[v6.1] INFO: task hung in genl_rcv_msg (3)

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: 7b34dc04e4ff Linux 6.1.154
git tree: linux-6.1.y
console output: https://syzkaller.appspot.com/x/log.txt?x=167302e2580000
kernel config: https://syzkaller.appspot.com/x/.config?x=68aa5a3af1cb953a
dashboard link: https://syzkaller.appspot.com/bug?extid=5f67c2c2485c3e2149ba
compiler: Debian clang version 20.1.8 (++20250708063551+0c9f909b7976-1~exp1~20250708183702.136), Debian LLD 20.1.8
userspace arch: arm64

Unfortunately, I don't have any reproducer for this issue yet.

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/e71c87e0f2ec/disk-7b34dc04.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/6b873083d403/vmlinux-7b34dc04.xz
kernel image: https://storage.googleapis.com/syzbot-assets/83659dda663d/Image-7b34dc04.gz.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+5f67c2...@syzkaller.appspotmail.com

INFO: task syz.4.250:5535 blocked for more than 143 seconds.
Not tainted syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:syz.4.250 state:D stack:0 pid:5535 ppid:4320 flags:0x00000001
Call trace:
__switch_to+0x2f4/0x568 arch/arm64/kernel/process.c:555
context_switch kernel/sched/core.c:5244 [inline]
__schedule+0xddc/0x1b18 kernel/sched/core.c:6561
schedule+0xc4/0x170 kernel/sched/core.c:6637
schedule_preempt_disabled+0x18/0x2c kernel/sched/core.c:6696
__mutex_lock_common+0xad4/0x1f38 kernel/locking/mutex.c:679
__mutex_lock kernel/locking/mutex.c:747 [inline]
mutex_lock_nested+0x38/0x44 kernel/locking/mutex.c:799
genl_lock net/netlink/genetlink.c:33 [inline]
genl_rcv_msg+0xec/0x62c net/netlink/genetlink.c:848
netlink_rcv_skb+0x208/0x3c4 net/netlink/af_netlink.c:2511
genl_rcv+0x38/0x50 net/netlink/genetlink.c:861
netlink_unicast_kernel net/netlink/af_netlink.c:1318 [inline]
netlink_unicast+0x60c/0x824 net/netlink/af_netlink.c:1344
netlink_sendmsg+0x6e8/0x9b0 net/netlink/af_netlink.c:1872
sock_sendmsg_nosec net/socket.c:718 [inline]
__sock_sendmsg net/socket.c:730 [inline]
__sys_sendto+0x304/0x3fc net/socket.c:2153
__do_sys_sendto net/socket.c:2165 [inline]
__se_sys_sendto net/socket.c:2161 [inline]
__arm64_sys_sendto+0xd8/0xf8 net/socket.c:2161
__invoke_syscall arch/arm64/kernel/syscall.c:38 [inline]
invoke_syscall+0x98/0x2bc arch/arm64/kernel/syscall.c:52
el0_svc_common+0x138/0x258 arch/arm64/kernel/syscall.c:140
do_el0_svc+0x58/0x13c arch/arm64/kernel/syscall.c:204
el0_svc+0x58/0x138 arch/arm64/kernel/entry-common.c:637
el0t_64_sync_handler+0x84/0xf0 arch/arm64/kernel/entry-common.c:655
el0t_64_sync+0x18c/0x190 arch/arm64/kernel/entry.S:585

Showing all locks held in the system:
1 lock held by rcu_tasks_kthre/12:
#0: ffff800015297770 (rcu_tasks.tasks_gp_mutex){+.+.}-{3:3}, at: rcu_tasks_one_gp+0x40/0xbb4 kernel/rcu/tasks.h:517
1 lock held by rcu_tasks_trace/13:
#0: ffff800015297f90 (rcu_tasks_trace.tasks_gp_mutex){+.+.}-{3:3}, at: rcu_tasks_one_gp+0x40/0xbb4 kernel/rcu/tasks.h:517
1 lock held by khungtaskd/28:
#0: ffff800015296e00 (rcu_read_lock){....}-{1:2}, at: rcu_lock_acquire+0xc/0x44 include/linux/rcupdate.h:349
2 locks held by getty/4080:
#0: ffff0000d6d7e098 (&tty->ldisc_sem){++++}-{0:0}, at: ldsem_down_read+0x3c/0x4c drivers/tty/tty_ldsem.c:340
#1: ffff80001ceb62f0 (&ldata->atomic_read_lock){+.+.}-{3:3}, at: n_tty_read+0x2ec/0xf9c drivers/tty/n_tty.c:2198
3 locks held by syz-executor/4329:
#0: ffff0000d4b510b8 (&hdev->req_lock){+.+.}-{3:3}, at: hci_dev_do_close net/bluetooth/hci_core.c:508 [inline]
#0: ffff0000d4b510b8 (&hdev->req_lock){+.+.}-{3:3}, at: hci_unregister_dev+0x1f0/0x4b4 net/bluetooth/hci_core.c:2705
#1: ffff0000d4b50078 (&hdev->lock){+.+.}-{3:3}, at: hci_dev_close_sync+0x398/0xf18 net/bluetooth/hci_sync.c:5219
#2: ffff800017886768 (hci_cb_list_lock){+.+.}-{3:3}, at: hci_disconn_cfm include/net/bluetooth/hci_core.h:1799 [inline]
#2: ffff800017886768 (hci_cb_list_lock){+.+.}-{3:3}, at: hci_conn_hash_flush+0xb0/0x270 net/bluetooth/hci_conn.c:2504
2 locks held by kworker/0:7/5097:
#0: ffff0000c0020938 ((wq_completion)events){+.+.}-{0:0}, at: process_one_work+0x6b4/0x13a8 kernel/workqueue.c:2265
#1: ffff8000207a7c20 (free_ipc_work){+.+.}-{0:0}, at: process_one_work+0x6f8/0x13a8 kernel/workqueue.c:2267
2 locks held by syz.2.238/5506:
2 locks held by syz.4.250/5535:
#0: ffff80001778d9b0 (cb_lock){++++}-{3:3}, at: genl_rcv+0x28/0x50 net/netlink/genetlink.c:860
#1: ffff80001778d7c8 (genl_mutex){+.+.}-{3:3}, at: genl_lock net/netlink/genetlink.c:33 [inline]
#1: ffff80001778d7c8 (genl_mutex){+.+.}-{3:3}, at: genl_rcv_msg+0xec/0x62c net/netlink/genetlink.c:848
2 locks held by syz.0.256/5559:
#0: ffff80001778d9b0 (cb_lock){++++}-{3:3}, at: genl_rcv+0x28/0x50 net/netlink/genetlink.c:860
#1: ffff80001778d7c8 (genl_mutex){+.+.}-{3:3}, at: genl_lock net/netlink/genetlink.c:33 [inline]
#1: ffff80001778d7c8 (genl_mutex){+.+.}-{3:3}, at: genl_rcv_msg+0xec/0x62c net/netlink/genetlink.c:848
2 locks held by syz-executor/5634:
#0: ffff80001778d9b0 (cb_lock){++++}-{3:3}, at: genl_rcv+0x28/0x50 net/netlink/genetlink.c:860
#1: ffff80001778d7c8 (genl_mutex){+.+.}-{3:3}, at: genl_lock net/netlink/genetlink.c:33 [inline]
#1: ffff80001778d7c8 (genl_mutex){+.+.}-{3:3}, at: genl_rcv_msg+0xec/0x62c net/netlink/genetlink.c:848
2 locks held by syz.1.271/5652:
#0: ffff80001778d9b0 (cb_lock){++++}-{3:3}, at: genl_rcv+0x28/0x50 net/netlink/genetlink.c:860
#1: ffff80001778d7c8 (genl_mutex){+.+.}-{3:3}, at: genl_lock net/netlink/genetlink.c:33 [inline]
#1: ffff80001778d7c8 (genl_mutex){+.+.}-{3:3}, at: genl_rcv_msg+0xec/0x62c net/netlink/genetlink.c:848
2 locks held by syz-executor/5665:
#0: ffff80001778d9b0 (cb_lock){++++}-{3:3}, at: genl_rcv+0x28/0x50 net/netlink/genetlink.c:860
#1: ffff80001778d7c8 (genl_mutex){+.+.}-{3:3}, at: genl_lock net/netlink/genetlink.c:33 [inline]
#1: ffff80001778d7c8 (genl_mutex){+.+.}-{3:3}, at: genl_rcv_msg+0xec/0x62c net/netlink/genetlink.c:848
2 locks held by syz-executor/5699:
#0: ffff80001778d9b0 (cb_lock){++++}-{3:3}, at: genl_rcv+0x28/0x50 net/netlink/genetlink.c:860
#1: ffff80001778d7c8 (genl_mutex){+.+.}-{3:3}, at: genl_lock net/netlink/genetlink.c:33 [inline]
#1: ffff80001778d7c8 (genl_mutex){+.+.}-{3:3}, at: genl_rcv_msg+0xec/0x62c net/netlink/genetlink.c:848
2 locks held by syz-executor/5713:
#0: ffff80001778d9b0 (cb_lock){++++}-{3:3}, at: genl_rcv+0x28/0x50 net/netlink/genetlink.c:860
#1: ffff80001778d7c8 (genl_mutex){+.+.}-{3:3}, at: genl_lock net/netlink/genetlink.c:33 [inline]
#1: ffff80001778d7c8 (genl_mutex){+.+.}-{3:3}, at: genl_rcv_msg+0xec/0x62c net/netlink/genetlink.c:848
2 locks held by syz-executor/5736:
#0: ffff80001778d9b0 (cb_lock){++++}-{3:3}, at: genl_rcv+0x28/0x50 net/netlink/genetlink.c:860
#1: ffff80001778d7c8 (genl_mutex){+.+.}-{3:3}, at: genl_lock net/netlink/genetlink.c:33 [inline]
#1: ffff80001778d7c8 (genl_mutex){+.+.}-{3:3}, at: genl_rcv_msg+0xec/0x62c net/netlink/genetlink.c:848
2 locks held by syz-executor/5749:
#0: ffff80001778d9b0 (cb_lock){++++}-{3:3}, at: genl_rcv+0x28/0x50 net/netlink/genetlink.c:860
#1: ffff80001778d7c8 (genl_mutex){+.+.}-{3:3}, at: genl_lock net/netlink/genetlink.c:33 [inline]
#1: ffff80001778d7c8 (genl_mutex){+.+.}-{3:3}, at: genl_rcv_msg+0xec/0x62c net/netlink/genetlink.c:848
2 locks held by syz-executor/5761:
#0: ffff80001778d9b0 (cb_lock){++++}-{3:3}, at: genl_rcv+0x28/0x50 net/netlink/genetlink.c:860
#1: ffff80001778d7c8 (genl_mutex){+.+.}-{3:3}, at: genl_lock net/netlink/genetlink.c:33 [inline]
#1: ffff80001778d7c8 (genl_mutex){+.+.}-{3:3}, at: genl_rcv_msg+0xec/0x62c net/netlink/genetlink.c:848
2 locks held by syz-executor/5773:
#0: ffff80001778d9b0 (cb_lock){++++}-{3:3}, at: genl_rcv+0x28/0x50 net/netlink/genetlink.c:860
#1: ffff80001778d7c8 (genl_mutex){+.+.}-{3:3}, at: genl_lock net/netlink/genetlink.c:33 [inline]
#1: ffff80001778d7c8 (genl_mutex){+.+.}-{3:3}, at: genl_rcv_msg+0xec/0x62c net/netlink/genetlink.c:848
2 locks held by syz-executor/5792:
#0: ffff80001778d9b0 (cb_lock){++++}-{3:3}, at: genl_rcv+0x28/0x50 net/netlink/genetlink.c:860
#1: ffff80001778d7c8 (genl_mutex){+.+.}-{3:3}, at: genl_lock net/netlink/genetlink.c:33 [inline]
#1: ffff80001778d7c8 (genl_mutex){+.+.}-{3:3}, at: genl_rcv_msg+0xec/0x62c net/netlink/genetlink.c:848
2 locks held by syz-executor/5805:
#0: ffff80001778d9b0 (cb_lock){++++}-{3:3}, at: genl_rcv+0x28/0x50 net/netlink/genetlink.c:860
#1: ffff80001778d7c8 (genl_mutex){+.+.}-{3:3}, at: genl_lock net/netlink/genetlink.c:33 [inline]
#1: ffff80001778d7c8 (genl_mutex){+.+.}-{3:3}, at: genl_rcv_msg+0xec/0x62c net/netlink/genetlink.c:848
2 locks held by syz-executor/5817:
#0: ffff80001778d9b0 (cb_lock){++++}-{3:3}, at: genl_rcv+0x28/0x50 net/netlink/genetlink.c:860
#1: ffff80001778d7c8 (genl_mutex){+.+.}-{3:3}, at: genl_lock net/netlink/genetlink.c:33 [inline]
#1: ffff80001778d7c8 (genl_mutex){+.+.}-{3:3}, at: genl_rcv_msg+0xec/0x62c net/netlink/genetlink.c:848

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