[PATCH 3.8-stable] sched/debug: Fix sd->*_idx limit range avoiding overflow

[Jonghwan Choi]

From: libin <huawei.libin@xxxxxxxxxx>

This patch looks like it should be in the 3.8-stable tree, should we apply
it?

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

From: "libin <huawei.libin@xxxxxxxxxx>"

commit fd9b86d37a600488dbd80fe60cca46b822bff1cd upstream

Commit 201c373e8e ("sched/debug: Limit sd->*_idx range on
sysctl") was an incomplete bug fix.

This patch fixes sd->*_idx limit range to [0 ~ CPU_LOAD_IDX_MAX-1]
avoiding array overflow caused by setting sd->*_idx to CPU_LOAD_IDX_MAX
on sysctl.

Signed-off-by: Libin <huawei.libin@xxxxxxxxxx>
Cc: <jiang.liu@xxxxxxxxxx>
Cc: <guohanjun@xxxxxxxxxx>
Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
Link: http://lkml.kernel.org/r/51626610.2040607@xxxxxxxxxx
Signed-off-by: Ingo Molnar <mingo@xxxxxxxxxx>
Signed-off-by: Jonghwan Choi <jhbird.choi@xxxxxxxxxxx>
---
 kernel/sched/core.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/kernel/sched/core.c b/kernel/sched/core.c
index 26058d0..112a32a 100644
--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -4948,7 +4948,7 @@ static void sd_free_ctl_entry(struct ctl_table **tablep)
 }
 
 static int min_load_idx = 0;
-static int max_load_idx = CPU_LOAD_IDX_MAX;
+static int max_load_idx = CPU_LOAD_IDX_MAX-1;
 
 static void
 set_table_entry(struct ctl_table *entry,
-- 
1.7.10.4

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