iio: chemical: bme680: Fix overflows in compensate() functions

commit fdd478c3ae98c3f13628e110dce9b6cfb0d9b3c8 upstream.

There are cases in the compensate functions of the driver that
there could be overflows of variables due to bit shifting ops.
These implications were initially discussed here [1] and they
were mentioned in log message of Commit 1b3bd8592780 ("iio:
chemical: Add support for Bosch BME680 sensor").

[1]: https://lore.kernel.org/linux-iio/20180728114028.3c1bbe81@archlinux/

Fixes: 1b3bd8592780 ("iio: chemical: Add support for Bosch BME680 sensor")
Signed-off-by: Vasileios Amoiridis <vassilisamir@gmail.com>
Link: https://lore.kernel.org/r/20240606212313.207550-4-vassilisamir@gmail.com
Cc: <Stable@vger.kernel.org>
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/iio/chemical/bme680_core.c b/drivers/iio/chemical/bme680_core.c
index 178d1b72ce43085ef507ead956553269232af54f..2f8c51654ee0d45b8c9679524b68f26aa6cf55eb 100644 (file)
--- a/drivers/iio/chemical/bme680_core.c
+++ b/drivers/iio/chemical/bme680_core.c
@@ -334,10 +334,10 @@ static s16 bme680_compensate_temp(struct bme680_data *data,
        if (!calib->par_t2)
                bme680_read_calib(data, calib);
 
-       var1 = (adc_temp >> 3) - (calib->par_t1 << 1);
+       var1 = (adc_temp >> 3) - ((s32)calib->par_t1 << 1);
        var2 = (var1 * calib->par_t2) >> 11;
        var3 = ((var1 >> 1) * (var1 >> 1)) >> 12;
-       var3 = (var3 * (calib->par_t3 << 4)) >> 14;
+       var3 = (var3 * ((s32)calib->par_t3 << 4)) >> 14;
        data->t_fine = var2 + var3;
        calc_temp = (data->t_fine * 5 + 128) >> 8;
 
@@ -360,9 +360,9 @@ static u32 bme680_compensate_press(struct bme680_data *data,
        var1 = (data->t_fine >> 1) - 64000;
        var2 = ((((var1 >> 2) * (var1 >> 2)) >> 11) * calib->par_p6) >> 2;
        var2 = var2 + (var1 * calib->par_p5 << 1);
-       var2 = (var2 >> 2) + (calib->par_p4 << 16);
+       var2 = (var2 >> 2) + ((s32)calib->par_p4 << 16);
        var1 = (((((var1 >> 2) * (var1 >> 2)) >> 13) *
-                       (calib->par_p3 << 5)) >> 3) +
+                       ((s32)calib->par_p3 << 5)) >> 3) +
                        ((calib->par_p2 * var1) >> 1);
        var1 = var1 >> 18;
        var1 = ((32768 + var1) * calib->par_p1) >> 15;
@@ -380,7 +380,7 @@ static u32 bme680_compensate_press(struct bme680_data *data,
        var3 = ((press_comp >> 8) * (press_comp >> 8) *
                        (press_comp >> 8) * calib->par_p10) >> 17;
 
-       press_comp += (var1 + var2 + var3 + (calib->par_p7 << 7)) >> 4;
+       press_comp += (var1 + var2 + var3 + ((s32)calib->par_p7 << 7)) >> 4;
 
        return press_comp;
 }
@@ -406,7 +406,7 @@ static u32 bme680_compensate_humid(struct bme680_data *data,
                 (((temp_scaled * ((temp_scaled * calib->par_h5) / 100))
                   >> 6) / 100) + (1 << 14))) >> 10;
        var3 = var1 * var2;
-       var4 = calib->par_h6 << 7;
+       var4 = (s32)calib->par_h6 << 7;
        var4 = (var4 + ((temp_scaled * calib->par_h7) / 100)) >> 4;
        var5 = ((var3 >> 14) * (var3 >> 14)) >> 10;
        var6 = (var4 * var5) >> 1;