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hwmon: (max6697) Fix underflow when writing limit attributes

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[ Upstream commit cbf7467828cd4ec7ceac7a8b5b5ddb2f69f07b0e ]

Using DIV_ROUND_CLOSEST() on an unbound value can result in underflows.
Indeed, module test scripts report:

temp1_max: Suspected underflow: [min=0, read 255000, written -9223372036854775808]
temp1_crit: Suspected underflow: [min=0, read 255000, written -9223372036854775808]

Fix by introducing an extra set of clamping.

Fixes: 5372d2d71c ("hwmon: Driver for Maxim MAX6697 and compatibles")
Reviewed-by: Tzung-Bi Shih <tzungbi@kernel.org>
Signed-off-by: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Sasha Levin <sashal@kernel.org>
This commit is contained in:
Guenter Roeck
2024-07-13 14:26:19 -07:00
committed by Greg Kroah-Hartman
parent 6afaf55a14
commit 2c15d26759
1 changed files with 1 additions and 0 deletions
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drivers/hwmon/max6697.c
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@@ -312,6 +312,7 @@ static ssize_t temp_store(struct device *dev,
return ret; return ret;
mutex_lock(&data->update_lock); mutex_lock(&data->update_lock);
temp = clamp_val(temp, -1000000, 1000000); /* prevent underflow */
temp = DIV_ROUND_CLOSEST(temp, 1000) + data->temp_offset; temp = DIV_ROUND_CLOSEST(temp, 1000) + data->temp_offset;
temp = clamp_val(temp, 0, data->type == max6581 ? 255 : 127); temp = clamp_val(temp, 0, data->type == max6581 ? 255 : 127);
data->temp[nr][index] = temp; data->temp[nr][index] = temp;