linux-kernel - [PATCH 4.9 58/64] timer/sysclt: Restrict timer migration sysctl values to 0 and 1

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Date:   Tue,  3 Oct 2017 14:23:50 +0200
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, Myungho Jung <mhjungk@...il.com>,
        Thomas Gleixner <tglx@...utronix.de>,
        Kazuhiro Hayashi <kazuhiro3.hayashi@...hiba.co.jp>
Subject: [PATCH 4.9 58/64] timer/sysclt: Restrict timer migration sysctl values to 0 and 1

4.9-stable review patch.  If anyone has any objections, please let me know.

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

From: Myungho Jung <mhjungk@...il.com>

commit b94bf594cf8ed67cdd0439e70fa939783471597a upstream.

timer_migration sysctl acts as a boolean switch, so the allowed values
should be restricted to 0 and 1.

Add the necessary extra fields to the sysctl table entry to enforce that.

[ tglx: Rewrote changelog ]

Signed-off-by: Myungho Jung <mhjungk@...il.com>
Link: http://lkml.kernel.org/r/1492640690-3550-1-git-send-email-mhjungk@gmail.com
Signed-off-by: Thomas Gleixner <tglx@...utronix.de>
Cc: Kazuhiro Hayashi <kazuhiro3.hayashi@...hiba.co.jp>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>

---
 kernel/sysctl.c     |    2 ++
 kernel/time/timer.c |    2 +-
 2 files changed, 3 insertions(+), 1 deletion(-)

--- a/kernel/sysctl.c
+++ b/kernel/sysctl.c
@@ -1189,6 +1189,8 @@ static struct ctl_table kern_table[] = {
 		.maxlen		= sizeof(unsigned int),
 		.mode		= 0644,
 		.proc_handler	= timer_migration_handler,
+		.extra1		= &zero,
+		.extra2		= &one,
 	},
 #endif
 #ifdef CONFIG_BPF_SYSCALL
--- a/kernel/time/timer.c
+++ b/kernel/time/timer.c
@@ -240,7 +240,7 @@ int timer_migration_handler(struct ctl_t
 	int ret;
 
 	mutex_lock(&mutex);
-	ret = proc_dointvec(table, write, buffer, lenp, ppos);
+	ret = proc_dointvec_minmax(table, write, buffer, lenp, ppos);
 	if (!ret && write)
 		timers_update_migration(false);
 	mutex_unlock(&mutex);