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sched/uclamp: Reject negative values in cpu_uclamp_write()

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commit b562d14064 upstream.

The check to ensure that the new written value into cpu.uclamp.{min,max}
is within range, [0:100], wasn't working because of the signed
comparison

 7301                 if (req.percent > UCLAMP_PERCENT_SCALE) {
 7302                         req.ret = -ERANGE;
 7303                         return req;
 7304                 }

	# echo -1 > cpu.uclamp.min
	# cat cpu.uclamp.min
	42949671.96

Cast req.percent into u64 to force the comparison to be unsigned and
work as intended in capacity_from_percent().

	# echo -1 > cpu.uclamp.min
	sh: write error: Numerical result out of range

Fixes: 2480c09313 ("sched/uclamp: Extend CPU's cgroup controller")
Signed-off-by: Qais Yousef <qais.yousef@arm.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Link: https://lkml.kernel.org/r/20200114210947.14083-1-qais.yousef@arm.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Qais Yousef 2020-01-14 21:09:47 +00:00 committed by Greg Kroah-Hartman
parent 115402ee80
commit 9f6f61c61a
1 changed files with 1 additions and 1 deletions
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2
kernel/sched/core.c
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@ -7250,7 +7250,7 @@ capacity_from_percent(char *buf)
&req.percent);
if (req.ret)
return req;
if (req.percent > UCLAMP_PERCENT_SCALE) {
if ((u64)req.percent > UCLAMP_PERCENT_SCALE) {
req.ret = -ERANGE;
return req;
}