From 9f6f61c61a84515d1533a0c71ab3159f39960236 Mon Sep 17 00:00:00 2001 From: Qais Yousef Date: Tue, 14 Jan 2020 21:09:47 +0000 Subject: [PATCH] sched/uclamp: Reject negative values in cpu_uclamp_write() commit b562d140649966d4daedd0483a8fe59ad3bb465a 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: 2480c093130f ("sched/uclamp: Extend CPU's cgroup controller") Signed-off-by: Qais Yousef Signed-off-by: Peter Zijlstra (Intel) Signed-off-by: Ingo Molnar Link: https://lkml.kernel.org/r/20200114210947.14083-1-qais.yousef@arm.com Signed-off-by: Greg Kroah-Hartman --- 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 00743684a549..dfaefb175ba0 100644 --- a/kernel/sched/core.c +++ b/kernel/sched/core.c @@ -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; }