------------[ cut here ]------------
!valid_signal(sig)
WARNING: kernel/signal.c:2174 at do_notify_parent+0xd18/0xe30 kernel/signal.c:2174, CPU#0: syz.0.0/5343
Modules linked in:
CPU: 0 UID: 0 PID: 5343 Comm: syz.0.0 Not tainted syzkaller #0 PREEMPT(full) 
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.3-debian-1.16.3-2 04/01/2014
RIP: 0010:do_notify_parent+0xd18/0xe30 kernel/signal.c:2174
Code: c6 05 10 76 90 0e 01 48 c7 c7 e0 3a cb 8b be a3 08 00 00 48 c7 c2 60 3c cb 8b e8 b3 91 17 00 e9 2e fa ff ff e8 99 67 3b 00 90 <0f> 0b 90 45 31 e4 e9 1c ff ff ff e8 88 67 3b 00 90 0f 0b 90 e9 db
RSP: 0018:ffffc9000381f920 EFLAGS: 00010093
RAX: ffffffff818a5dd7 RBX: dffffc0000000000 RCX: ffff8880360a8000
RDX: 0000000000000000 RSI: 0000000000000080 RDI: 0000000000000040
RBP: ffffc9000381fa70 R08: 0000000000000003 R09: 0000000000000004
R10: dffffc0000000000 R11: fffff52000703f40 R12: ffff88800048c150
R13: ffff8880360a8000 R14: 0000000000000080 R15: 1ffff92000703f2c
FS:  0000000000000000(0000) GS:ffff88808c87b000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000200000000840 CR3: 000000000e74a000 CR4: 0000000000352ef0
Call Trace:
 <TASK>
 exit_notify kernel/exit.c:758 [inline]
 do_exit+0x13f1/0x22c0 kernel/exit.c:988
 do_group_exit+0x21b/0x2d0 kernel/exit.c:1119
 get_signal+0x1284/0x1330 kernel/signal.c:3037
 arch_do_signal_or_restart+0xbc/0x840 arch/x86/kernel/signal.c:337
 __exit_to_user_mode_loop kernel/entry/common.c:64 [inline]
 exit_to_user_mode_loop kernel/entry/common.c:98 [inline]
 __exit_to_user_mode_prepare include/linux/irq-entry-common.h:207 [inline]
 irqentry_exit_to_user_mode_prepare include/linux/irq-entry-common.h:244 [inline]
 irqentry_exit_to_user_mode include/linux/irq-entry-common.h:315 [inline]
 irqentry_exit+0x289/0x760 kernel/entry/common.c:162
 exc_general_protection+0x16b/0x1f0 arch/x86/kernel/traps.c:914
 asm_exc_general_protection+0x26/0x30 arch/x86/include/asm/idtentry.h:612
RIP: 0033:0x7f88cdd9ce61
Code: Unable to access opcode bytes at 0x7f88cdd9ce37.
RSP: 002b:0000200000000800 EFLAGS: 00010217
RAX: 0000000000000000 RBX: 00007f88ce015fa0 RCX: 00007f88cdd9ce59
RDX: 0000200000000900 RSI: 0000200000000800 RDI: 0000000000800080
RBP: 00007f88cde32d6f R08: 00002000000009c0 R09: 00002000000009c0
R10: 0000200000000940 R11: 0000000000000202 R12: 0000000000000000
R13: 00007f88ce016038 R14: 00007f88ce015fa0 R15: 00007ffde9b8e8e8
 </TASK>