* [PATCH] hwmon: (nct6775) Fix potential Spectre v1
@ 2018-08-15 13:14 Gustavo A. R. Silva
2018-08-15 20:43 ` Guenter Roeck
0 siblings, 1 reply; 2+ messages in thread
From: Gustavo A. R. Silva @ 2018-08-15 13:14 UTC (permalink / raw)
To: Guenter Roeck, Jean Delvare
Cc: linux-hwmon, linux-kernel, Gustavo A. R. Silva
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(+)
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
^ permalink raw reply related [flat|nested] 2+ messages in thread
* Re: [PATCH] hwmon: (nct6775) Fix potential Spectre v1
2018-08-15 13:14 [PATCH] hwmon: (nct6775) Fix potential Spectre v1 Gustavo A. R. Silva
@ 2018-08-15 20:43 ` Guenter Roeck
0 siblings, 0 replies; 2+ messages in thread
From: Guenter Roeck @ 2018-08-15 20:43 UTC (permalink / raw)
To: Gustavo A. R. Silva; +Cc: Jean Delvare, linux-hwmon, linux-kernel
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
>
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