KCSAN: data-race in ktime_get_real_seconds / timekeeping_inject

KCSAN: data-race in ktime_get_real_seconds / timekeeping_inject_offset (2)
Status: moderation: reported on 2020/12/07 11:41
Reported-by: syzbot+eb0bb2eb0097bddc9fea@syzkaller.appspotmail.com
First crash: 138d, last: 15d

similar bugs (1):
Kernel	Title	Repro	Cause bisect	Fix bisect	Count	Last	Reported	Patched	Status
upstream	KCSAN: data-race in ktime_get_real_seconds / timekeeping_inject_offset				3	189d	214d	0/17	auto-closed as invalid on 2020/08/23 09:27

Sample crash report:

==================================================================
BUG: KCSAN: data-race in ktime_get_real_seconds / timekeeping_inject_offset

read-write to 0xffffffff883024f8 of 8 bytes by task 5219 on cpu 0:
 tk_xtime_add kernel/time/timekeeping.c:144 [inline]
 timekeeping_inject_offset+0x468/0x6a0 kernel/time/timekeeping.c:1365
 do_adjtimex+0x569/0x660 kernel/time/timekeeping.c:2396
 posix_clock_realtime_adj+0x11/0x20 kernel/time/posix-timers.c:191
 do_clock_adjtime kernel/time/posix-timers.c:1109 [inline]
 __do_sys_clock_adjtime kernel/time/posix-timers.c:1121 [inline]
 __se_sys_clock_adjtime kernel/time/posix-timers.c:1112 [inline]
 __x64_sys_clock_adjtime+0x12c/0x1b0 kernel/time/posix-timers.c:1112
 do_syscall_64+0x39/0x80 arch/x86/entry/common.c:46
 entry_SYSCALL_64_after_hwframe+0x44/0xa9

read to 0xffffffff883024f8 of 8 bytes by task 5216 on cpu 1:
 ktime_get_real_seconds+0x11/0x20 kernel/time/timekeeping.c:1009
 recently_deleted fs/ext4/ialloc.c:703 [inline]
 find_inode_bit+0x231/0x3a0 fs/ext4/ialloc.c:728
 __ext4_new_inode+0xd22/0x3060 fs/ext4/ialloc.c:1062
 ext4_symlink+0x2bc/0x780 fs/ext4/namei.c:3330
 vfs_symlink+0x216/0x2d0 fs/namei.c:3962
 do_symlinkat+0xee/0x280 fs/namei.c:3989
 __do_sys_symlink fs/namei.c:4008 [inline]
 __se_sys_symlink fs/namei.c:4006 [inline]
 __x64_sys_symlink+0x32/0x40 fs/namei.c:4006
 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: 5216 Comm: syz-executor.5 Not tainted 5.11.0-rc2-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
==================================================================

Crashes (11):
Manager	Time	Kernel	Commit	Syzkaller	Config	Log	Report	VM info	Maintainers
ci2-upstream-kcsan-gce	2021/01/10 02:55	upstream	2ff90100	2c1f2513	.config	log	report	info	john.stultz@linaro.org, linux-kernel@vger.kernel.org, sboyd@kernel.org, tglx@linutronix.de
ci2-upstream-kcsan-gce	2020/12/24 12:08	upstream	58cf05f5	c2c1d1dd	.config	log	report	info	john.stultz@linaro.org, linux-kernel@vger.kernel.org, sboyd@kernel.org, tglx@linutronix.de
ci2-upstream-kcsan-gce	2020/12/22 02:49	upstream	8653b778	04201c06	.config	log	report	info	john.stultz@linaro.org, linux-kernel@vger.kernel.org, sboyd@kernel.org, tglx@linutronix.de
ci2-upstream-kcsan-gce	2020/12/19 05:44	upstream	3644e2d2	04201c06	.config	log	report	info	john.stultz@linaro.org, linux-kernel@vger.kernel.org, sboyd@kernel.org, tglx@linutronix.de
ci2-upstream-kcsan-gce	2020/11/19 17:12	upstream	c2e7554e	0767f13f	.config	log	report	info	john.stultz@linaro.org, linux-kernel@vger.kernel.org, sboyd@kernel.org, tglx@linutronix.de
ci2-upstream-kcsan-gce	2020/11/02 18:26	upstream	3cea11cd	8bc4594f	.config	log	report	info	john.stultz@linaro.org, linux-kernel@vger.kernel.org, sboyd@kernel.org, tglx@linutronix.de
ci2-upstream-kcsan-gce	2020/10/29 11:16	upstream	23859ae4	f24824d3	.config	log	report	info	john.stultz@linaro.org, linux-kernel@vger.kernel.org, sboyd@kernel.org, tglx@linutronix.de
ci2-upstream-kcsan-gce	2020/10/24 11:03	upstream	f11901ed	2bb6666c	.config	log	report	info	john.stultz@linaro.org, linux-kernel@vger.kernel.org, sboyd@kernel.org, tglx@linutronix.de
ci2-upstream-kcsan-gce	2020/09/23 20:23	upstream	805c6d3c	54289b08	.config	log	report	info	john.stultz@linaro.org, linux-kernel@vger.kernel.org, sboyd@kernel.org, tglx@linutronix.de
ci2-upstream-kcsan-gce	2020/09/09 18:59	upstream	34d4ddd3	ac7ca78e	.config	log	report		john.stultz@linaro.org, linux-kernel@vger.kernel.org, sboyd@kernel.org, tglx@linutronix.de
ci2-upstream-kcsan-gce	2020/09/09 03:08	upstream	6f6a73c8	abf9ba4f	.config	log	report		john.stultz@linaro.org, linux-kernel@vger.kernel.org, sboyd@kernel.org, tglx@linutronix.de