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@xxxxxxxxxxxxxxx Signed-off-by: Gustavo A. R. Silva <gustavo@xxxxxxxxxxxxxx> --- 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
