KCSAN: data-race in get_signal / ptrace_check

KCSAN: data-race in get_signal / ptrace_check_attach (2)
Status: moderation: reported on 2020/09/21 10:02
Reported-by: syzbot+670667eef68c9ab0c5fc@syzkaller.appspotmail.com
First crash: 254d, last: 14d

similar bugs (1):
Kernel	Title	Repro	Cause bisect	Fix bisect	Count	Last	Reported	Patched	Status
upstream	KCSAN: data-race in get_signal / ptrace_check_attach				23	260d	454d	0/21	closed as invalid on 2020/06/18 14:24

Sample crash report:

==================================================================
BUG: KCSAN: data-race in get_signal / ptrace_check_attach

write to 0xffff888026a5a500 of 8 bytes by task 15378 on cpu 0:
 ptrace_signal kernel/signal.c:2490 [inline]
 get_signal+0x7ef/0x14e0 kernel/signal.c:2669
 arch_do_signal_or_restart+0x2a/0x270 arch/x86/kernel/signal.c:811
 handle_signal_work kernel/entry/common.c:147 [inline]
 exit_to_user_mode_loop kernel/entry/common.c:171 [inline]
 exit_to_user_mode_prepare+0x11a/0x1b0 kernel/entry/common.c:201
 __syscall_exit_to_user_mode_work kernel/entry/common.c:283 [inline]
 syscall_exit_to_user_mode+0x20/0x40 kernel/entry/common.c:294
 do_syscall_64+0x45/0x80 arch/x86/entry/common.c:56
 entry_SYSCALL_64_after_hwframe+0x44/0xa9

read to 0xffff888026a5a500 of 8 bytes by task 15383 on cpu 1:
 ptrace_freeze_traced kernel/ptrace.c:178 [inline]
 ptrace_check_attach+0xdc/0x230 kernel/ptrace.c:247
 __do_sys_ptrace kernel/ptrace.c:1266 [inline]
 __se_sys_ptrace+0xdb/0x2e0 kernel/ptrace.c:1236
 __x64_sys_ptrace+0x51/0x60 kernel/ptrace.c:1236
 do_syscall_64+0x39/0x80 arch/x86/entry/common.c:46
 entry_SYSCALL_64_after_hwframe+0x44/0xa9

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 PID: 15383 Comm: syz-executor.1 Not tainted 5.11.0-rc7-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
==================================================================
Kernel panic - not syncing: panic_on_warn set ...
CPU: 1 PID: 15383 Comm: syz-executor.1 Not tainted 5.11.0-rc7-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Call Trace:
 __dump_stack lib/dump_stack.c:79 [inline]
 dump_stack+0x116/0x15d lib/dump_stack.c:120
 panic+0x1e7/0x5fa kernel/panic.c:231
 kcsan_report+0x67b/0x680 kernel/kcsan/report.c:634
 kcsan_setup_watchpoint+0x472/0x4d0 kernel/kcsan/core.c:568
 ptrace_freeze_traced kernel/ptrace.c:178 [inline]
 ptrace_check_attach+0xdc/0x230 kernel/ptrace.c:247
 __do_sys_ptrace kernel/ptrace.c:1266 [inline]
 __se_sys_ptrace+0xdb/0x2e0 kernel/ptrace.c:1236
 __x64_sys_ptrace+0x51/0x60 kernel/ptrace.c:1236
 do_syscall_64+0x39/0x80 arch/x86/entry/common.c:46
 entry_SYSCALL_64_after_hwframe+0x44/0xa9
RIP: 0033:0x465d99
Code: ff ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 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 73 01 c3 48 c7 c1 bc ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007f4595125188 EFLAGS: 00000246 ORIG_RAX: 0000000000000065
RAX: ffffffffffffffda RBX: 000000000056bf60 RCX: 0000000000465d99
RDX: 0000000000000000 RSI: 0000000000000211 RDI: 000000000000000d
RBP: 00000000004bcf27 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000020000080 R11: 0000000000000246 R12: 000000000056bf60
R13: 00007ffe94dabcdf R14: 00007f4595125300 R15: 0000000000022000
Shutting down cpus with NMI
Kernel Offset: disabled
Rebooting in 86400 seconds..

Crashes (116):
Manager	Time	Kernel	Commit	Syzkaller	Config	Log	Report	VM info	Title
ci2-upstream-kcsan-gce	2021/02/14 23:01	upstream	358fecee	98682e5e	.config	log	report	info	KCSAN: data-race in get_signal / ptrace_check_attach
ci2-upstream-kcsan-gce	2021/02/13 09:07	upstream	c6d8570e	98682e5e	.config	log	report	info	KCSAN: data-race in get_signal / ptrace_check_attach
ci2-upstream-kcsan-gce	2021/02/08 17:52	upstream	92bf2261	2ce644fc	.config	log	report	info	KCSAN: data-race in get_signal / ptrace_check_attach
ci2-upstream-kcsan-gce	2021/02/07 23:33	upstream	b75dba7f	2ce644fc	.config	log	report	info	KCSAN: data-race in get_signal / ptrace_check_attach
ci2-upstream-kcsan-gce	2021/02/05 08:23	upstream	5c279c4c	23a562df	.config	log	report	info	KCSAN: data-race in get_signal / ptrace_check_attach
ci2-upstream-kcsan-gce	2021/02/03 11:11	upstream	3aaf0a27	624dad51	.config	log	report	info	KCSAN: data-race in get_signal / ptrace_check_attach
ci2-upstream-kcsan-gce	2021/02/01 21:46	upstream	88bb507a	e6b95f32	.config	log	report	info	KCSAN: data-race in get_signal / ptrace_check_attach
ci2-upstream-kcsan-gce	2021/01/31 20:52	upstream	6642d600	fc9fd31e	.config	log	report	info	KCSAN: data-race in get_signal / ptrace_check_attach
ci2-upstream-kcsan-gce	2021/01/27 15:24	upstream	2ab38c17	a0ebf917	.config	log	report	info	KCSAN: data-race in get_signal / ptrace_check_attach
ci2-upstream-kcsan-gce	2021/01/26 04:52	upstream	f8ad8187	52e37319	.config	log	report	info	KCSAN: data-race in get_signal / ptrace_check_attach
ci2-upstream-kcsan-gce	2021/01/25 03:19	upstream	e6806137	52e37319	.config	log	report	info	KCSAN: data-race in get_signal / ptrace_check_attach
ci2-upstream-kcsan-gce	2021/01/22 16:17	upstream	83d09ad4	d4f4eca5	.config	log	report	info	KCSAN: data-race in get_signal / ptrace_check_attach
ci2-upstream-kcsan-gce	2021/01/20 20:24	upstream	45dfb8a5	d4f4eca5	.config	log	report	info	KCSAN: data-race in get_signal / ptrace_check_attach
ci2-upstream-kcsan-gce	2021/01/14 05:24	upstream	65f0d241	269d24e8	.config	log	report	info
ci2-upstream-kcsan-gce	2021/01/10 05:23	upstream	2ff90100	2c1f2513	.config	log	report	info
ci2-upstream-kcsan-gce	2021/01/09 10:40	upstream	996e435f	a6c52263	.config	log	report	info
ci2-upstream-kcsan-gce	2021/01/05 12:23	upstream	36bbbd0e	a0234d98	.config	log	report	info
ci2-upstream-kcsan-gce	2021/01/03 15:12	upstream	3516bd72	79264ae3	.config	log	report	info
ci2-upstream-kcsan-gce	2020/12/31 15:01	upstream	f6e1ea19	79264ae3	.config	log	report	info
ci2-upstream-kcsan-gce	2020/12/27 20:37	upstream	f838f8d2	2242f77f	.config	log	report	info
ci2-upstream-kcsan-gce	2020/12/27 10:58	upstream	f838f8d2	821e0b09	.config	log	report	info
ci2-upstream-kcsan-gce	2020/12/25 12:11	upstream	71c5f031	b982b3ea	.config	log	report	info
ci2-upstream-kcsan-gce	2020/12/20 05:24	upstream	467f8165	04201c06	.config	log	report	info
ci2-upstream-kcsan-gce	2020/12/17 10:51	upstream	accefff5	04201c06	.config	log	report	info
ci2-upstream-kcsan-gce	2020/12/13 07:44	upstream	7b1b868e	bca53db9	.config	log	report	info
ci2-upstream-kcsan-gce	2020/12/05 07:48	upstream	b3298500	0ef84591	.config	log	report	info
ci2-upstream-kcsan-gce	2020/12/03 08:05	upstream	3bb61aa6	8c9190ef	.config	log	report	info
ci2-upstream-kcsan-gce	2020/12/02 14:33	upstream	509a1542	eff43e99	.config	log	report	info
ci2-upstream-kcsan-gce	2020/12/02 04:21	upstream	509a1542	c42a35e9	.config	log	report	info
ci2-upstream-kcsan-gce	2020/11/28 13:03	upstream	c84e1efa	3c7136c0	.config	log	report	info
ci2-upstream-kcsan-gce	2020/11/25 02:41	upstream	80145ac2	e34b696c	.config	log	report	info
ci2-upstream-kcsan-gce	2020/11/23 21:08	upstream	418baf2c	878fb17a	.config	log	report	info
ci2-upstream-kcsan-gce	2020/11/21 16:40	upstream	27bba9c5	c7ec2d19	.config	log	report	info
ci2-upstream-kcsan-gce	2020/11/21 04:09	upstream	4d02da97	68068804	.config	log	report	info
ci2-upstream-kcsan-gce	2020/11/20 05:27	upstream	131ad0b6	0767f13f	.config	log	report	info
ci2-upstream-kcsan-gce	2020/11/14 17:52	upstream	f01c30de	1bf9a662	.config	log	report	info
ci2-upstream-kcsan-gce	2020/11/12 08:12	upstream	3d5e28bf	cca87986	.config	log	report	info
ci2-upstream-kcsan-gce	2020/11/09 11:18	upstream	f8394f23	cba33199	.config	log	report	info
ci2-upstream-kcsan-gce	2020/11/08 02:16	upstream	4429f14a	cba33199	.config	log	report	info
ci2-upstream-kcsan-gce	2020/11/06 09:30	upstream	521b619a	cba33199	.config	log	report	info
ci2-upstream-kcsan-gce	2020/11/03 03:03	upstream	495023e4	7f344fa6	.config	log	report	info
ci2-upstream-kcsan-gce	2020/10/31 17:32	upstream	5fc6b075	8bc4594f	.config	log	report	info
ci2-upstream-kcsan-gce	2020/10/29 23:14	upstream	23859ae4	a0c7169a	.config	log	report	info
ci2-upstream-kcsan-gce	2020/10/29 11:19	upstream	23859ae4	f24824d3	.config	log	report	info
ci2-upstream-kcsan-gce	2020/10/28 20:33	upstream	ed8780e3	f24824d3	.config	log	report	info
ci2-upstream-kcsan-gce	2020/10/27 19:00	upstream	4525c878	94942294	.config	log	report	info
ci2-upstream-kcsan-gce	2020/10/26 16:55	upstream	3650b228	a7aac492	.config	log	report	info
ci2-upstream-kcsan-gce	2020/10/25 19:50	upstream	986b9eac	a1839e81	.config	log	report	info
ci2-upstream-kcsan-gce	2020/09/20 20:44	upstream	bdcf11de	9564d2e9	.config	log	report	info
ci2-upstream-kcsan-gce	2020/09/20 05:49	upstream	325d0eab	53ce8104	.config	log	report	info
ci2-upstream-kcsan-gce	2020/06/19 04:15	upstream	5e857ce6	bc258b50	.config	log	report