KCSAN: data-race in yama_relation_cleanup / yama_task

KCSAN: data-race in yama_relation_cleanup / yama_task_free (3)
Status: moderation: reported on 2020/12/07 12:03
Reported-by: syzbot+5f3dcb2d7c7b062f7bae@syzkaller.appspotmail.com
First crash: 61d, last: 19d

similar bugs (2):
Kernel	Title	Repro	Cause bisect	Fix bisect	Count	Last	Reported	Patched	Status
upstream	KCSAN: data-race in yama_relation_cleanup / yama_task_free (2)				1	106d	106d	0/17	auto-closed as invalid on 2020/11/14 15:11
upstream	KCSAN: data-race in yama_relation_cleanup / yama_task_free				4	178d	199d	0/17	auto-closed as invalid on 2020/09/04 02:18

Sample crash report:

==================================================================
BUG: KCSAN: data-race in yama_relation_cleanup / yama_task_free

write to 0xffff888060acec10 of 1 bytes by interrupt on cpu 0:
 yama_ptracer_del security/yama/yama_lsm.c:191 [inline]
 yama_task_free+0xc3/0x160 security/yama/yama_lsm.c:207
 security_task_free+0x3f/0xa0 security/security.c:1597
 __put_task_struct+0xc2/0x3a0 kernel/fork.c:736
 put_task_struct include/linux/sched/task.h:111 [inline]
 delayed_put_task_struct+0x4e/0x130 kernel/exit.c:173
 rcu_do_batch kernel/rcu/tree.c:2489 [inline]
 rcu_core+0x69b/0xb90 kernel/rcu/tree.c:2723
 rcu_core_si+0x9/0x10 kernel/rcu/tree.c:2736
 __do_softirq+0x13c/0x2c3 kernel/softirq.c:343
 asm_call_irq_on_stack+0xf/0x20
 __run_on_irqstack arch/x86/include/asm/irq_stack.h:26 [inline]
 run_on_irqstack_cond arch/x86/include/asm/irq_stack.h:77 [inline]
 do_softirq_own_stack+0x32/0x40 arch/x86/kernel/irq_64.c:77
 invoke_softirq kernel/softirq.c:226 [inline]
 __irq_exit_rcu+0xb4/0xc0 kernel/softirq.c:420
 sysvec_apic_timer_interrupt+0x74/0x90 arch/x86/kernel/apic/apic.c:1096
 asm_sysvec_apic_timer_interrupt+0x12/0x20 arch/x86/include/asm/idtentry.h:628
 native_restore_fl arch/x86/include/asm/irqflags.h:41 [inline]
 arch_local_irq_restore arch/x86/include/asm/irqflags.h:84 [inline]
 kcsan_setup_watchpoint+0x1fc/0x4e0 kernel/kcsan/core.c:591
 tomoyo_check_acl+0xad/0x200 security/tomoyo/domain.c:173
 tomoyo_path_permission security/tomoyo/file.c:586 [inline]
 tomoyo_path_perm+0x22f/0x330 security/tomoyo/file.c:838
 tomoyo_inode_getattr+0x18/0x20 security/tomoyo/tomoyo.c:123
 security_inode_getattr+0x7f/0xd0 security/security.c:1280
 vfs_getattr fs/stat.c:121 [inline]
 vfs_statx+0xf8/0x270 fs/stat.c:189
 vfs_fstatat fs/stat.c:207 [inline]
 vfs_lstat include/linux/fs.h:3122 [inline]
 __do_sys_newlstat fs/stat.c:362 [inline]
 __se_sys_newlstat+0x46/0x250 fs/stat.c:356
 __x64_sys_newlstat+0x2d/0x40 fs/stat.c:356
 do_syscall_64+0x39/0x80 arch/x86/entry/common.c:46
 entry_SYSCALL_64_after_hwframe+0x44/0xa9

read to 0xffff888060acec10 of 1 bytes by task 27843 on cpu 1:
 yama_relation_cleanup+0x69/0x150 security/yama/yama_lsm.c:122
 process_one_work+0x3e1/0x950 kernel/workqueue.c:2275
 worker_thread+0x635/0xb90 kernel/workqueue.c:2421
 kthread+0x1fd/0x220 kernel/kthread.c:292
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:296

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 PID: 27843 Comm: kworker/1:0 Not tainted 5.11.0-rc2-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Workqueue: events yama_relation_cleanup
==================================================================

Crashes (4):
Manager	Time	Kernel	Commit	Syzkaller	Config	Log	Report	VM info	Maintainers
ci2-upstream-kcsan-gce	2021/01/05 09:02	upstream	36bbbd0e	2a28ff1f	.config	log	report	info	jmorris@namei.org, keescook@chromium.org, linux-kernel@vger.kernel.org, linux-security-module@vger.kernel.org, serge@hallyn.com
ci2-upstream-kcsan-gce	2020/12/25 16:59	upstream	71c5f031	b982b3ea	.config	log	report	info	jmorris@namei.org, keescook@chromium.org, linux-kernel@vger.kernel.org, linux-security-module@vger.kernel.org, serge@hallyn.com
ci2-upstream-kcsan-gce	2020/12/10 10:50	upstream	a2f5ea9e	c090b4da	.config	log	report	info	jmorris@namei.org, keescook@chromium.org, linux-kernel@vger.kernel.org, linux-security-module@vger.kernel.org, serge@hallyn.com
ci2-upstream-kcsan-gce	2020/11/24 11:51	upstream	d5beb314	1ab681a4	.config	log	report	info	jmorris@namei.org, keescook@chromium.org, linux-kernel@vger.kernel.org, linux-security-module@vger.kernel.org, serge@hallyn.com