[tip:perf/urgent] perf/core: Fix the perf_cpu_time_max_percent check

[tip-bot for Tan Xiaojun]

Commit-ID:  1572e45a924f254d9570093abde46430c3172e3d
Gitweb:     http://git.kernel.org/tip/1572e45a924f254d9570093abde46430c3172e3d
Author:     Tan Xiaojun <tanxiaojun@xxxxxxxxxx>
AuthorDate: Thu, 23 Feb 2017 14:04:39 +0800
Committer:  Ingo Molnar <mingo@xxxxxxxxxx>
CommitDate: Fri, 24 Feb 2017 08:56:33 +0100

perf/core: Fix the perf_cpu_time_max_percent check

Use "proc_dointvec_minmax" instead of "proc_dointvec" to check the input
value from user-space.

If not, we can set a big value and some vars will overflow like
"sysctl_perf_event_sample_rate" which will cause a lot of unexpected
problems.

Signed-off-by: Tan Xiaojun <tanxiaojun@xxxxxxxxxx>
Signed-off-by: Peter Zijlstra (Intel) <peterz@xxxxxxxxxxxxx>
Cc: <acme@xxxxxxxxxx>
Cc: <alexander.shishkin@xxxxxxxxxxxxxxx>
Cc: Alexander Shishkin <alexander.shishkin@xxxxxxxxxxxxxxx>
Cc: Arnaldo Carvalho de Melo <acme@xxxxxxxxxx>
Cc: Jiri Olsa <jolsa@xxxxxxxxxx>
Cc: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
Cc: Stephane Eranian <eranian@xxxxxxxxxx>
Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Cc: Vince Weaver <vincent.weaver@xxxxxxxxx>
Link: http://lkml.kernel.org/r/1487829879-56237-1-git-send-email-tanxiaojun@xxxxxxxxxx
Signed-off-by: Ingo Molnar <mingo@xxxxxxxxxx>
---
 kernel/events/core.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/kernel/events/core.c b/kernel/events/core.c
index d4e3f8d..c1c1cdf 100644
--- a/kernel/events/core.c
+++ b/kernel/events/core.c
@@ -455,7 +455,7 @@ int perf_cpu_time_max_percent_handler(struct ctl_table *table, int write,
 				void __user *buffer, size_t *lenp,
 				loff_t *ppos)
 {
-	int ret = proc_dointvec(table, write, buffer, lenp, ppos);
+	int ret = proc_dointvec_minmax(table, write, buffer, lenp, ppos);
 
 	if (ret || !write)
 		return ret;