iio: chemical: vz89x: prevent corrupted buffer from being read

Signed-off-by: Matt Ranostay <mranostay@gmail.com>
Signed-off-by: Jonathan Cameron <jic23@kernel.org>

1 files changed, 6 insertions, 2 deletions

diff --git a/drivers/iio/chemical/vz89x.c b/drivers/iio/chemical/vz89x.c
index 289d2919deea..cd3870ead3fd 100644
--- a/drivers/iio/chemical/vz89x.c
+++ b/drivers/iio/chemical/vz89x.c
@@ -55,6 +55,7 @@ struct vz89x_data {
         struct mutex lock;
         int (*xfer)(struct vz89x_data *data, u8 cmd);
 
+        bool is_valid;
         unsigned long last_update;
         u8 buffer[VZ89TE_REG_MEASUREMENT_RD_SIZE];
 };
@@ -229,7 +230,10 @@ static int vz89x_get_measurement(struct vz89x_data *data)
 
         /* sensor can only be polled once a second max per datasheet */
         if (!time_after(jiffies, data->last_update + HZ))
-                return 0;
+                return data->is_valid ? 0 : -EAGAIN;
+
+        data->is_valid = false;
+        data->last_update = jiffies;
 
         ret = data->xfer(data, chip->cmd);
         if (ret < 0)
@@ -239,7 +243,7 @@ static int vz89x_get_measurement(struct vz89x_data *data)
         if (ret)
                 return -EAGAIN;
 
-        data->last_update = jiffies;
+        data->is_valid = true;
 
         return 0;
 }