WARNING in task_participate_group

[upstream] WARNING in task_participate_group_stop (2)
Status: upstream: reported C repro on 2018/04/29 17:00
Reported-by: syzbot+b109633ea805cac54a61@syzkaller.appspotmail.com
First: 204d, last: 43d

similar bugs:
Kernel	Title	Repro	Count	Last	Reported	Patched	Status
upstream	WARNING in task_participate_group_stop	C	29	370d	385d	4/12	fixed on 2018/02/02 04:39

Sample crash report:

random: sshd: uninitialized urandom read (32 bytes read)
random: sshd: uninitialized urandom read (32 bytes read)
random: sshd: uninitialized urandom read (32 bytes read)
WARNING: CPU: 1 PID: 4520 at kernel/signal.c:351 task_participate_group_stop+0x205/0x260 kernel/signal.c:351
Kernel panic - not syncing: panic_on_warn set ...

CPU: 1 PID: 4520 Comm: 3 Not tainted 4.17.0-rc2+ #22
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+0x1b9/0x294 lib/dump_stack.c:113
 panic+0x22f/0x4de kernel/panic.c:184
 __warn.cold.8+0x163/0x1b3 kernel/panic.c:536
 report_bug+0x252/0x2d0 lib/bug.c:186
 fixup_bug arch/x86/kernel/traps.c:178 [inline]
 do_error_trap+0x1de/0x490 arch/x86/kernel/traps.c:296
 do_invalid_op+0x1b/0x20 arch/x86/kernel/traps.c:315
 invalid_op+0x14/0x20 arch/x86/entry/entry_64.S:992
RIP: 0010:task_participate_group_stop+0x205/0x260 kernel/signal.c:351
RSP: 0018:ffff8801ae7b7880 EFLAGS: 00010093
RAX: ffff8801d96200c0 RBX: 0000000000000000 RCX: ffffffff81498b5b
RDX: 0000000000000000 RSI: ffffffff81498c75 RDI: 0000000000000005
RBP: ffff8801ae7b78a0 R08: ffff8801d96200c0 R09: ffffed0036c48971
R10: ffffed0036c48971 R11: ffff8801b6244b8b R12: ffff8801d926ecd8
R13: ffff8801d926ec40 R14: 0000000000040000 R15: dffffc0000000000
 do_signal_stop+0x502/0xa20 kernel/signal.c:2176
 get_signal+0x9b4/0x1960 kernel/signal.c:2353
 do_signal+0x98/0x2040 arch/x86/kernel/signal.c:810
 exit_to_usermode_loop+0x28a/0x310 arch/x86/entry/common.c:162
 prepare_exit_to_usermode arch/x86/entry/common.c:196 [inline]
 syscall_return_slowpath arch/x86/entry/common.c:265 [inline]
 do_syscall_64+0x6ac/0x800 arch/x86/entry/common.c:290
 entry_SYSCALL_64_after_hwframe+0x49/0xbe
RIP: 0033:0x127
RSP: 002b:00007ffda970b440 EFLAGS: 00000200 ORIG_RAX: 000000000000003b
RAX: 0000000000000000 RBX: 0000000000000000 RCX: 0000000000000000
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000000
RBP: 0000000000000000 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000000 R12: 0000000000000000
R13: 0000000000000000 R14: 0000000000000000 R15: 0000000000000000
Dumping ftrace buffer:
   (ftrace buffer empty)
Kernel Offset: disabled
Rebooting in 86400 seconds..

All crashes (4):
Manager	Time	Kernel	Commit	Syzkaller	Config	Log	Report	Syz repro	C repro	Maintainers
ci-upstream-kasan-gce-root	2018/04/29 02:26	upstream	bf8f5de1	d5a5d045	.config	log	report	syz	C	akpm@linux-foundation.org, ebiederm@xmission.com, ldv@altlinux.org, linux-kernel@vger.kernel.org, linux@dominikbrodowski.net, oleg@redhat.com, viro@zeniv.linux.org.uk
ci-upstream-kasan-gce	2018/04/28 22:08	upstream	a97d8efd	d5a5d045	.config	log	report	syz	C	akpm@linux-foundation.org, ebiederm@xmission.com, ldv@altlinux.org, linux-kernel@vger.kernel.org, linux@dominikbrodowski.net, oleg@redhat.com, viro@zeniv.linux.org.uk
ci-upstream-kasan-gce-386	2018/05/02 13:48	upstream	f2125992	d5b114b4	.config	log	report	syz		akpm@linux-foundation.org, ebiederm@xmission.com, ldv@altlinux.org, linux-kernel@vger.kernel.org, linux@dominikbrodowski.net, oleg@redhat.com, viro@zeniv.linux.org.uk
ci-upstream-kasan-gce-selinux-root	2018/10/07 07:37	upstream	c1d84a1b	8b311eaf	.config	log	report			akpm@linux-foundation.org, anna-maria@linutronix.de, christian@brauner.io, ebiederm@xmission.com, linux-kernel@vger.kernel.org, oleg@redhat.com