hwmon: (nct6775) Fix potential Spectre v1
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> Signed-off-by: Guenter Roeck <linux@roeck-us.net>
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@ -63,6 +63,7 @@
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#include <linux/bitops.h>
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#include <linux/bitops.h>
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#include <linux/dmi.h>
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#include <linux/dmi.h>
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#include <linux/io.h>
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#include <linux/io.h>
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#include <linux/nospec.h>
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#include "lm75.h"
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#include "lm75.h"
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#define USE_ALTERNATE
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#define USE_ALTERNATE
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@ -2689,6 +2690,7 @@ store_pwm_weight_temp_sel(struct device *dev, struct device_attribute *attr,
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return err;
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return err;
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if (val > NUM_TEMP)
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if (val > NUM_TEMP)
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return -EINVAL;
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return -EINVAL;
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val = array_index_nospec(val, NUM_TEMP + 1);
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if (val && (!(data->have_temp & BIT(val - 1)) ||
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if (val && (!(data->have_temp & BIT(val - 1)) ||
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!data->temp_src[val - 1]))
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!data->temp_src[val - 1]))
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return -EINVAL;
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return -EINVAL;
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