[Xen-devel] [PATCH 5/9] cpufreq: avoid integer overflows.

[Tim Deegan <tim@xxxxxxx>]

The def_sampling_rate() one is, I think, a real bug.  The others were
spotted at the same time and are probably not bugs until we start
dealing with 40GHz CPus.

Coverity CID 1055682
Coverity CID 1055683

Signed-off-by: Tim Deegan <tim@xxxxxxx>
Cc: Jan Beulich <jbeulich@xxxxxxxx>
Cc: Liu Jinsong <jinsong.liu@xxxxxxxxx>
---
 xen/drivers/cpufreq/cpufreq_ondemand.c |    7 ++++---
 1 file changed, 4 insertions(+), 3 deletions(-)

diff --git a/xen/drivers/cpufreq/cpufreq_ondemand.c 
b/xen/drivers/cpufreq/cpufreq_ondemand.c
index b3f9ab8..7fdba03 100644
--- a/xen/drivers/cpufreq/cpufreq_ondemand.c
+++ b/xen/drivers/cpufreq/cpufreq_ondemand.c
@@ -144,7 +144,7 @@ static void dbs_check_cpu(struct cpu_dbs_info_s 
*this_dbs_info)
     }
 
     /* Check for frequency increase */
-    if (max_load_freq > dbs_tuners_ins.up_threshold * policy->cur) {
+    if (max_load_freq > (uint64_t) dbs_tuners_ins.up_threshold * policy->cur) {
         /* if we are already at full speed then break out early */
         if (policy->cur == max)
             return;
@@ -162,7 +162,8 @@ static void dbs_check_cpu(struct cpu_dbs_info_s 
*this_dbs_info)
      * can support the current CPU usage without triggering the up
      * policy. To be safe, we focus 10 points under the threshold.
      */
-    if (max_load_freq < (dbs_tuners_ins.up_threshold - 10) * policy->cur) {
+    if (max_load_freq
+        < (uint64_t) (dbs_tuners_ins.up_threshold - 10) * policy->cur) {
         uint64_t freq_next;
 
         freq_next = max_load_freq / (dbs_tuners_ins.up_threshold - 10);
@@ -246,7 +247,7 @@ int cpufreq_governor_dbs(struct cpufreq_policy *policy, 
unsigned int event)
          * is used for first time
          */
         if ((dbs_enable == 1) && !dbs_tuners_ins.sampling_rate) {
-            def_sampling_rate = policy->cpuinfo.transition_latency *
+            def_sampling_rate = (uint64_t) policy->cpuinfo.transition_latency *
                 DEF_SAMPLING_RATE_LATENCY_MULTIPLIER;
 
             if (def_sampling_rate < MIN_STAT_SAMPLING_RATE)
-- 
1.7.10.4


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