Re: [syzbot] [net?] INFO: task hung in genl_rcv_msg (4)

syzbot
2024-10-25T02:51:29Z

syzbot has found a reproducer for the following issue on:

HEAD commit: c2ee9f594da8 KVM: selftests: Fix build on on non-x86 archi..
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=13815e40580000
kernel config: https://syzkaller.appspot.com/x/.config?x=fd919c0fc1af4272
dashboard link: https://syzkaller.appspot.com/bug?extid=85d0bec020d805014a3a
compiler: Debian clang version 15.0.6, GNU ld (GNU Binutils for Debian) 2.40
syz repro: https://syzkaller.appspot.com/x/repro.syz?x=12d40230580000
C reproducer: https://syzkaller.appspot.com/x/repro.c?x=16d40230580000

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/4784686ffc6b/disk-c2ee9f59.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/fbec5f2b06d9/vmlinux-c2ee9f59.xz
kernel image: https://storage.googleapis.com/syzbot-assets/6d8289609976/bzImage-c2ee9f59.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+85d0bec020d805014a3a@syzkaller.appspotmail.com

INFO: task syz-executor279:5856 blocked for more than 160 seconds.
Not tainted 6.12.0-rc4-syzkaller-00047-gc2ee9f594da8 #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:syz-executor279 state:D stack:20448 pid:5856 tgid:5856 ppid:5854 flags:0x00000002
Call Trace:
<TASK>
context_switch kernel/sched/core.c:5328 [inline]
__schedule+0x185a/0x4b70 kernel/sched/core.c:6690
__schedule_loop kernel/sched/core.c:6767 [inline]
schedule+0x14b/0x320 kernel/sched/core.c:6782
schedule_preempt_disabled+0x13/0x30 kernel/sched/core.c:6839
__mutex_lock_common kernel/locking/mutex.c:684 [inline]
__mutex_lock+0x6a7/0xd70 kernel/locking/mutex.c:752
genl_lock net/netlink/genetlink.c:35 [inline]
genl_op_lock net/netlink/genetlink.c:60 [inline]
genl_rcv_msg+0x121/0xec0 net/netlink/genetlink.c:1209
netlink_rcv_skb+0x1e3/0x430 net/netlink/af_netlink.c:2551
genl_rcv+0x28/0x40 net/netlink/genetlink.c:1219
netlink_unicast_kernel net/netlink/af_netlink.c:1331 [inline]
netlink_unicast+0x7f6/0x990 net/netlink/af_netlink.c:1357
netlink_sendmsg+0x8e4/0xcb0 net/netlink/af_netlink.c:1901
sock_sendmsg_nosec net/socket.c:729 [inline]
__sock_sendmsg+0x221/0x270 net/socket.c:744
__sys_sendto+0x39b/0x4f0 net/socket.c:2214
__do_sys_sendto net/socket.c:2226 [inline]
__se_sys_sendto net/socket.c:2222 [inline]
__x64_sys_sendto+0xde/0x100 net/socket.c:2222
do_syscall_x64 arch/x86/entry/common.c:52 [inline]
do_syscall_64+0xf3/0x230 arch/x86/entry/common.c:83
entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7fbf1b8e2273
RSP: 002b:00007ffcd832d5e8 EFLAGS: 00000202 ORIG_RAX: 000000000000002c
RAX: ffffffffffffffda RBX: 00007fbf1b96b300 RCX: 00007fbf1b8e2273
RDX: 0000000000000024 RSI: 00007fbf1b96b350 RDI: 0000000000000003
RBP: 0000000000000003 R08: 00007ffcd832d604 R09: 000000000000000c
R10: 0000000000000000 R11: 0000000000000202 R12: 0000000000000001
R13: 0000000000000000 R14: 00007fbf1b96b350 R15: 0000000000000000
</TASK>

Showing all locks held in the system:
3 locks held by kworker/u8:1/12:
#0: ffff88801ac89148 ((wq_completion)events_unbound){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:3204 [inline]
#0: ffff88801ac89148 ((wq_completion)events_unbound){+.+.}-{0:0}, at: process_scheduled_works+0x93b/0x1850 kernel/workqueue.c:3310
#1: ffffc90000117d00 ((linkwatch_work).work){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:3205 [inline]
#1: ffffc90000117d00 ((linkwatch_work).work){+.+.}-{0:0}, at: process_scheduled_works+0x976/0x1850 kernel/workqueue.c:3310
#2: ffffffff8fcc0948 (rtnl_mutex){+.+.}-{3:3}, at: linkwatch_event+0xe/0x60 net/core/link_watch.c:276
1 lock held by khungtaskd/30:
#0: ffffffff8e937e20 (rcu_read_lock){....}-{1:2}, at: rcu_lock_acquire include/linux/rcupdate.h:337 [inline]
#0: ffffffff8e937e20 (rcu_read_lock){....}-{1:2}, at: rcu_read_lock include/linux/rcupdate.h:849 [inline]
#0: ffffffff8e937e20 (rcu_read_lock){....}-{1:2}, at: debug_show_all_locks+0x55/0x2a0 kernel/locking/lockdep.c:6720
7 locks held by kworker/u8:3/52:
3 locks held by kworker/u8:6/2129:
#0: ffff88814cfae948 ((wq_completion)ipv6_addrconf){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:3204 [inline]
#0: ffff88814cfae948 ((wq_completion)ipv6_addrconf){+.+.}-{0:0}, at: process_scheduled_works+0x93b/0x1850 kernel/workqueue.c:3310
#1: ffffc90004e1fd00 ((work_completion)(&(&ifa->dad_work)->work)){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:3205 [inline]
#1: ffffc90004e1fd00 ((work_completion)(&(&ifa->dad_work)->work)){+.+.}-{0:0}, at: process_scheduled_works+0x976/0x1850 kernel/workqueue.c:3310
#2: ffffffff8fcc0948 (rtnl_mutex){+.+.}-{3:3}, at: addrconf_dad_work+0xd0/0x16f0 net/ipv6/addrconf.c:4196
3 locks held by kworker/1:2/2145:
#0: ffff88801ac81948 ((wq_completion)events_power_efficient){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:3204 [inline]
#0: ffff88801ac81948 ((wq_completion)events_power_efficient){+.+.}-{0:0}, at: process_scheduled_works+0x93b/0x1850 kernel/workqueue.c:3310
#1: ffffc90004f4fd00 ((reg_check_chans).work){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:3205 [inline]
#1: ffffc90004f4fd00 ((reg_check_chans).work){+.+.}-{0:0}, at: process_scheduled_works+0x976/0x1850 kernel/workqueue.c:3310
#2: ffffffff8fcc0948 (rtnl_mutex){+.+.}-{3:3}, at: reg_check_chans_work+0x99/0xfd0 net/wireless/reg.c:2480
2 locks held by klogd/5191:
2 locks held by dhcpcd/5496:
2 locks held by getty/5586:
#0: ffff8880354520a0 (&tty->ldisc_sem){++++}-{0:0}, at: tty_ldisc_ref_wait+0x25/0x70 drivers/tty/tty_ldisc.c:243
#1: ffffc90002f062f0 (&ldata->atomic_read_lock){+.+.}-{3:3}, at: n_tty_read+0x6a6/0x1e00 drivers/tty/n_tty.c:2211
1 lock held by dhcpcd/5644:
2 locks held by syz-executor279/5856:
#0: ffffffff8fd266b0 (cb_lock){++++}-{3:3}, at: genl_rcv+0x19/0x40 net/netlink/genetlink.c:1218
#1: ffffffff8fd26568 (genl_mutex){+.+.}-{3:3}, at: genl_lock net/netlink/genetlink.c:35 [inline]
#1: ffffffff8fd26568 (genl_mutex){+.+.}-{3:3}, at: genl_op_lock net/netlink/genetlink.c:60 [inline]
#1: ffffffff8fd26568 (genl_mutex){+.+.}-{3:3}, at: genl_rcv_msg+0x121/0xec0 net/netlink/genetlink.c:1209
6 locks held by syz-executor279/5858:
1 lock held by syz-executor279/5859:
#0: ffffffff8fcc0948 (rtnl_mutex){+.+.}-{3:3}, at: rtnl_lock net/core/rtnetlink.c:79 [inline]
#0: ffffffff8fcc0948 (rtnl_mutex){+.+.}-{3:3}, at: rtnetlink_rcv_msg+0x6e6/0xcf0 net/core/rtnetlink.c:6672
6 locks held by syz-executor279/5860:
#0: ffff8880746c6420 (sb_writers#9){.+.+}-{0:0}, at: file_start_write include/linux/fs.h:2931 [inline]
#0: ffff8880746c6420 (sb_writers#9){.+.+}-{0:0}, at: vfs_write+0x224/0xc90 fs/read_write.c:679

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