Commit b562d140 authored by Qais Yousef's avatar Qais Yousef Committed by Ingo Molnar

sched/uclamp: Reject negative values in cpu_uclamp_write()

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: 2480c093 ("sched/uclamp: Extend CPU's cgroup controller")
Signed-off-by: default avatarQais Yousef <qais.yousef@arm.com>
Signed-off-by: default avatarPeter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: default avatarIngo Molnar <mingo@kernel.org>
Link: https://lkml.kernel.org/r/20200114210947.14083-1-qais.yousef@arm.com
parent b396f523
...@@ -7264,7 +7264,7 @@ capacity_from_percent(char *buf) ...@@ -7264,7 +7264,7 @@ capacity_from_percent(char *buf)
&req.percent); &req.percent);
if (req.ret) if (req.ret)
return req; return req;
if (req.percent > UCLAMP_PERCENT_SCALE) { if ((u64)req.percent > UCLAMP_PERCENT_SCALE) {
req.ret = -ERANGE; req.ret = -ERANGE;
return req; return req;
} }
......
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