iio: light: Add check for array bounds in veml6075_read_int_time_ms

The array contains only 5 elements, but the index calculated by
veml6075_read_int_time_index can range from 0 to 7,
which could lead to out-of-bounds access. The check prevents this issue.

Coverity Issue
CID 1574309: (#1 of 1): Out-of-bounds read (OVERRUN)
overrun-local: Overrunning array veml6075_it_ms of 5 4-byte
elements at element index 7 (byte offset 31) using
index int_index (which evaluates to 7)

This is hardening against potentially broken hardware. Good to have
but not necessary to backport.

Fixes: 3b82f43238ae ("iio: light: add VEML6075 UVA and UVB light sensor driver")
Signed-off-by: Karan Sanghavi <karansanghvi98@gmail.com>
Reviewed-by: Javier Carrasco <javier.carrasco.cruz@gmail.com>
Link: https://patch.msgid.link/Z7dnrEpKQdRZ2qFU@Emma
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>

diff --git a/drivers/iio/light/veml6075.c b/drivers/iio/light/veml6075.c
index 05d4c0e9015d6e4be8934e030a911badc4c89189..859891e8f115217819ce1d3ebbc50032745aa63a 100644 (file)
--- a/drivers/iio/light/veml6075.c
+++ b/drivers/iio/light/veml6075.c
@@ -195,13 +195,17 @@ static int veml6075_read_uv_direct(struct veml6075_data *data, int chan,
 
 static int veml6075_read_int_time_index(struct veml6075_data *data)
 {
-       int ret, conf;
+       int ret, conf, int_index;
 
        ret = regmap_read(data->regmap, VEML6075_CMD_CONF, &conf);
        if (ret < 0)
                return ret;
 
-       return FIELD_GET(VEML6075_CONF_IT, conf);
+       int_index = FIELD_GET(VEML6075_CONF_IT, conf);
+       if (int_index >= ARRAY_SIZE(veml6075_it_ms))
+               return -EINVAL;
+
+       return int_index;
 }
 
 static int veml6075_read_int_time_ms(struct veml6075_data *data, int *val)