[PATCH 5.4 026/100] iio: imu: st_lsm6dsx: Avoid potential array overflow in st_lsm6dsx_set_odr()

[Greg Kroah-Hartman]

From: Teng Qi <starmiku1207184332@xxxxxxxxx>

[ Upstream commit 94be878c882d8d784ff44c639bf55f3b029f85af ]

The length of hw->settings->odr_table is 2 and ref_sensor->id is an enum
variable whose value is between 0 and 5.
However, the value ST_LSM6DSX_ID_MAX (i.e. 5) is not caught properly in
 switch (sensor->id) {

If ref_sensor->id is ST_LSM6DSX_ID_MAX, an array overflow will ocurrs in
function st_lsm6dsx_check_odr():
  odr_table = &sensor->hw->settings->odr_table[sensor->id];

and in function st_lsm6dsx_set_odr():
  reg = &hw->settings->odr_table[ref_sensor->id].reg;

To avoid this array overflow, handle ST_LSM6DSX_ID_GYRO explicitly and
return -EINVAL for the default case.

The enum value ST_LSM6DSX_ID_MAX is only present as an easy way to check
the limit and as such is never used, however this is not locally obvious.

Reported-by: TOTE Robot <oslab@xxxxxxxxxxxxxxx>
Signed-off-by: Teng Qi <starmiku1207184332@xxxxxxxxx>
Acked-by: Lorenzo Bianconi <lorenzo@xxxxxxxxxx>
Link: https://lore.kernel.org/r/20211011114003.976221-1-starmiku1207184332@xxxxxxxxx
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@xxxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
---
 drivers/iio/imu/st_lsm6dsx/st_lsm6dsx_core.c | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/drivers/iio/imu/st_lsm6dsx/st_lsm6dsx_core.c b/drivers/iio/imu/st_lsm6dsx/st_lsm6dsx_core.c
index 057a4b0100106..8850da8e25d69 100644
--- a/drivers/iio/imu/st_lsm6dsx/st_lsm6dsx_core.c
+++ b/drivers/iio/imu/st_lsm6dsx/st_lsm6dsx_core.c
@@ -1015,6 +1015,8 @@ static int st_lsm6dsx_set_odr(struct st_lsm6dsx_sensor *sensor, u16 req_odr)
 	int err;
 
 	switch (sensor->id) {
+	case ST_LSM6DSX_ID_GYRO:
+		break;
 	case ST_LSM6DSX_ID_EXT0:
 	case ST_LSM6DSX_ID_EXT1:
 	case ST_LSM6DSX_ID_EXT2:
@@ -1040,8 +1042,8 @@ static int st_lsm6dsx_set_odr(struct st_lsm6dsx_sensor *sensor, u16 req_odr)
 		}
 		break;
 	}
-	default:
-		break;
+	default: /* should never occur */
+		return -EINVAL;
 	}
 
 	if (req_odr > 0) {
-- 
2.33.0