From: Jonathan Cameron Jonathan.Cameron@huawei.com
commit eb1a148ef41d8ae8d9201efc3f1b145976290331 upstream.
One of a class of bugs pointed out by Lars in a recent review. iio_push_to_buffers_with_timestamp assumes the buffer used is aligned to the size of the timestamp (8 bytes). This is not guaranteed in this driver which uses an array of smaller elements on the stack. As Lars also noted this anti pattern can involve a leak of data to userspace and that indeed can happen here. We close both issues by moving to a suitable structure in the iio_priv() data with alignment explicitly requested. This data is allocated with kzalloc so no data can leak appart from previous readings.
The explicit alignment of ts is necessary to ensure consistent padding for x86_32 in which the ts would otherwise be 4 byte aligned.
Fixes: 283d26917ad6 ("iio: chemical: ccs811: Add triggered buffer support") Reported-by: Lars-Peter Clausen lars@metafoo.de Cc: Narcisa Ana Maria Vasile narcisaanamaria12@gmail.com Signed-off-by: Jonathan Cameron Jonathan.Cameron@huawei.com Reviewed-by: Andy Shevchenko andy.shevchenko@gmail.com Cc: Stable@vger.kernel.org Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org
--- drivers/iio/chemical/ccs811.c | 13 +++++++++---- 1 file changed, 9 insertions(+), 4 deletions(-)
--- a/drivers/iio/chemical/ccs811.c +++ b/drivers/iio/chemical/ccs811.c @@ -73,6 +73,11 @@ struct ccs811_data { struct i2c_client *client; struct mutex lock; /* Protect readings */ struct ccs811_reading buffer; + /* Ensures correct alignment of timestamp if present */ + struct { + s16 channels[2]; + s64 ts __aligned(8); + } scan; };
static const struct iio_chan_spec ccs811_channels[] = { @@ -275,17 +280,17 @@ static irqreturn_t ccs811_trigger_handle struct iio_dev *indio_dev = pf->indio_dev; struct ccs811_data *data = iio_priv(indio_dev); struct i2c_client *client = data->client; - s16 buf[8]; /* s16 eCO2 + s16 TVOC + padding + 8 byte timestamp */ int ret;
- ret = i2c_smbus_read_i2c_block_data(client, CCS811_ALG_RESULT_DATA, 4, - (u8 *)&buf); + ret = i2c_smbus_read_i2c_block_data(client, CCS811_ALG_RESULT_DATA, + sizeof(data->scan.channels), + (u8 *)data->scan.channels); if (ret != 4) { dev_err(&client->dev, "cannot read sensor data\n"); goto err; }
- iio_push_to_buffers_with_timestamp(indio_dev, buf, + iio_push_to_buffers_with_timestamp(indio_dev, &data->scan, iio_get_time_ns(indio_dev));
err: