[PATCH 12/18] Thermal/int340x: prevent bounds-check bypass via speculative execution

Dan Williams
2018-01-06T01:10:59Z

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
@@ -17,6 +17,7 @@
#include <linux/init.h>
#include <linux/acpi.h>
#include <linux/thermal.h>
+#include <linux/compiler.h>
#include "int340x_thermal_zone.h"

static int int340x_thermal_get_zone_temp(struct thermal_zone_device *zone,
@@ -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))) {
+ *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) {