linux-kernel - [PATCH] hrtimer: Fix incorrect tai offset calculation for non high-res timer systems

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [thread-next>] [day] [month] [year] [list]

Message-Id: <1423097126-10236-1-git-send-email-john.stultz@linaro.org>
Date:	Wed,  4 Feb 2015 16:45:26 -0800
From:	John Stultz <john.stultz@...aro.org>
To:	lkml <linux-kernel@...r.kernel.org>
Cc:	John Stultz <john.stultz@...aro.org>,
	Thomas Gleixner <tglx@...utronix.de>,
	Ingo Molnar <mingo@...nel.org>, stable <stable@...r.kernel.org>
Subject: [PATCH] hrtimer: Fix incorrect tai offset calculation for non high-res timer systems

For tip/timers/urgent

I noticed some CLOCK_TAI timer test failures on one of my
less-frequently used configurations. And after digging in I
found in 76f4108892d9 (Cleanup hrtimer accessors to the
timekepeing state), the hrtimer_get_softirq_time tai offset
calucation was incorrectly rewritten, as the tai offset we return
shold be from CLOCK_MONOTONIC, and not CLOCK_REALTIME.

This results in CLOCK_TAI timers expiring early on non-highres
capable machines.

This patch fixes the issue, calculating the tai time properly from
the monotonic base.

Cc: Thomas Gleixner <tglx@...utronix.de>
Cc: Ingo Molnar <mingo@...nel.org>
Cc: stable <stable@...r.kernel.org> # 3.17+
Signed-off-by: John Stultz <john.stultz@...aro.org>
---
 kernel/time/hrtimer.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/kernel/time/hrtimer.c b/kernel/time/hrtimer.c
index 37e50aa..d8c724c 100644
--- a/kernel/time/hrtimer.c
+++ b/kernel/time/hrtimer.c
@@ -122,7 +122,7 @@ static void hrtimer_get_softirq_time(struct hrtimer_cpu_base *base)
 	mono = ktime_get_update_offsets_tick(&off_real, &off_boot, &off_tai);
 	boot = ktime_add(mono, off_boot);
 	xtim = ktime_add(mono, off_real);
-	tai = ktime_add(xtim, off_tai);
+	tai = ktime_add(mono, off_tai);
 
 	base->clock_base[HRTIMER_BASE_REALTIME].softirq_time = xtim;
 	base->clock_base[HRTIMER_BASE_MONOTONIC].softirq_time = mono;
-- 
1.9.1

--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/