INFO: rcu detected stall in raw_sendmsg

[syzbot]

Hello,

syzbot hit the following crash on net-next commit
9515a2e082f91457db0ecff4b65371d0fb5d9aad (Thu Jan 25 03:37:38 2018 +0000)
net/ipv4: Allow send to local broadcast from a socket bound to a VRF

So far this crash happened 3 times on net-next.
Unfortunately, I don't have any reproducer for this crash yet.
Raw console output is attached.
compiler: gcc (GCC) 7.1.1 20170620
.config is attached.
CC: [andriy.s...@linux.intel.com er...@anholt.net
gre...@linuxfoundation.org jan.k...@siemens.com jsl...@suse.com
linux-...@vger.kernel.org linux-...@vger.kernel.org
marc_g...@sigmadesigns.com ph...@raspberrypi.org rafae...@gmail.com
sean...@mediatek.com tomas...@vaisala.com]

IMPORTANT: if you fix the bug, please add the following tag to the commit:
Reported-by: syzbot+6fe319...@syzkaller.appspotmail.com
It will help syzbot understand when the bug is fixed. See footer for
details.
If you forward the report, please keep this part and the footer.

netlink: 9 bytes leftover after parsing attributes in process
`syz-executor4'.
INFO: rcu_sched self-detected stall on CPU
INFO: rcu_sched detected stalls on CPUs/tasks:
0-....: (125000 ticks this GP) idle=e96/140000000000001/0
softirq=1667512/1667512 fqs=31231
(detected by 1, t=125002 jiffies, g=968435, c=968434, q=4468)
Sending NMI from CPU 1 to CPUs 0:
NMI backtrace for cpu 0
CPU: 0 PID: 8070 Comm: syz-executor6 Not tainted 4.15.0-rc9+ #210
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS
Google 01/01/2011
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:ffff8801db206ff8 EFLAGS: 00000002
RAX: dffffc0000000000 RBX: 00000000000003fd RCX: 0000000000000000
RDX: 00000000000003fd RSI: 0000000000000005 RDI: ffffffff88872f58
RBP: ffff8801db207008 R08: 1ffff1003b640d57 R09: 000000000000000c
R10: ffff8801db206f78 R11: 0000000000000040 R12: ffffffff88872f20
R13: 0000000000000020 R14: fffffbfff110e629 R15: fffffbfff110e5ed
FS: 00007f071450f700(0000) GS:ffff8801db200000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000000000717b34 CR3: 00000001cc813005 CR4: 00000000001606f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
<IRQ>
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+0x64f/0xa40
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+0x788/0xd80 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
print_cpu_stall_info_begin kernel/rcu/tree_plugin.h:1657 [inline]
print_cpu_stall kernel/rcu/tree.c:1594 [inline]
check_cpu_stall.isra.61+0x845/0x15b0 kernel/rcu/tree.c:1676
__rcu_pending kernel/rcu/tree.c:3440 [inline]
rcu_pending kernel/rcu/tree.c:3502 [inline]
rcu_check_callbacks+0x256/0xd00 kernel/rcu/tree.c:2842
update_process_times+0x30/0x60 kernel/time/timer.c:1628
tick_sched_handle+0x85/0x160 kernel/time/tick-sched.c:162
tick_sched_timer+0x42/0x120 kernel/time/tick-sched.c:1194
__run_hrtimer kernel/time/hrtimer.c:1211 [inline]
__hrtimer_run_queues+0x358/0xe20 kernel/time/hrtimer.c:1275
hrtimer_interrupt+0x1c2/0x5e0 kernel/time/hrtimer.c:1309
local_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1025 [inline]
smp_apic_timer_interrupt+0x14a/0x700 arch/x86/kernel/apic/apic.c:1050
apic_timer_interrupt+0xa9/0xb0 arch/x86/entry/entry_64.S:937
</IRQ>
RIP: 0010:__sanitizer_cov_trace_pc+0x0/0x50
RSP: 0018:ffff8801af1c7828 EFLAGS: 00000246 ORIG_RAX: ffffffffffffff11
RAX: 0000000000000000 RBX: ffff8801c4b8bb00 RCX: ffffffff84acc87d
RDX: 0000000000000004 RSI: ffffc90003225000 RDI: ffff8801b4eb6b50
RBP: ffff8801af1c7868 R08: 0000000000000001 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000000 R12: ffff8801b4eb6a00
R13: dffffc0000000000 R14: ffffed003897177f R15: ffff8801c4b8bbfc
dst_confirm_neigh include/net/dst.h:419 [inline]
raw_sendmsg+0xece/0x23b0 net/ipv4/raw.c:702
inet_sendmsg+0x11f/0x5e0 net/ipv4/af_inet.c:764
sock_sendmsg_nosec net/socket.c:630 [inline]
sock_sendmsg+0xca/0x110 net/socket.c:640
SYSC_sendto+0x361/0x5c0 net/socket.c:1747
SyS_sendto+0x40/0x50 net/socket.c:1715
entry_SYSCALL_64_fastpath+0x29/0xa0
RIP: 0033:0x452f19
RSP: 002b:00007f071450ec58 EFLAGS: 00000212 ORIG_RAX: 000000000000002c
RAX: ffffffffffffffda RBX: 00007f071450f700 RCX: 0000000000452f19
RDX: 0000000000000166 RSI: 0000000020098000 RDI: 0000000000000013
RBP: 0000000000000000 R08: 0000000020cf9000 R09: 0000000000000010
R10: fffffffffffffffe R11: 0000000000000212 R12: 0000000000000000
R13: 0000000000a2f7cf R14: 00007f071450f9c0 R15: 0000000000000000
Code: 24 d1 00 00 00 49 8d 7c 24 38 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 38 89 da ec <5b> 0f b6 c0
41 5c 5d c3 e8 48 53 10 ff eb c2 e8 a1 53 10 ff eb
0-....: (125000 ticks this GP) idle=e96/140000000000001/0
softirq=1667512/1667512 fqs=31414
(t=125735 jiffies g=968435 c=968434 q=4498)
NMI backtrace for cpu 0
CPU: 0 PID: 8070 Comm: syz-executor6 Not tainted 4.15.0-rc9+ #210
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS
Google 01/01/2011
Call Trace:
<IRQ>
__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_single_cpu_backtrace include/linux/nmi.h:156 [inline]
rcu_dump_cpu_stacks+0x186/0x1d9 kernel/rcu/tree.c:1459
print_cpu_stall kernel/rcu/tree.c:1608 [inline]
check_cpu_stall.isra.61+0xbb8/0x15b0 kernel/rcu/tree.c:1676
__rcu_pending kernel/rcu/tree.c:3440 [inline]
rcu_pending kernel/rcu/tree.c:3502 [inline]
rcu_check_callbacks+0x256/0xd00 kernel/rcu/tree.c:2842
update_process_times+0x30/0x60 kernel/time/timer.c:1628
tick_sched_handle+0x85/0x160 kernel/time/tick-sched.c:162
tick_sched_timer+0x42/0x120 kernel/time/tick-sched.c:1194
__run_hrtimer kernel/time/hrtimer.c:1211 [inline]
__hrtimer_run_queues+0x358/0xe20 kernel/time/hrtimer.c:1275
hrtimer_interrupt+0x1c2/0x5e0 kernel/time/hrtimer.c:1309
local_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1025 [inline]
smp_apic_timer_interrupt+0x14a/0x700 arch/x86/kernel/apic/apic.c:1050
apic_timer_interrupt+0xa9/0xb0 arch/x86/entry/entry_64.S:937
</IRQ>
RIP: 0010:__sanitizer_cov_trace_pc+0x0/0x50
RSP: 0018:ffff8801af1c7828 EFLAGS: 00000246 ORIG_RAX: ffffffffffffff11
RAX: 0000000000000000 RBX: ffff8801c4b8bb00 RCX: ffffffff84acc87d
RDX: 0000000000000004 RSI: ffffc90003225000 RDI: ffff8801b4eb6b50
RBP: ffff8801af1c7868 R08: 0000000000000001 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000000 R12: ffff8801b4eb6a00
R13: dffffc0000000000 R14: ffffed003897177f R15: ffff8801c4b8bbfc
dst_confirm_neigh include/net/dst.h:419 [inline]
raw_sendmsg+0xece/0x23b0 net/ipv4/raw.c:702
inet_sendmsg+0x11f/0x5e0 net/ipv4/af_inet.c:764
sock_sendmsg_nosec net/socket.c:630 [inline]
sock_sendmsg+0xca/0x110 net/socket.c:640
SYSC_sendto+0x361/0x5c0 net/socket.c:1747
SyS_sendto+0x40/0x50 net/socket.c:1715
entry_SYSCALL_64_fastpath+0x29/0xa0
RIP: 0033:0x452f19
RSP: 002b:00007f071450ec58 EFLAGS: 00000212 ORIG_RAX: 000000000000002c
RAX: ffffffffffffffda RBX: 00007f071450f700 RCX: 0000000000452f19
RDX: 0000000000000166 RSI: 0000000020098000 RDI: 0000000000000013
RBP: 0000000000000000 R08: 0000000020cf9000 R09: 0000000000000010
R10: fffffffffffffffe R11: 0000000000000212 R12: 0000000000000000
R13: 0000000000a2f7cf R14: 00007f071450f9c0 R15: 0000000000000000


---
This bug is generated by a dumb bot. It may contain errors.
See https://goo.gl/tpsmEJ for details.
Direct all questions to syzk...@googlegroups.com.

syzbot will keep track of this bug report.
If you forgot to add the Reported-by tag, once the fix for this bug is
merged
into any tree, please reply to this email with:
#syz fix: exact-commit-title
To mark this as a duplicate of another syzbot report, please reply with:
#syz dup: exact-subject-of-another-report
If it's a one-off invalid bug report, please reply with:
#syz invalid
Note: if the crash happens again, it will cause creation of a new bug
report.
Note: all commands must start from beginning of the line in the email body.
To upstream this report, please reply with:
#syz upstream

[Dmitry Vyukov]

At the very least this has wrong CC list (which is fixed now). Also
this seems to have stopped happening, probably was introduced and
fixed on net-next.
#syz invalid

> --
> You received this message because you are subscribed to the Google Groups
> "syzkaller-upstream-moderation" group.
> To unsubscribe from this group and stop receiving emails from it, send an
> email to syzkaller-upstream-m...@googlegroups.com.
> To post to this group, send email to
> syzkaller-upst...@googlegroups.com.
> To view this discussion on the web visit
> https://groups.google.com/d/msgid/syzkaller-upstream-moderation/001a1144b0ca8a19b80563b4fde4%40google.com.
> For more options, visit https://groups.google.com/d/optout.