Thermal/int340x: prevent speculative execution

Since the trip value in function int340x_thermal_get_trip_temp()
seems to be controllable by userspace and later on
conditionally (upon bound check) used to resolve
d->aux_trips, insert an observable speculation
barrier before its usage. This should prevent
observable speculation on that branch and avoid
kernel memory leak.

Signed-off-by: Elena Reshetova <elena.reshetova@intel.com>
Orabug: 27340445
CVE: CVE-2017-5753

Signed-off-by: Chuck Anderson <chuck.anderson@oracle.com>
Conflicts:
        patch refers to arch/x86/include/asm/msr-index.h
        code base has arch/x86/include/uapi/asm/msr-index.h

Reviewed-by: John Haxby <john.haxby@oracle.com>
Signed-off-by: Kirtikar Kashyap <kirtikar.kashyap@oracle.com>

diff --git a/drivers/thermal/int340x_thermal/int340x_thermal_zone.c b/drivers/thermal/int340x_thermal/int340x_thermal_zone.c
index 1e25133d35e2cbe8e7476a382bd27433a5801b0c..505c3d2a7ab61e687067a9f6d13b1ceb16bcfadc 100644 (file)
--- a/drivers/thermal/int340x_thermal/int340x_thermal_zone.c
+++ b/drivers/thermal/int340x_thermal/int340x_thermal_zone.c
@@ -57,15 +57,16 @@ static int int340x_thermal_get_trip_temp(struct thermal_zone_device *zone,
        if (d->override_ops && d->override_ops->get_trip_temp)
                return d->override_ops->get_trip_temp(zone, trip, temp);
 
-       if (trip < d->aux_trip_nr)
+       if (trip < d->aux_trip_nr) {
+               osb();
                *temp = d->aux_trips[trip];
-       else if (trip == d->crt_trip_id)
+       } else if (trip == d->crt_trip_id) {
                *temp = d->crt_temp;
-       else if (trip == d->psv_trip_id)
+       } else if (trip == d->psv_trip_id) {
                *temp = d->psv_temp;
-       else if (trip == d->hot_trip_id)
+       } else if (trip == d->hot_trip_id) {
                *temp = d->hot_temp;
-       else {
+       } else {
                for (i = 0; i < INT340X_THERMAL_MAX_ACT_TRIP_COUNT; i++) {
                        if (d->act_trips[i].valid &&
                            d->act_trips[i].id == trip) {