Messages in this thread | | | From | "Rafael J. Wysocki" <> | Subject | Re: [PATCH] cpufreq: intel_pstate: fix possible integer overflow | Date | Tue, 22 Oct 2013 00:47:18 +0200 |
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On Monday, October 21, 2013 08:56:22 AM Dirk Brandewie wrote: > On 10/19/2013 08:31 PM, Geyslan G. Bem wrote: > > The expression 'pstate << 8' is evaluated using 32-bit arithmetic while > > 'val' expects an expression of type u64. > > > > Signed-off-by: Geyslan G. Bem <geyslan@gmail.com> > Acked-by: Dirk Brandewie <dirk.j.brandewie@intel.com>
Actually, isn't (pstate << 8) guaranteed not to overflow?
> > --- > > drivers/cpufreq/intel_pstate.c | 2 +- > > 1 file changed, 1 insertion(+), 1 deletion(-) > > > > diff --git a/drivers/cpufreq/intel_pstate.c b/drivers/cpufreq/intel_pstate.c > > index badf620..43446b5 100644 > > --- a/drivers/cpufreq/intel_pstate.c > > +++ b/drivers/cpufreq/intel_pstate.c > > @@ -395,7 +395,7 @@ static void intel_pstate_set_pstate(struct cpudata *cpu, int pstate) > > trace_cpu_frequency(pstate * 100000, cpu->cpu); > > > > cpu->pstate.current_pstate = pstate; > > - val = pstate << 8; > > + val = (u64)pstate << 8; > > if (limits.no_turbo) > > val |= (u64)1 << 32; > > > > > -- I speak only for myself. Rafael J. Wysocki, Intel Open Source Technology Center.
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