| Message ID | 20180815131437.GA25639@embeddedor.com (mailing list archive) |
|---|---|
| State | Accepted |
| Headers | show |
| Series | hwmon: (nct6775) Fix potential Spectre v1 | expand |
On Wed, Aug 15, 2018 at 08:14:37AM -0500, Gustavo A. R. Silva wrote: > val can be indirectly controlled by user-space, hence leading to > a potential exploitation of the Spectre variant 1 vulnerability. > > This issue was detected with the help of Smatch: > > vers/hwmon/nct6775.c:2698 store_pwm_weight_temp_sel() warn: potential > spectre issue 'data->temp_src' [r] > > Fix this by sanitizing val before using it to index data->temp_src > > Notice that given that speculation windows are large, the policy is > to kill the speculation on the first load and not worry if it can be > completed with a dependent load/store [1]. > > [1] https://marc.info/?l=linux-kernel&m=152449131114778&w=2 > > Cc: stable@vger.kernel.org > Signed-off-by: Gustavo A. R. Silva <gustavo@embeddedor.com> Applied. Thanks, Guenter > --- > drivers/hwmon/nct6775.c | 2 ++ > 1 file changed, 2 insertions(+) > > diff --git a/drivers/hwmon/nct6775.c b/drivers/hwmon/nct6775.c > index c6bd61e..944f5b6 100644 > --- a/drivers/hwmon/nct6775.c > +++ b/drivers/hwmon/nct6775.c > @@ -63,6 +63,7 @@ > #include <linux/bitops.h> > #include <linux/dmi.h> > #include <linux/io.h> > +#include <linux/nospec.h> > #include "lm75.h" > > #define USE_ALTERNATE > @@ -2689,6 +2690,7 @@ store_pwm_weight_temp_sel(struct device *dev, struct device_attribute *attr, > return err; > if (val > NUM_TEMP) > return -EINVAL; > + val = array_index_nospec(val, NUM_TEMP + 1); > if (val && (!(data->have_temp & BIT(val - 1)) || > !data->temp_src[val - 1])) > return -EINVAL; > -- > 2.7.4 >
diff --git a/drivers/hwmon/nct6775.c b/drivers/hwmon/nct6775.c index c6bd61e..944f5b6 100644 --- a/drivers/hwmon/nct6775.c +++ b/drivers/hwmon/nct6775.c @@ -63,6 +63,7 @@ #include <linux/bitops.h> #include <linux/dmi.h> #include <linux/io.h> +#include <linux/nospec.h> #include "lm75.h" #define USE_ALTERNATE @@ -2689,6 +2690,7 @@ store_pwm_weight_temp_sel(struct device *dev, struct device_attribute *attr, return err; if (val > NUM_TEMP) return -EINVAL; + val = array_index_nospec(val, NUM_TEMP + 1); if (val && (!(data->have_temp & BIT(val - 1)) || !data->temp_src[val - 1])) return -EINVAL;
val can be indirectly controlled by user-space, hence leading to a potential exploitation of the Spectre variant 1 vulnerability. This issue was detected with the help of Smatch: vers/hwmon/nct6775.c:2698 store_pwm_weight_temp_sel() warn: potential spectre issue 'data->temp_src' [r] Fix this by sanitizing val before using it to index data->temp_src Notice that given that speculation windows are large, the policy is to kill the speculation on the first load and not worry if it can be completed with a dependent load/store [1]. [1] https://marc.info/?l=linux-kernel&m=152449131114778&w=2 Cc: stable@vger.kernel.org Signed-off-by: Gustavo A. R. Silva <gustavo@embeddedor.com> --- drivers/hwmon/nct6775.c | 2 ++ 1 file changed, 2 insertions(+)