syzbot


INFO: task hung in bpf_exit_net

Status: fixed on 2018/02/04 11:35
Subsystems: net
[Documentation on labels]
Reported-by: syzbot+21b498fc12cf2041655f8e1eeae0733807d794b3@syzkaller.appspotmail.com
Fix commit: b6c5734db070 sctp: fix the handling of ICMP Frag Needed for too small MTUs
First crash: 2327d, last: 2327d

Sample crash report:
sctp: sctp_transport_update_pmtu: Reported pmtu 508 too low, using default minimum of 512
INFO: task kworker/u4:0:5 blocked for more than 120 seconds.
      Not tainted 4.15.0-rc2-next-20171205+ #59
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
kworker/u4:0    D15808     5      2 0x80000000
Workqueue: netns cleanup_net
Call Trace:
 context_switch kernel/sched/core.c:2800 [inline]
 __schedule+0x8eb/0x2060 kernel/sched/core.c:3376
 schedule+0xf5/0x430 kernel/sched/core.c:3435
 schedule_preempt_disabled+0x10/0x20 kernel/sched/core.c:3493
 __mutex_lock_common kernel/locking/mutex.c:833 [inline]
 __mutex_lock+0xaad/0x1a80 kernel/locking/mutex.c:893
 mutex_lock_nested+0x16/0x20 kernel/locking/mutex.c:908
 rtnl_lock+0x17/0x20 net/core/rtnetlink.c:74
 tc_action_net_exit include/net/act_api.h:125 [inline]
 bpf_exit_net+0x1a2/0x340 net/sched/act_bpf.c:408
 ops_exit_list.isra.6+0xae/0x150 net/core/net_namespace.c:142
 cleanup_net+0x5c7/0xb60 net/core/net_namespace.c:484
 process_one_work+0xbfd/0x1bc0 kernel/workqueue.c:2113
 worker_thread+0x223/0x1990 kernel/workqueue.c:2247
 kthread+0x37a/0x440 kernel/kthread.c:238
 ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:517

Showing all locks held in the system:
4 locks held by kworker/u4:0/5:
 #0:  ((wq_completion)"%s""netns"){+.+.}, at: [<00000000b9f061a2>] __write_once_size include/linux/compiler.h:212 [inline]
 #0:  ((wq_completion)"%s""netns"){+.+.}, at: [<00000000b9f061a2>] atomic64_set arch/x86/include/asm/atomic64_64.h:34 [inline]
 #0:  ((wq_completion)"%s""netns"){+.+.}, at: [<00000000b9f061a2>] atomic_long_set include/asm-generic/atomic-long.h:57 [inline]
 #0:  ((wq_completion)"%s""netns"){+.+.}, at: [<00000000b9f061a2>] set_work_data kernel/workqueue.c:619 [inline]
 #0:  ((wq_completion)"%s""netns"){+.+.}, at: [<00000000b9f061a2>] set_work_pool_and_clear_pending kernel/workqueue.c:646 [inline]
 #0:  ((wq_completion)"%s""netns"){+.+.}, at: [<00000000b9f061a2>] process_one_work+0xad4/0x1bc0 kernel/workqueue.c:2084
 #1:  (net_cleanup_work){+.+.}, at: [<000000006c7c48a3>] process_one_work+0xb2f/0x1bc0 kernel/workqueue.c:2088
 #2:  (net_mutex){+.+.}, at: [<00000000bf4709f3>] cleanup_net+0x247/0xb60 net/core/net_namespace.c:450
 #3:  (rtnl_mutex){+.+.}, at: [<0000000053390f0b>] rtnl_lock+0x17/0x20 net/core/rtnetlink.c:74
3 locks held by kworker/1:0/17:
 #0:  ((wq_completion)"%s"("ipv6_addrconf")){+.+.}, at: [<00000000b9f061a2>] __write_once_size include/linux/compiler.h:212 [inline]
 #0:  ((wq_completion)"%s"("ipv6_addrconf")){+.+.}, at: [<00000000b9f061a2>] atomic64_set arch/x86/include/asm/atomic64_64.h:34 [inline]
 #0:  ((wq_completion)"%s"("ipv6_addrconf")){+.+.}, at: [<00000000b9f061a2>] atomic_long_set include/asm-generic/atomic-long.h:57 [inline]
 #0:  ((wq_completion)"%s"("ipv6_addrconf")){+.+.}, at: [<00000000b9f061a2>] set_work_data kernel/workqueue.c:619 [inline]
 #0:  ((wq_completion)"%s"("ipv6_addrconf")){+.+.}, at: [<00000000b9f061a2>] set_work_pool_and_clear_pending kernel/workqueue.c:646 [inline]
 #0:  ((wq_completion)"%s"("ipv6_addrconf")){+.+.}, at: [<00000000b9f061a2>] process_one_work+0xad4/0x1bc0 kernel/workqueue.c:2084
 #1:  ((addr_chk_work).work){+.+.}, at: [<000000006c7c48a3>] process_one_work+0xb2f/0x1bc0 kernel/workqueue.c:2088
 #2:  (rtnl_mutex){+.+.}, at: [<0000000053390f0b>] rtnl_lock+0x17/0x20 net/core/rtnetlink.c:74
2 locks held by khungtaskd/675:
 #0:  (rcu_read_lock){....}, at: [<00000000587c8471>] check_hung_uninterruptible_tasks kernel/hung_task.c:175 [inline]
 #0:  (rcu_read_lock){....}, at: [<00000000587c8471>] watchdog+0x1c5/0xd60 kernel/hung_task.c:249
 #1:  (tasklist_lock){.+.+}, at: [<000000005288685e>] debug_show_all_locks+0xd3/0x400 kernel/locking/lockdep.c:4554
1 lock held by rsyslogd/2974:
 #0:  (&f->f_pos_lock){+.+.}, at: [<0000000011e00499>] __fdget_pos+0x131/0x1a0 fs/file.c:770
2 locks held by getty/3056:
 #0:  (&tty->ldisc_sem){++++}, at: [<00000000b9fd70a9>] ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:365
 #1:  (&ldata->atomic_read_lock){+.+.}, at: [<00000000abb3bd08>] n_tty_read+0x2f2/0x1a10 drivers/tty/n_tty.c:2131
2 locks held by getty/3057:
 #0:  (&tty->ldisc_sem){++++}, at: [<00000000b9fd70a9>] ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:365
 #1:  (&ldata->atomic_read_lock){+.+.}, at: [<00000000abb3bd08>] n_tty_read+0x2f2/0x1a10 drivers/tty/n_tty.c:2131
2 locks held by getty/3058:
 #0:  (&tty->ldisc_sem){++++}, at: [<00000000b9fd70a9>] ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:365
 #1:  (&ldata->atomic_read_lock){+.+.}, at: [<00000000abb3bd08>] n_tty_read+0x2f2/0x1a10 drivers/tty/n_tty.c:2131
2 locks held by getty/3059:
 #0:  (&tty->ldisc_sem){++++}, at: [<00000000b9fd70a9>] ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:365
 #1:  (&ldata->atomic_read_lock){+.+.}, at: [<00000000abb3bd08>] n_tty_read+0x2f2/0x1a10 drivers/tty/n_tty.c:2131
2 locks held by getty/3060:
 #0:  (&tty->ldisc_sem){++++}, at: [<00000000b9fd70a9>] ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:365
 #1:  (&ldata->atomic_read_lock){+.+.}, at: [<00000000abb3bd08>] n_tty_read+0x2f2/0x1a10 drivers/tty/n_tty.c:2131
2 locks held by getty/3061:
 #0:  (&tty->ldisc_sem){++++}, at: [<00000000b9fd70a9>] ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:365
 #1:  (&ldata->atomic_read_lock){+.+.}, at: [<00000000abb3bd08>] n_tty_read+0x2f2/0x1a10 drivers/tty/n_tty.c:2131
2 locks held by getty/3062:
 #0:  (&tty->ldisc_sem){++++}, at: [<00000000b9fd70a9>] ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:365
 #1:  (&ldata->atomic_read_lock){+.+.}, at: [<00000000abb3bd08>] n_tty_read+0x2f2/0x1a10 drivers/tty/n_tty.c:2131

=============================================

NMI backtrace for cpu 0
CPU: 0 PID: 675 Comm: khungtaskd Not tainted 4.15.0-rc2-next-20171205+ #59
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Call Trace:
 __dump_stack lib/dump_stack.c:17 [inline]
 dump_stack+0x194/0x257 lib/dump_stack.c:53
 nmi_cpu_backtrace+0x1d2/0x210 lib/nmi_backtrace.c:103
 nmi_trigger_cpumask_backtrace+0x122/0x180 lib/nmi_backtrace.c:62
 arch_trigger_cpumask_backtrace+0x14/0x20 arch/x86/kernel/apic/hw_nmi.c:38
 trigger_all_cpu_backtrace include/linux/nmi.h:138 [inline]
 check_hung_task kernel/hung_task.c:132 [inline]
 check_hung_uninterruptible_tasks kernel/hung_task.c:190 [inline]
 watchdog+0x90c/0xd60 kernel/hung_task.c:249
 kthread+0x37a/0x440 kernel/kthread.c:238
 ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:517
Sending NMI from CPU 0 to CPUs 1:
NMI backtrace for cpu 1
CPU: 1 PID: 13156 Comm: syz-executor7 Not tainted 4.15.0-rc2-next-20171205+ #59
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
task: 000000005209c120 task.stack: 00000000ffaab0e8
RIP: 0010:inb arch/x86/include/asm/io.h:348 [inline]
RIP: 0010:io_serial_in+0x6b/0x90 drivers/tty/serial/8250/8250_port.c:434
RSP: 0018:ffff8801c0a16e70 EFLAGS: 00000002
RAX: dffffc0000000000 RBX: 00000000000003fd RCX: 0000000000000000
RDX: 00000000000003fd RSI: ffffc90003745000 RDI: ffffffff87cf1a40
RBP: ffff8801c0a16e80 R08: 0000000000000005 R09: 000000000000000c
R10: 0000000000000000 R11: ffffffff8748dd20 R12: ffffffff87cf1a00
R13: 0000000000000020 R14: fffffbfff0f9e387 R15: fffffbfff0f9e34a
FS:  00007f6d52e3f700(0000) GS:ffff8801db500000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 000000c42005de80 CR3: 00000001c368a000 CR4: 00000000001406e0
DR0: 0000000020000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000600
Call Trace:
 serial_in drivers/tty/serial/8250/8250.h:111 [inline]
 wait_for_xmitr+0x93/0x1e0 drivers/tty/serial/8250/8250_port.c:2033
 serial8250_console_putchar+0x1f/0x60 drivers/tty/serial/8250/8250_port.c:3170
 uart_console_write+0xac/0xe0 drivers/tty/serial/serial_core.c:1858
 serial8250_console_write+0x647/0xa20 drivers/tty/serial/8250/8250_port.c:3236
 univ8250_console_write+0x5f/0x70 drivers/tty/serial/8250/8250_core.c:590
 call_console_drivers kernel/printk/printk.c:1574 [inline]
 console_unlock+0x788/0xd70 kernel/printk/printk.c:2233
 vprintk_emit+0x4ad/0x590 kernel/printk/printk.c:1757
 vprintk_default+0x28/0x30 kernel/printk/printk.c:1796
 vprintk_func+0x57/0xc0 kernel/printk/printk_safe.c:379
 printk+0xaa/0xca kernel/printk/printk.c:1829
 nla_parse+0x374/0x3d0 lib/nlattr.c:257
 nlmsg_parse include/net/netlink.h:398 [inline]
 nl80211_dump_wiphy_parse.isra.37.constprop.83+0x138/0x5c0 net/wireless/nl80211.c:1920
 nl80211_dump_interface+0x596/0x820 net/wireless/nl80211.c:2660
 genl_lock_dumpit+0x68/0x90 net/netlink/genetlink.c:480
 netlink_dump+0x48c/0xce0 net/netlink/af_netlink.c:2186
 __netlink_dump_start+0x4f0/0x6d0 net/netlink/af_netlink.c:2283
 genl_family_rcv_msg+0xd27/0xfc0 net/netlink/genetlink.c:548
 genl_rcv_msg+0xb2/0x140 net/netlink/genetlink.c:624
 netlink_rcv_skb+0x216/0x440 net/netlink/af_netlink.c:2405
 genl_rcv+0x28/0x40 net/netlink/genetlink.c:635
 netlink_unicast_kernel net/netlink/af_netlink.c:1272 [inline]
 netlink_unicast+0x4e8/0x6f0 net/netlink/af_netlink.c:1298
 netlink_sendmsg+0xa4a/0xe70 net/netlink/af_netlink.c:1861
 sock_sendmsg_nosec net/socket.c:636 [inline]
 sock_sendmsg+0xca/0x110 net/socket.c:646
 sock_write_iter+0x320/0x5e0 net/socket.c:915
 call_write_iter include/linux/fs.h:1776 [inline]
 new_sync_write fs/read_write.c:469 [inline]
 __vfs_write+0x68a/0x970 fs/read_write.c:482
 vfs_write+0x18f/0x510 fs/read_write.c:544
 SYSC_write fs/read_write.c:589 [inline]
 SyS_write+0xef/0x220 fs/read_write.c:581
 entry_SYSCALL_64_fastpath+0x1f/0x96
RIP: 0033:0x4529d9
RSP: 002b:00007f6d52e3ec58 EFLAGS: 00000212 ORIG_RAX: 0000000000000001
RAX: ffffffffffffffda RBX: 00007f6d52e3f700 RCX: 00000000004529d9
RDX: 0000000000000024 RSI: 0000000020454000 RDI: 0000000000000016
RBP: 0000000000000000 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000212 R12: 0000000000000000
R13: 0000000000a6f7ff R14: 00007f6d52e3f9c0 R15: 0000000000000000
Code: 24 d9 00 00 00 49 8d 7c 24 40 48 b8 00 00 00 00 00 fc ff df 48 89 fa 48 c1 ea 03 d3 e3 80 3c 02 00 75 17 41 03 5c 24 40 89 da ec <5b> 0f b6 c0 41 5c 5d c3 e8 38 b0 18 ff eb c2 e8 91 b0 18 ff eb 

Crashes (1):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2017/12/05 17:56 linux-next 7ceb97a071e8 de212f1a .config console log report ci-upstream-next-kasan-gce
* Struck through repros no longer work on HEAD.