linux-kernel - [PATCH 3.16 058/346] posix_cpu_timer: Exit early when process has been reaped

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Message-ID: <lsq.1479082460.722898881@decadent.org.uk>
Date:   Mon, 14 Nov 2016 00:14:20 +0000
From:   Ben Hutchings <ben@...adent.org.uk>
To:     linux-kernel@...r.kernel.org, stable@...r.kernel.org
CC:     akpm@...ux-foundation.org, "Thomas Gleixner" <tglx@...utronix.de>,
        "Alexey Dobriyan" <adobriyan@...il.com>
Subject: [PATCH 3.16 058/346] posix_cpu_timer: Exit early when process has
 been reaped

3.16.39-rc1 review patch.  If anyone has any objections, please let me know.

------------------

From: Alexey Dobriyan <adobriyan@...il.com>

commit 2c13ce8f6b2f6fd9ba2f9261b1939fc0f62d1307 upstream.

Variable "now" seems to be genuinely used unintialized
if branch

	if (CPUCLOCK_PERTHREAD(timer->it_clock)) {

is not taken and branch

	if (unlikely(sighand == NULL)) {

is taken. In this case the process has been reaped and the timer is marked as
disarmed anyway. So none of the postprocessing of the sample is
required. Return right away.

Signed-off-by: Alexey Dobriyan <adobriyan@...il.com>
Link: http://lkml.kernel.org/r/20160707223911.GA26483@p183.telecom.by
Signed-off-by: Thomas Gleixner <tglx@...utronix.de>
[bwh: Backported to 3.16: adjust filename]
Signed-off-by: Ben Hutchings <ben@...adent.org.uk>
---
 kernel/posix-cpu-timers.c | 1 +
 1 file changed, 1 insertion(+)

--- a/kernel/posix-cpu-timers.c
+++ b/kernel/posix-cpu-timers.c
@@ -798,6 +798,7 @@ static void posix_cpu_timer_get(struct k
 			timer->it.cpu.expires = 0;
 			sample_to_timespec(timer->it_clock, timer->it.cpu.expires,
 					   &itp->it_value);
+			return;
 		} else {
 			cpu_timer_sample_group(timer->it_clock, p, &now);
 			unlock_task_sighand(p, &flags);