[PATCH 4.4 32/41] timer/sysclt: Restrict timer migration sysctl values to 0 and 1

From: Greg Kroah-Hartman
Date: Tue Oct 03 2017 - 09:12:07 EST


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

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

From: Myungho Jung <mhjungk@xxxxxxxxx>

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@xxxxxxxxx>
Link: http://lkml.kernel.org/r/1492640690-3550-1-git-send-email-mhjungk@xxxxxxxxx
Signed-off-by: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Cc: Kazuhiro Hayashi <kazuhiro3.hayashi@xxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>

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

--- a/kernel/sysctl.c
+++ b/kernel/sysctl.c
@@ -1159,6 +1159,8 @@ 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
@@ -127,7 +127,7 @@ 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);