KCSAN: data-race in exit_signals / get_task

KCSAN: data-race in exit_signals / get_task_mm
Status: closed as invalid on 2020/06/18 14:13
Reported-by: syzbot+@syzkaller.appspotmail.com
First crash: 471d, last: 471d

similar bugs (5):
Kernel	Title	Count	Last	Reported	Patched	Status
upstream	KCSAN: data-race in exit_signals / get_task_mm (4)	1	265d	265d	0/22	auto-closed as invalid on 2021/02/05 09:18
upstream	KCSAN: data-race in exit_signals / get_task_mm (3)	3	317d	290d	0/22	auto-closed as invalid on 2020/12/21 11:47
upstream	KCSAN: data-race in exit_signals / get_task_mm (5)	1	228d	228d	0/22	auto-closed as invalid on 2021/03/14 19:17
upstream	KCSAN: data-race in exit_signals / get_task_mm (6)	1	122d	122d	0/22	auto-closed as invalid on 2021/06/28 13:19
upstream	KCSAN: data-race in exit_signals / get_task_mm (2)	2	416d	419d	0/22	auto-closed as invalid on 2020/09/07 01:28

Sample crash report:

==================================================================
BUG: KCSAN: data-race in exit_signals / get_task_mm

write to 0xffff8880a7c950a4 of 4 bytes by task 20593 on cpu 0:
 exit_signals+0x135/0x4c0 kernel/signal.c:2827
 do_exit+0x17b/0x11e0 kernel/exit.c:744
 do_group_exit+0xae/0x1a0 kernel/exit.c:893
 __do_sys_exit_group kernel/exit.c:904 [inline]
 __se_sys_exit_group kernel/exit.c:902 [inline]
 __x64_sys_exit_group+0x2b/0x30 kernel/exit.c:902
 do_syscall_64+0xc7/0x3b0 arch/x86/entry/common.c:295
 entry_SYSCALL_64_after_hwframe+0x44/0xa9

read to 0xffff8880a7c950a4 of 4 bytes by task 20595 on cpu 1:
 get_task_mm+0x4b/0x90 kernel/fork.c:1215
 get_task_cmdline fs/proc/base.c:348 [inline]
 proc_pid_cmdline_read+0x98/0x700 fs/proc/base.c:368
 do_loop_readv_writev fs/read_write.c:715 [inline]
 do_loop_readv_writev fs/read_write.c:702 [inline]
 do_iter_read+0x33f/0x3a0 fs/read_write.c:936
 vfs_readv+0x9c/0xf0 fs/read_write.c:1054
 do_preadv+0x129/0x1c0 fs/read_write.c:1146
 __do_sys_preadv fs/read_write.c:1196 [inline]
 __se_sys_preadv fs/read_write.c:1191 [inline]
 __x64_sys_preadv+0x5e/0x80 fs/read_write.c:1191
 do_syscall_64+0xc7/0x3b0 arch/x86/entry/common.c:295
 entry_SYSCALL_64_after_hwframe+0x44/0xa9

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 PID: 20595 Comm: syz-executor.4 Not tainted 5.7.0-rc1-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
==================================================================

Crashes (1):
Manager	Time	Kernel	Commit	Syzkaller	Config	Log	Report	Syz repro	C repro	VM info	Title
ci2-upstream-kcsan-gce	2020/06/09 01:01	https://github.com/google/ktsan.git kcsan	7c3cd68e5d38	0d60b78a	.config	log	report