From: Mel Gorman mgorman@techsingularity.net
[ Upstream commit 703066188f63d66cc6b9d678e5b5ef1213c5938e ]
This patch null-terminates the temporary buffer in sched_scaling_write() so kstrtouint() does not return failure and checks the value is valid.
Before: $ cat /sys/kernel/debug/sched/tunable_scaling 1 $ echo 0 > /sys/kernel/debug/sched/tunable_scaling -bash: echo: write error: Invalid argument $ cat /sys/kernel/debug/sched/tunable_scaling 1
After: $ cat /sys/kernel/debug/sched/tunable_scaling 1 $ echo 0 > /sys/kernel/debug/sched/tunable_scaling $ cat /sys/kernel/debug/sched/tunable_scaling 0 $ echo 3 > /sys/kernel/debug/sched/tunable_scaling -bash: echo: write error: Invalid argument
Fixes: 8a99b6833c88 ("sched: Move SCHED_DEBUG sysctl to debugfs") Signed-off-by: Mel Gorman mgorman@techsingularity.net Signed-off-by: Peter Zijlstra (Intel) peterz@infradead.org Acked-by: Vincent Guittot vincent.guittot@linaro.org Link: https://lore.kernel.org/r/20210927114635.GH3959@techsingularity.net Signed-off-by: Sasha Levin sashal@kernel.org --- kernel/sched/debug.c | 8 +++++++- 1 file changed, 7 insertions(+), 1 deletion(-)
diff --git a/kernel/sched/debug.c b/kernel/sched/debug.c index 7e08e3d947c2..2c879cd02a5f 100644 --- a/kernel/sched/debug.c +++ b/kernel/sched/debug.c @@ -173,16 +173,22 @@ static ssize_t sched_scaling_write(struct file *filp, const char __user *ubuf, size_t cnt, loff_t *ppos) { char buf[16]; + unsigned int scaling;
if (cnt > 15) cnt = 15;
if (copy_from_user(&buf, ubuf, cnt)) return -EFAULT; + buf[cnt] = '\0';
- if (kstrtouint(buf, 10, &sysctl_sched_tunable_scaling)) + if (kstrtouint(buf, 10, &scaling)) return -EINVAL;
+ if (scaling >= SCHED_TUNABLESCALING_END) + return -EINVAL; + + sysctl_sched_tunable_scaling = scaling; if (sched_update_scaling()) return -EINVAL;