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    SubjectRe: [PATCH 12/18] Thermal/int340x: prevent bounds-check bypass via speculative execution
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    Date
    On 1/6/2018 4:10 AM, Dan Williams wrote:

    > Static analysis reports that 'trip' may be a user controlled value that
    > is used as a data dependency to read '*temp' from the 'd->aux_trips'
    > array. In order to avoid potential leaks of kernel memory values, block
    > speculative execution of the instruction stream that could issue reads
    > based on an invalid value of '*temp'.
    >
    > Based on an original patch by Elena Reshetova.
    >
    > Cc: Srinivas Pandruvada <srinivas.pandruvada@linux.intel.com>
    > Cc: Zhang Rui <rui.zhang@intel.com>
    > Cc: Eduardo Valentin <edubezval@gmail.com>
    > Signed-off-by: Elena Reshetova <elena.reshetova@intel.com>
    > Signed-off-by: Dan Williams <dan.j.williams@intel.com>
    > ---
    > .../thermal/int340x_thermal/int340x_thermal_zone.c | 14 ++++++++------
    > 1 file changed, 8 insertions(+), 6 deletions(-)
    >
    > diff --git a/drivers/thermal/int340x_thermal/int340x_thermal_zone.c b/drivers/thermal/int340x_thermal/int340x_thermal_zone.c
    > index 145a5c53ff5c..442a1d9bf7ad 100644
    > --- a/drivers/thermal/int340x_thermal/int340x_thermal_zone.c
    > +++ b/drivers/thermal/int340x_thermal/int340x_thermal_zone.c
    [...]
    > @@ -52,20 +53,21 @@ static int int340x_thermal_get_trip_temp(struct thermal_zone_device *zone,
    > int trip, int *temp)
    > {
    > struct int34x_thermal_zone *d = zone->devdata;
    > + unsigned long *elem;
    > int i;
    >
    > 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)
    > - *temp = d->aux_trips[trip];
    > - else if (trip == d->crt_trip_id)
    > + if ((elem = nospec_array_ptr(d->aux_trips, trip, d->aux_trip_nr))) {

    And here...

    > + *temp = *elem;
    > + } 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) {

    MBR, Sergei

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