On Fri, Jan 11, 2019 at 11:09 AM syzbot <syzbot+3863f23ed69a006cf...@syzkaller.appspotmail.com> wrote: > > Hello, > > syzbot found the following crash on: > > HEAD commit: 1bdbe2274920 Merge tag 'vfio-v5.0-rc2' of git://github.com.. > git tree: upstream > console output: https://syzkaller.appspot.com/x/log.txt?x=100dc607400000 > kernel config: https://syzkaller.appspot.com/x/.config?x=edf1c3031097c304 > dashboard link: https://syzkaller.appspot.com/bug?extid=3863f23ed69a006cfa87 > compiler: gcc (GCC) 9.0.0 20181231 (experimental) > > Unfortunately, I don't have any reproducer for this crash yet. > > IMPORTANT: if you fix the bug, please add the following tag to the commit: > Reported-by: syzbot+3863f23ed69a006cf...@syzkaller.appspotmail.com > > INFO: task syz-executor5:13532 blocked for more than 140 seconds. > Not tainted 5.0.0-rc1+ #19 > "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. > syz-executor5 D25192 13532 8541 0x00000004 > Call Trace: > context_switch kernel/sched/core.c:2831 [inline] > __schedule+0x897/0x1e60 kernel/sched/core.c:3472 > schedule+0xfe/0x350 kernel/sched/core.c:3516 > schedule_preempt_disabled+0x13/0x20 kernel/sched/core.c:3574 > __mutex_lock_common kernel/locking/mutex.c:1002 [inline] > __mutex_lock+0xa3b/0x1670 kernel/locking/mutex.c:1072 > mutex_lock_nested+0x16/0x20 kernel/locking/mutex.c:1087 > genl_lock net/netlink/genetlink.c:33 [inline] > genl_family_rcv_msg+0xec6/0x11a0 net/netlink/genetlink.c:550 > genl_rcv_msg+0xca/0x16c net/netlink/genetlink.c:626 > netlink_rcv_skb+0x17d/0x410 net/netlink/af_netlink.c:2477 > genl_rcv+0x29/0x40 net/netlink/genetlink.c:637 > netlink_unicast_kernel net/netlink/af_netlink.c:1310 [inline] > netlink_unicast+0x574/0x770 net/netlink/af_netlink.c:1336 > netlink_sendmsg+0xa05/0xf90 net/netlink/af_netlink.c:1917 > sock_sendmsg_nosec net/socket.c:621 [inline] > sock_sendmsg+0xdd/0x130 net/socket.c:631 > ___sys_sendmsg+0x7ec/0x910 net/socket.c:2116 > __sys_sendmsg+0x112/0x270 net/socket.c:2154 > __do_sys_sendmsg net/socket.c:2163 [inline] > __se_sys_sendmsg net/socket.c:2161 [inline] > __x64_sys_sendmsg+0x78/0xb0 net/socket.c:2161 > do_syscall_64+0x1a3/0x800 arch/x86/entry/common.c:290 > entry_SYSCALL_64_after_hwframe+0x49/0xbe > RIP: 0033:0x457ec9 > Code: Bad RIP value. > RSP: 002b:00007f9aad580c78 EFLAGS: 00000246 ORIG_RAX: 000000000000002e > RAX: ffffffffffffffda RBX: 0000000000000003 RCX: 0000000000457ec9 > RDX: 0000000000000000 RSI: 0000000020000280 RDI: 0000000000000003 > RBP: 000000000073bf00 R08: 0000000000000000 R09: 0000000000000000 > R10: 0000000000000000 R11: 0000000000000246 R12: 00007f9aad5816d4 > R13: 00000000004c52f9 R14: 00000000004d8d58 R15: 00000000ffffffff > > Showing all locks held in the system: > 1 lock held by khungtaskd/1040: > #0: 0000000007c9c70b (rcu_read_lock){....}, at: > debug_show_all_locks+0xc6/0x41d kernel/locking/lockdep.c:4389 > 1 lock held by rsyslogd/8364: > #0: 00000000ccbb3d9d (&f->f_pos_lock){+.+.}, at: __fdget_pos+0x1b3/0x1f0 > fs/file.c:795 > 2 locks held by getty/8486: > #0: 00000000da7bf077 (&tty->ldisc_sem){++++}, at: > ldsem_down_read+0x33/0x40 drivers/tty/tty_ldsem.c:341 > #1: 000000002a145a49 (&ldata->atomic_read_lock){+.+.}, at: > n_tty_read+0x30a/0x1eb0 drivers/tty/n_tty.c:2154 > 2 locks held by getty/8487: > #0: 000000005a9ea624 (&tty->ldisc_sem){++++}, at: > ldsem_down_read+0x33/0x40 drivers/tty/tty_ldsem.c:341 > #1: 00000000481e0684 (&ldata->atomic_read_lock){+.+.}, at: > n_tty_read+0x30a/0x1eb0 drivers/tty/n_tty.c:2154 > 2 locks held by getty/8488: > #0: 00000000372aa326 (&tty->ldisc_sem){++++}, at: > ldsem_down_read+0x33/0x40 drivers/tty/tty_ldsem.c:341 > #1: 000000001edb2f7b (&ldata->atomic_read_lock){+.+.}, at: > n_tty_read+0x30a/0x1eb0 drivers/tty/n_tty.c:2154 > 2 locks held by getty/8489: > #0: 0000000042afc2f1 (&tty->ldisc_sem){++++}, at: > ldsem_down_read+0x33/0x40 drivers/tty/tty_ldsem.c:341 > #1: 0000000039788daa (&ldata->atomic_read_lock){+.+.}, at: > n_tty_read+0x30a/0x1eb0 drivers/tty/n_tty.c:2154 > 2 locks held by getty/8490: > #0: 000000009f514e08 (&tty->ldisc_sem){++++}, at: > ldsem_down_read+0x33/0x40 drivers/tty/tty_ldsem.c:341 > #1: 00000000e7f16282 (&ldata->atomic_read_lock){+.+.}, at: > n_tty_read+0x30a/0x1eb0 drivers/tty/n_tty.c:2154 > 2 locks held by getty/8491: > #0: 0000000096cc811b (&tty->ldisc_sem){++++}, at: > ldsem_down_read+0x33/0x40 drivers/tty/tty_ldsem.c:341 > #1: 00000000090b784c (&ldata->atomic_read_lock){+.+.}, at: > n_tty_read+0x30a/0x1eb0 drivers/tty/n_tty.c:2154 > 2 locks held by getty/8492: > #0: 00000000b1aedf80 (&tty->ldisc_sem){++++}, at: > ldsem_down_read+0x33/0x40 drivers/tty/tty_ldsem.c:341 > #1: 000000001005e743 (&ldata->atomic_read_lock){+.+.}, at: > n_tty_read+0x30a/0x1eb0 drivers/tty/n_tty.c:2154 > 4 locks held by syz-executor1/13529: > 2 locks held by syz-executor5/13532: > #0: 0000000060a34b7c (cb_lock){++++}, at: genl_rcv+0x1a/0x40 > net/netlink/genetlink.c:636 > #1: 000000003d185120 (genl_mutex){+.+.}, at: genl_lock > net/netlink/genetlink.c:33 [inline] > #1: 000000003d185120 (genl_mutex){+.+.}, at: > genl_family_rcv_msg+0xec6/0x11a0 net/netlink/genetlink.c:550 > > ============================================= > > NMI backtrace for cpu 1 > CPU: 1 PID: 1040 Comm: khungtaskd Not tainted 5.0.0-rc1+ #19 > 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+0x1db/0x2d0 lib/dump_stack.c:113 > nmi_cpu_backtrace.cold+0x63/0xa4 lib/nmi_backtrace.c:101 > nmi_trigger_cpumask_backtrace+0x1be/0x236 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:203 [inline] > watchdog+0xbbb/0x1170 kernel/hung_task.c:287 > kthread+0x357/0x430 kernel/kthread.c:246 > ret_from_fork+0x3a/0x50 arch/x86/entry/entry_64.S:352 > Sending NMI from CPU 1 to CPUs 0: > INFO: NMI handler (nmi_cpu_backtrace_handler) took too long to run: 1.554 > msecs > NMI backtrace for cpu 0 > CPU: 0 PID: 13529 Comm: syz-executor1 Not tainted 5.0.0-rc1+ #19 > Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS > Google 01/01/2011 > RIP: 0010:net_generic include/net/netns/generic.h:45 [inline] > RIP: 0010:tipc_sk_lookup+0xb79/0xf80 net/tipc/socket.c:2783 > Code: d3 f7 88 be 60 02 00 00 48 c7 c7 c0 d3 f7 88 c6 05 fa dc ab 02 01 e8 > 24 4e b8 f9 e9 cb f5 ff ff e8 1c cd d5 f9 e8 b7 0a bf f9 <31> ff 41 89 c5 > 89 c6 e8 8b ce d5 f9 45 85 ed 0f 85 4b f6 ff ff e8 > RSP: 0018:ffff88804d7b6aa8 EFLAGS: 00000292 > RAX: 0000000000000001 RBX: ffff8880928504c0 RCX: dffffc0000000000 > RDX: dffffc0000000000 RSI: 0000000000000000 RDI: 0000000000000286 > RBP: ffff88804d7b6c78 R08: ffff88809263a240 R09: ffffed1015cc5b90 > R10: ffffed1015cc5b8f R11: ffff8880ae62dc7b R12: 0000000000000045 > R13: 0000000000000000 R14: ffff88804d7b6c50 R15: ffff88804d7b6f20 > FS: 00007f86b0907700(0000) GS:ffff8880ae600000(0000) knlGS:0000000000000000 > CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 > CR2: 000000c41f9bce6f CR3: 00000000a0ec2000 CR4: 00000000001406f0 > DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 > DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 > Call Trace: > tipc_nl_publ_dump+0x209/0xf40 net/tipc/socket.c:3591
This looks like #syz dup: INFO: rcu detected stall in tipc_sk_lookup Somehow the stall detector did not fire in tipc_nl_compat_dumpit stack, yet the rcu stall timeout is set to smaller value than the task hung detector timeout... > __tipc_nl_compat_dumpit.isra.0+0x261/0xa80 net/tipc/netlink_compat.c:196 > tipc_nl_compat_publ_dump net/tipc/netlink_compat.c:927 [inline] > tipc_nl_compat_sk_dump+0x6ac/0xd40 net/tipc/netlink_compat.c:978 > __tipc_nl_compat_dumpit.isra.0+0x383/0xa80 net/tipc/netlink_compat.c:205 > tipc_nl_compat_dumpit+0x1f4/0x440 net/tipc/netlink_compat.c:270 > tipc_nl_compat_handle net/tipc/netlink_compat.c:1152 [inline] > tipc_nl_compat_recv+0xed9/0x18b0 net/tipc/netlink_compat.c:1215 > genl_family_rcv_msg+0x80d/0x11a0 net/netlink/genetlink.c:601 > genl_rcv_msg+0xca/0x16c net/netlink/genetlink.c:626 > netlink_rcv_skb+0x17d/0x410 net/netlink/af_netlink.c:2477 > genl_rcv+0x29/0x40 net/netlink/genetlink.c:637 > netlink_unicast_kernel net/netlink/af_netlink.c:1310 [inline] > netlink_unicast+0x574/0x770 net/netlink/af_netlink.c:1336 > netlink_sendmsg+0xa05/0xf90 net/netlink/af_netlink.c:1917 > sock_sendmsg_nosec net/socket.c:621 [inline] > sock_sendmsg+0xdd/0x130 net/socket.c:631 > ___sys_sendmsg+0x7ec/0x910 net/socket.c:2116 > __sys_sendmsg+0x112/0x270 net/socket.c:2154 > __do_sys_sendmsg net/socket.c:2163 [inline] > __se_sys_sendmsg net/socket.c:2161 [inline] > __x64_sys_sendmsg+0x78/0xb0 net/socket.c:2161 > do_syscall_64+0x1a3/0x800 arch/x86/entry/common.c:290 > entry_SYSCALL_64_after_hwframe+0x49/0xbe > RIP: 0033:0x457ec9 > Code: 6d b7 fb ff c3 66 2e 0f 1f 84 00 00 00 00 00 66 90 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 3b b7 fb ff c3 66 2e 0f 1f 84 00 00 00 00 > RSP: 002b:00007f86b0906c78 EFLAGS: 00000246 ORIG_RAX: 000000000000002e > RAX: ffffffffffffffda RBX: 0000000000000003 RCX: 0000000000457ec9 > RDX: 0000000000000000 RSI: 0000000020000500 RDI: 0000000000000007 > RBP: 000000000073bf00 R08: 0000000000000000 R09: 0000000000000000 > R10: 0000000000000000 R11: 0000000000000246 R12: 00007f86b09076d4 > R13: 00000000004cb688 R14: 00000000004d8ab8 R15: 00000000ffffffff > > > --- > 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 syzkal...@googlegroups.com. > > syzbot will keep track of this bug report. See: > https://goo.gl/tpsmEJ#bug-status-tracking for how to communicate with > syzbot. > > -- > You received this message because you are subscribed to the Google Groups > "syzkaller-bugs" group. > To unsubscribe from this group and stop receiving emails from it, send an > email to syzkaller-bugs+unsubscr...@googlegroups.com. > To view this discussion on the web visit > https://groups.google.com/d/msgid/syzkaller-bugs/0000000000007966c6057f2be2aa%40google.com. > For more options, visit https://groups.google.com/d/optout.
