linux-kernel - [PATCH] time: zero old_value in timer

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Date:   Mon, 12 Jun 2017 12:10:49 -0700
From:   Andrei Vagin <avagin@...nvz.org>
To:     Thomas Gleixner <tglx@...utronix.de>
Cc:     linux-kernel@...r.kernel.org, Andrei Vagin <avagin@...nvz.org>
Subject: [PATCH] time: zero old_value in timer_settime

Currently timer_settime() returns random data in old_value

timer_settime(10, 0, {it_interval={tv_sec=0, tv_nsec=0},
		      it_value={tv_sec=2147483, tv_nsec=647000000}}, NULL) = 0
...
timer_settime(10, 0, {it_interval={tv_sec=0, tv_nsec=0},
		      it_value={tv_sec=0, tv_nsec=0}},
                     {it_interval={tv_sec=-1861316067,
                                   tv_nsec=18446645490300239488},
                      it_value={tv_sec=-1852565060, tv_nsec=133}}) = 0

Fixes: eabdec043853 ("posix-timers: Zero settings value in common code")
Cc: Thomas Gleixner <tglx@...utronix.de>
Signed-off-by: Andrei Vagin <avagin@...nvz.org>
---
 kernel/time/posix-timers.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/kernel/time/posix-timers.c b/kernel/time/posix-timers.c
index 6e7a70b1..e684cbb 100644
--- a/kernel/time/posix-timers.c
+++ b/kernel/time/posix-timers.c
@@ -833,6 +833,9 @@ SYSCALL_DEFINE4(timer_settime, timer_t, timer_id, int, flags,
 	if (!timr)
 		return -EINVAL;
 
+	if (rtn)
+		memset(rtn, 0, sizeof(*rtn));
+
 	kc = timr->kclock;
 	if (WARN_ON_ONCE(!kc || !kc->timer_set))
 		error = -EINVAL;
-- 
2.9.4