:12063 > register_netdevice+0x1689/0x1ae0 net/core/dev.c:11241 > bpq_new_device drivers/net/hamradio/bpqether.c:481 [inline] > bpq_device_event+0x491/0x600 drivers/net/hamradio/bpqether.c:523 > notifier_call_chain+0x1b6/0x3e0 kernel/notifier.c:85 > call_netdevice_notifiers_extack net/core/dev.c:2267 [inline] > call_netdevice_notifiers net/core/dev.c:2281 [inline] > __dev_notify_flags+0x18d/0x2e0 net/core/dev.c:-1 > netif_change_flags+0xe8/0x1a0 net/core/dev.c:9608 > dev_change_flags+0x130/0x260 net/core/dev_api.c:68 > devinet_ioctl+0xbb4/0x1b50 net/ipv4/devinet.c:1200 > inet_ioctl+0x3c0/0x4c0 net/ipv4/af_inet.c:1001 > sock_do_ioctl+0xdc/0x300 net/socket.c:1238 > sock_ioctl+0x576/0x790 net/socket.c:1359 > vfs_ioctl fs/ioctl.c:51 [inline] > __do_sys_ioctl fs/ioctl.c:598 [inline] > __se_sys_ioctl+0xfc/0x170 fs/ioctl.c:584 > do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] > do_syscall_64+0xfa/0x3b0 arch/x86/entry/syscall_64.c:94 > entry_SYSCALL_64_after_hwframe+0x77/0x7f > > -> #1 (&dev_instance_lock_key#20){+.+.}-{4:4}: > lock_acquire+0x120/0x360 kernel/locking/lockdep.c:5868 > __mutex_lock_common kernel/locking/mutex.c:598 [inline] > __mutex_lock+0x187/0x1360 kernel/locking/mutex.c:760 > netdev_lock include/linux/netdevice.h:2758 [inline] > netdev_lock_ops include/net/netdev_lock.h:42 [inline] > xsk_bind+0x2f7/0xf90 net/xdp/xsk.c:1193 > __sys_bind_socket net/socket.c:1858 [inline] > __sys_bind+0x2c6/0x3e0 net/socket.c:1889 > __do_sys_bind net/socket.c:1894 [inline] > __se_sys_bind net/socket.c:1892 [inline] > __x64_sys_bind+0x7a/0x90 net/socket.c:1892 > do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] > do_syscall_64+0xfa/0x3b0 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:3165 [inline] > check_prevs_add kernel/locking/lockdep.c:3284 [inline] > validate_chain+0xb9b/0x2140 kernel/locking/lockdep.c:3908 > __lock_acquire+0xab9/0xd20 kernel/locking/lockdep.c:5237 > lock_acquire+0x120/0x360 kernel/locking/lockdep.c:5868 > __mutex_lock_common kernel/locking/mutex.c:598 [inline] > __mutex_lock+0x187/0x1360 kernel/locking/mutex.c:760 > xsk_diag_fill net/xdp/xsk_diag.c:113 [inline] > xsk_diag_dump+0x550/0x14d0 net/xdp/xsk_diag.c:166 > netlink_dump+0x6e4/0xe90 net/netlink/af_netlink.c:2327 > __netlink_dump_start+0x5cb/0x7e0 net/netlink/af_netlink.c:2442 > netlink_dump_start include/linux/netlink.h:341 [inline] > xsk_diag_handler_dump+0x183/0x220 net/xdp/xsk_diag.c:193 > sock_diag_rcv_msg+0x4cc/0x600 net/core/sock_diag.c:-1 > netlink_rcv_skb+0x208/0x470 net/netlink/af_netlink.c:2552 > netlink_unicast_kernel net/netlink/af_netlink.c:1320 [inline] > netlink_unicast+0x82f/0x9e0 net/netlink/af_netlink.c:1346 > netlink_sendmsg+0x805/0xb30 net/netlink/af_netlink.c:1896 > sock_sendmsg_nosec net/socket.c:714 [inline] > __sock_sendmsg+0x21c/0x270 net/socket.c:729 > sock_write_iter+0x258/0x330 net/socket.c:1179 > do_iter_readv_writev+0x56e/0x7f0 fs/read_write.c:-1 > vfs_writev+0x31a/0x960 fs/read_write.c:1057 > do_writev+0x14d/0x2d0 fs/read_write.c:1103 > do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] > do_syscall_64+0xfa/0x3b0 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); > > *** DEADLOCK *** > > 2 locks held by syz.8.4735/22857: > #0: ffff8880223e16d0 (nlk_cb_mutex-SOCK_DIAG){+.+.}-{4:4}, at: __netlink_dump_start+0xfe/0x7e0 net/netlink/af_netlink.c:2406 > #1: ffff888031291c98 (&net->xdp.lock){+.+.}-{4:4}, at: xsk_diag_dump+0x178/0x14d0 net/xdp/xsk_diag.c:158 > > stack backtrace: > CPU: 0 UID: 0 PID: 22857 Comm: syz.8.4735 Not tainted 6.16.0-syzkaller-11489-gd2eedaa3909b #0 PREEMPT(full) > Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/12/2025 > Call Trace: > <TASK> > dump_stack_lvl+0x189/0x250 lib/dump_stack.c:120 > print_circular_bug+0x2ee/0x310 kernel/locking/lockdep.c:2043 > check_noncircular+0x134/0x160 kernel/locking/lockdep.c:2175 > check_prev_add kernel/locking/lockdep.c:3165 [inline] > check_prevs_add kernel/locking/lockdep.c:3284 [inline] > validate_chain+0xb9b/0x2140 kernel/locking/lockdep.c:3908 > __lock_acquire+0xab9/0xd20 kernel/locking/lockdep.c:5237 > lock_acquire+0x120/0x360 kernel/locking/lockdep.c:5868 > __mutex_lock_common kernel/locking/mutex.c:598 [inline] > __mutex_lock+0x187/0x1360 kernel/locking/mutex.c:760 > xsk_diag_fill net/xdp/xsk_diag.c:113 [inline] > xsk_diag_dump+0x550/0x14d0 net/xdp/xsk_diag.c:166 > netlink_dump+0x6e4/0xe90 net/netlink/af_netlink.c:2327 > __netlink_dump_start+0x5cb/0x7e0 net/netlink/af_netlink.c:2442 > netlink_dump_start include/linux/netlink.h:341 [inline] > xsk_diag_handler_dump+0x183/0x220 net/xdp/xsk_diag.c:193 > sock_diag_rcv_msg+0x4cc/0x600 net/core/sock_diag.c:-1 > netlink_rcv_skb+0x208/0x470 net/netlink/af_netlink.c:2552 > netlink_unicast_kernel net/netlink/af_netlink.c:1320 [inline] > netlink_unicast+0x82f/0x9e0 net/netlink/af_netlink.c:1346 > netlink_sendmsg+0x805/0xb30 net/netlink/af_netlink.c:1896 > sock_sendmsg_nosec net/socket.c:714 [inline] > __sock_sendmsg+0x21c/0x270 net/socket.c:729 > sock_write_iter+0x258/0x330 net/socket.c:1179 > do_iter_readv_writev+0x56e/0x7f0 fs/read_write.c:-1 > vfs_writev+0x31a/0x960 fs/read_write.c:1057 > do_writev+0x14d/0x2d0 fs/read_write.c:1103 > do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] > do_syscall_64+0xfa/0x3b0 arch/x86/entry/syscall_64.c:94 > entry_SYSCALL_64_after_hwframe+0x77/0x7f > RIP: 0033:0x7f6e7b38eb69 > 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:00007f6e791d5038 EFLAGS: 00000246 ORIG_RAX: 0000000000000014 > RAX: ffffffffffffffda RBX: 00007f6e7b5b6160 RCX: 00007f6e7b38eb69 > RDX: 0000000000000001 RSI: 0000200000000140 RDI: 0000000000000007 > RBP: 00007f6e7b411df1 R08: 0000000000000000 R09: 0000000000000000 > R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000 > R13: 0000000000000000 R14: 00007f6e7b5b6160 R15: 00007ffdbe0ab9a8 > </TASK> Looks similar to [0] but this time comes via bpq_device_event. I can try to pack the fix from 0 and do something similar here as well.. 0: https://lore.kernel.org/netdev/685af3b1.a00a0220.2e5631.0091.GAE@xxxxxxxxxx/
