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drivers: adc: Prevent overflow in max1125x_read_sample

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Fix potential integer overflow caused by unsafe shift when computing
ADC mid-scale offset. Applies resolution bounds and uses unsigned
shift to avoid undefined behavior.

Fixes: CID 487740
Signed-off-by: Sudarsan N <sudarsansamy2002@gmail.com>
This commit is contained in:
Sudarsan N
2025-06-02 07:30:11 +00:00
committed by Benjamin Cabé
parent 1fbb4e87f2
commit 34f5f8d556
1 changed files with 9 additions and 1 deletions
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10
drivers/adc/adc_max1125x.c
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@@ -403,9 +403,17 @@ static int max1125x_read_sample(const struct device *dev)
* the available input range is limited to the minimum or maximum
* data value.
*/
if (config->resolution > 24 || config->resolution < 1) {
LOG_ERR("Unsupported ADC resolution: %u", config->resolution);
return -EINVAL;
}
is_positive = buffer_rx[(config->resolution / 8)] >> 7;
if (is_positive) {
*data->buffer++ = sys_get_be24(buffer_rx) - (1 << (config->resolution - 1));
/* Ensure left shift is done using unsigned literal to avoid overflow. */
*data->buffer++ = sys_get_be24(buffer_rx) - (1U << (config->resolution - 1));
} else {
*data->buffer++ = sys_get_be24(buffer_rx + 1);
}