On 10/13/19 9:42 PM, syzbot wrote: > Hello, > > syzbot found the following crash on: > > HEAD commit: c208bdb9 tcp: improve recv_skip_hint for tcp_zerocopy_rece.. > git tree: net-next > console output: https://syzkaller.appspot.com/x/log.txt?x=15b6133b600000 > kernel config: https://syzkaller.appspot.com/x/.config?x=d9be300620399522 > dashboard link: https://syzkaller.appspot.com/bug?extid=cf0adbb9c28c8866c788 > compiler: gcc (GCC) 9.0.0 20181231 (experimental) > syz repro: https://syzkaller.appspot.com/x/repro.syz?x=1548666f600000 > C reproducer: https://syzkaller.appspot.com/x/repro.c?x=11957d3b600000 > > IMPORTANT: if you fix the bug, please add the following tag to the commit: > Reported-by: syzbot+cf0adbb9c28c8866c788@xxxxxxxxxxxxxxxxxxxxxxxxx > > INFO: task kworker/0:2:2913 blocked for more than 143 seconds. > Not tainted 5.4.0-rc1+ #0 > "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. > kworker/0:2 D27000 2913 2 0x80004000 > Workqueue: ipv6_addrconf addrconf_verify_work > Call Trace: > context_switch kernel/sched/core.c:3384 [inline] > __schedule+0x94f/0x1e70 kernel/sched/core.c:4069 > schedule+0xd9/0x260 kernel/sched/core.c:4136 > schedule_preempt_disabled+0x13/0x20 kernel/sched/core.c:4195 > __mutex_lock_common kernel/locking/mutex.c:1033 [inline] > __mutex_lock+0x7b0/0x13c0 kernel/locking/mutex.c:1103 > mutex_lock_nested+0x16/0x20 kernel/locking/mutex.c:1118 > rtnl_lock+0x17/0x20 net/core/rtnetlink.c:72 > addrconf_verify_work+0xe/0x20 net/ipv6/addrconf.c:4520 > process_one_work+0x9af/0x1740 kernel/workqueue.c:2269 > worker_thread+0x98/0xe40 kernel/workqueue.c:2415 > kthread+0x361/0x430 kernel/kthread.c:255 > ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:352 > > Showing all locks held in the system: > 1 lock held by khungtaskd/1054: > #0: ffffffff88faae40 (rcu_read_lock){....}, at: debug_show_all_locks+0x5f/0x27e kernel/locking/lockdep.c:5337 > 3 locks held by kworker/0:2/2913: > #0: ffff888216019428 ((wq_completion)ipv6_addrconf){+.+.}, at: __write_once_size include/linux/compiler.h:226 [inline] > #0: ffff888216019428 ((wq_completion)ipv6_addrconf){+.+.}, at: arch_atomic64_set arch/x86/include/asm/atomic64_64.h:34 [inline] > #0: ffff888216019428 ((wq_completion)ipv6_addrconf){+.+.}, at: atomic64_set include/asm-generic/atomic-instrumented.h:855 [inline] > #0: ffff888216019428 ((wq_completion)ipv6_addrconf){+.+.}, at: atomic_long_set include/asm-generic/atomic-long.h:40 [inline] > #0: ffff888216019428 ((wq_completion)ipv6_addrconf){+.+.}, at: set_work_data kernel/workqueue.c:620 [inline] > #0: ffff888216019428 ((wq_completion)ipv6_addrconf){+.+.}, at: set_work_pool_and_clear_pending kernel/workqueue.c:647 [inline] > #0: ffff888216019428 ((wq_completion)ipv6_addrconf){+.+.}, at: process_one_work+0x88b/0x1740 kernel/workqueue.c:2240 > #1: ffff8880a05b7dc0 ((addr_chk_work).work){+.+.}, at: process_one_work+0x8c1/0x1740 kernel/workqueue.c:2244 > #2: ffffffff89993b20 (rtnl_mutex){+.+.}, at: rtnl_lock+0x17/0x20 net/core/rtnetlink.c:72 > 1 lock held by rsyslogd/8744: > #0: ffff8880899fa120 (&f->f_pos_lock){+.+.}, at: __fdget_pos+0xee/0x110 fs/file.c:801 > 2 locks held by getty/8833: > #0: ffff888090baedd0 (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x33/0x40 drivers/tty/tty_ldsem.c:340 > #1: ffffc90005f292e0 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x232/0x1c10 drivers/tty/n_tty.c:2156 > 2 locks held by getty/8834: > #0: ffff88808d0f6dd0 (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x33/0x40 drivers/tty/tty_ldsem.c:340 > #1: ffffc90005f392e0 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x232/0x1c10 drivers/tty/n_tty.c:2156 > 2 locks held by getty/8835: > #0: ffff888090148e10 (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x33/0x40 drivers/tty/tty_ldsem.c:340 > #1: ffffc90005f252e0 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x232/0x1c10 drivers/tty/n_tty.c:2156 > 2 locks held by getty/8836: > #0: ffff8880a7ab3750 (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x33/0x40 drivers/tty/tty_ldsem.c:340 > #1: ffffc90005f412e0 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x232/0x1c10 drivers/tty/n_tty.c:2156 > 2 locks held by getty/8837: > #0: ffff8880a7accf10 (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x33/0x40 drivers/tty/tty_ldsem.c:340 > #1: ffffc90005f3d2e0 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x232/0x1c10 drivers/tty/n_tty.c:2156 > 2 locks held by getty/8838: > #0: ffff88808d0f7650 (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x33/0x40 drivers/tty/tty_ldsem.c:340 > #1: ffffc90005f352e0 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x232/0x1c10 drivers/tty/n_tty.c:2156 > 2 locks held by getty/8839: > #0: ffff88808d162bd0 (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x33/0x40 drivers/tty/tty_ldsem.c:340 > #1: ffffc90005f112e0 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x232/0x1c10 drivers/tty/n_tty.c:2156 > 1 lock held by syz-executor910/8859: > > ============================================= > > NMI backtrace for cpu 0 > CPU: 0 PID: 1054 Comm: khungtaskd Not tainted 5.4.0-rc1+ #0 > Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 > Call Trace: > __dump_stack lib/dump_stack.c:77 [inline] > dump_stack+0x172/0x1f0 lib/dump_stack.c:113 > nmi_cpu_backtrace.cold+0x70/0xb2 lib/nmi_backtrace.c:101 > nmi_trigger_cpumask_backtrace+0x23b/0x28b 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:146 [inline] > check_hung_uninterruptible_tasks kernel/hung_task.c:205 [inline] > watchdog+0x9d0/0xef0 kernel/hung_task.c:289 > kthread+0x361/0x430 kernel/kthread.c:255 > ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:352 > Sending NMI from CPU 0 to CPUs 1: > NMI backtrace for cpu 1 > CPU: 1 PID: 8859 Comm: syz-executor910 Not tainted 5.4.0-rc1+ #0 > Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 > RIP: 0010:arch_local_save_flags arch/x86/include/asm/paravirt.h:751 [inline] > RIP: 0010:lockdep_hardirqs_off+0x1df/0x2e0 kernel/locking/lockdep.c:3453 > Code: 5c 08 00 00 5b 41 5c 41 5d 5d c3 48 c7 c0 58 1d f3 88 48 ba 00 00 00 00 00 fc ff df 48 c1 e8 03 80 3c 10 00 0f 85 d3 00 00 00 <48> 83 3d 21 9e 99 07 00 0f 84 b9 00 00 00 9c 58 0f 1f 44 00 00 f6 > RSP: 0018:ffff8880a6f3f1b8 EFLAGS: 00000046 > RAX: 1ffffffff11e63ab RBX: ffff88808c9c6080 RCX: 0000000000000000 > RDX: dffffc0000000000 RSI: 0000000000000000 RDI: ffff88808c9c6914 > RBP: ffff8880a6f3f1d0 R08: ffff88808c9c6080 R09: fffffbfff16be5d1 > R10: fffffbfff16be5d0 R11: 0000000000000003 R12: ffffffff8746591f > R13: ffff88808c9c6080 R14: ffffffff8746591f R15: 0000000000000003 > FS: 00000000011e4880(0000) GS:ffff8880ae900000(0000) knlGS:0000000000000000 > CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 > CR2: ffffffffff600400 CR3: 00000000a8920000 CR4: 00000000001406e0 > DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 > DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 > Call Trace: > trace_hardirqs_off+0x62/0x240 kernel/trace/trace_preemptirq.c:45 > __raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:108 [inline] > _raw_spin_lock_irqsave+0x6f/0xcd kernel/locking/spinlock.c:159 > __wake_up_common_lock+0xc8/0x150 kernel/sched/wait.c:122 > __wake_up+0xe/0x10 kernel/sched/wait.c:142 > netlink_unlock_table net/netlink/af_netlink.c:466 [inline] > netlink_unlock_table net/netlink/af_netlink.c:463 [inline] > netlink_broadcast_filtered+0x705/0xb80 net/netlink/af_netlink.c:1514 > netlink_broadcast+0x3a/0x50 net/netlink/af_netlink.c:1534 > rtnetlink_send+0xdd/0x110 net/core/rtnetlink.c:714 > tcf_add_notify net/sched/act_api.c:1343 [inline] > tcf_action_add+0x243/0x370 net/sched/act_api.c:1362 > tc_ctl_action+0x3b5/0x4bc net/sched/act_api.c:1410 > rtnetlink_rcv_msg+0x463/0xb00 net/core/rtnetlink.c:5386 > netlink_rcv_skb+0x177/0x450 net/netlink/af_netlink.c:2477 > rtnetlink_rcv+0x1d/0x30 net/core/rtnetlink.c:5404 > netlink_unicast_kernel net/netlink/af_netlink.c:1302 [inline] > netlink_unicast+0x531/0x710 net/netlink/af_netlink.c:1328 > netlink_sendmsg+0x8a5/0xd60 net/netlink/af_netlink.c:1917 > sock_sendmsg_nosec net/socket.c:637 [inline] > sock_sendmsg+0xd7/0x130 net/socket.c:657 > ___sys_sendmsg+0x803/0x920 net/socket.c:2311 > __sys_sendmsg+0x105/0x1d0 net/socket.c:2356 > __do_sys_sendmsg net/socket.c:2365 [inline] > __se_sys_sendmsg net/socket.c:2363 [inline] > __x64_sys_sendmsg+0x78/0xb0 net/socket.c:2363 > do_syscall_64+0xfa/0x760 arch/x86/entry/common.c:290 > entry_SYSCALL_64_after_hwframe+0x49/0xbe > RIP: 0033:0x440939 > Code: 18 89 d0 c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 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 0f 83 fb 13 fc ff c3 66 2e 0f 1f 84 00 00 00 00 > RSP: 002b:00007ffeea8a8d98 EFLAGS: 00000246 ORIG_RAX: 000000000000002e > RAX: ffffffffffffffda RBX: 00000000004002c8 RCX: 0000000000440939 > RDX: 0000000020000010 RSI: 0000000020001480 RDI: 0000000000000003 > RBP: 00000000006cb018 R08: 0000000000000002 R09: 00000000004002c8 > R10: 0000000000000008 R11: 0000000000000246 R12: 00000000004021c0 > R13: 0000000000402250 R14: 0000000000000000 R15: 0000000000000000 > > > --- > This bug 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@xxxxxxxxxxxxxxxx. > > syzbot will keep track of this bug report. See: > https://goo.gl/tpsmEJ#status for how to communicate with syzbot. > syzbot can test patches for this bug, for details see: > https://goo.gl/tpsmEJ#testing-patches Infinite loop because tcf_add_notify() returns -EAGAIN as the message can not be delivered to the socket, since its SO_RCVBUF has been set to 0. Perhaps we need this patch ? diff --git a/net/sched/act_api.c b/net/sched/act_api.c index 194aed41db7f930d345463b8cecf915db0d056f1..0e7de888533abde7201afa4a7f3ac3c98ed40a35 100644 --- a/net/sched/act_api.c +++ b/net/sched/act_api.c @@ -1362,8 +1362,11 @@ static int tcf_action_add(struct net *net, struct nlattr *nla, int ret = 0; struct tc_action *actions[TCA_ACT_MAX_PRIO] = {}; - ret = tcf_action_init(net, NULL, nla, NULL, NULL, ovr, 0, actions, - &attr_size, true, extack); + do { + ret = tcf_action_init(net, NULL, nla, NULL, NULL, ovr, 0, + actions, &attr_size, true, extack); + } while (ret == -EAGAIN); + if (ret < 0) return ret; ret = tcf_add_notify(net, n, actions, portid, attr_size, extack); @@ -1413,11 +1416,8 @@ static int tc_ctl_action(struct sk_buff *skb, struct nlmsghdr *n, */ if (n->nlmsg_flags & NLM_F_REPLACE) ovr = 1; -replay: ret = tcf_action_add(net, tca[TCA_ACT_TAB], n, portid, ovr, extack); - if (ret == -EAGAIN) - goto replay; break; case RTM_DELACTION: ret = tca_action_gd(net, tca[TCA_ACT_TAB], n,
