| Message ID | 20200722155103.979802-14-jic23@kernel.org (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | IIO: Fused set 1 and 2 of timestamp alignment fixes | expand |
On Wed, 22 Jul 2020 16:50:49 +0100 Jonathan Cameron <jic23@kernel.org> wrote: > From: Jonathan Cameron <Jonathan.Cameron@huawei.com> > > 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. > > This data is allocated with kzalloc so no data can leak apart from > previous readings. > > The explicit alignment of ts is not necessary in this case as by > coincidence the padding will end up the same, however I consider > it to make the code less fragile and have included it. > > Fixes: bc11ca4a0b84 ("iio:magnetometer:ak8975: triggered buffer support") > Reported-by: Lars-Peter Clausen <lars@metafoo.de> > Cc: Gregor Boirie <gregor.boirie@parrot.com> > Cc: Andy Shevchenko <andriy.shevchenko@linux.intel.com> > Cc: Linus Walleij <linus.walleij@linaro.org> > Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com> Applied and marked for stable. Thanks, Jonathan > --- > drivers/iio/magnetometer/ak8975.c | 16 +++++++++++----- > 1 file changed, 11 insertions(+), 5 deletions(-) > > diff --git a/drivers/iio/magnetometer/ak8975.c b/drivers/iio/magnetometer/ak8975.c > index 03d71f796177..623766ff800b 100644 > --- a/drivers/iio/magnetometer/ak8975.c > +++ b/drivers/iio/magnetometer/ak8975.c > @@ -366,6 +366,12 @@ struct ak8975_data { > struct iio_mount_matrix orientation; > struct regulator *vdd; > struct regulator *vid; > + > + /* Ensure natural alignment of timestamp */ > + struct { > + s16 channels[3]; > + s64 ts __aligned(8); > + } scan; > }; > > /* Enable attached power regulator if any. */ > @@ -793,7 +799,6 @@ static void ak8975_fill_buffer(struct iio_dev *indio_dev) > const struct i2c_client *client = data->client; > const struct ak_def *def = data->def; > int ret; > - s16 buff[8]; /* 3 x 16 bits axis values + 1 aligned 64 bits timestamp */ > __le16 fval[3]; > > mutex_lock(&data->lock); > @@ -816,12 +821,13 @@ static void ak8975_fill_buffer(struct iio_dev *indio_dev) > mutex_unlock(&data->lock); > > /* Clamp to valid range. */ > - buff[0] = clamp_t(s16, le16_to_cpu(fval[0]), -def->range, def->range); > - buff[1] = clamp_t(s16, le16_to_cpu(fval[1]), -def->range, def->range); > - buff[2] = clamp_t(s16, le16_to_cpu(fval[2]), -def->range, def->range); > + data->scan.channels[0] = clamp_t(s16, le16_to_cpu(fval[0]), -def->range, def->range); > + data->scan.channels[1] = clamp_t(s16, le16_to_cpu(fval[1]), -def->range, def->range); > + data->scan.channels[2] = clamp_t(s16, le16_to_cpu(fval[2]), -def->range, def->range); > > - iio_push_to_buffers_with_timestamp(indio_dev, buff, > + iio_push_to_buffers_with_timestamp(indio_dev, &data->scan, > iio_get_time_ns(indio_dev)); > + > return; > > unlock:
diff --git a/drivers/iio/magnetometer/ak8975.c b/drivers/iio/magnetometer/ak8975.c index 03d71f796177..623766ff800b 100644 --- a/drivers/iio/magnetometer/ak8975.c +++ b/drivers/iio/magnetometer/ak8975.c @@ -366,6 +366,12 @@ struct ak8975_data { struct iio_mount_matrix orientation; struct regulator *vdd; struct regulator *vid; + + /* Ensure natural alignment of timestamp */ + struct { + s16 channels[3]; + s64 ts __aligned(8); + } scan; }; /* Enable attached power regulator if any. */ @@ -793,7 +799,6 @@ static void ak8975_fill_buffer(struct iio_dev *indio_dev) const struct i2c_client *client = data->client; const struct ak_def *def = data->def; int ret; - s16 buff[8]; /* 3 x 16 bits axis values + 1 aligned 64 bits timestamp */ __le16 fval[3]; mutex_lock(&data->lock); @@ -816,12 +821,13 @@ static void ak8975_fill_buffer(struct iio_dev *indio_dev) mutex_unlock(&data->lock); /* Clamp to valid range. */ - buff[0] = clamp_t(s16, le16_to_cpu(fval[0]), -def->range, def->range); - buff[1] = clamp_t(s16, le16_to_cpu(fval[1]), -def->range, def->range); - buff[2] = clamp_t(s16, le16_to_cpu(fval[2]), -def->range, def->range); + data->scan.channels[0] = clamp_t(s16, le16_to_cpu(fval[0]), -def->range, def->range); + data->scan.channels[1] = clamp_t(s16, le16_to_cpu(fval[1]), -def->range, def->range); + data->scan.channels[2] = clamp_t(s16, le16_to_cpu(fval[2]), -def->range, def->range); - iio_push_to_buffers_with_timestamp(indio_dev, buff, + iio_push_to_buffers_with_timestamp(indio_dev, &data->scan, iio_get_time_ns(indio_dev)); + return; unlock: