Re: [PATCH v3 1/2] iio: imu: st_lsm6dsx: fix possible lockup in st_lsm6dsx_read_fifo

[Jonathan Cameron <jic23@kernel.org>]

On Tue, 11 Mar 2025 09:49:47 +0100
Silvano Seva <s.seva@4sigma.it> wrote:

> Prevent st_lsm6dsx_read_fifo from falling in an infinite loop in case
> pattern_len is equal to zero and the device FIFO is not empty.
> 
> Fixes: 290a6ce11d93 ("iio: imu: add support to lsm6dsx driver")
> Signed-off-by: Silvano Seva <s.seva@4sigma.it>
I think you could validly have kept Lorenzo's ack given this was
just breaking the patch into two parts. I put it back and applied
these with them marked for stable to the fixes-togreg branch of iio.git

Thanks,

Jonathan

> ---
> 
> Changes since v1:
> * st_lsm6dsx_read_fifo: moved check for zero pattern_len before fifo_len assignment
> * st_lsm6dsx_read_fifo: dropped check for zero fifo_len
> * added Fixes tags in commit message
> 
> Changes since v2:
> * split patch in two parts, one fixing st_lsm6dsx_read_fifo and one fixing
> st_lsm6dsx_read_tagged_fifo
> 
>  drivers/iio/imu/st_lsm6dsx/st_lsm6dsx_buffer.c | 3 +++
>  1 file changed, 3 insertions(+)
> 
> diff --git a/drivers/iio/imu/st_lsm6dsx/st_lsm6dsx_buffer.c b/drivers/iio/imu/st_lsm6dsx/st_lsm6dsx_buffer.c
> index 0a7cd8c1aa33..480a9b31065c 100644
> --- a/drivers/iio/imu/st_lsm6dsx/st_lsm6dsx_buffer.c
> +++ b/drivers/iio/imu/st_lsm6dsx/st_lsm6dsx_buffer.c
> @@ -392,6 +392,9 @@ int st_lsm6dsx_read_fifo(struct st_lsm6dsx_hw *hw)
>  	if (fifo_status & cpu_to_le16(ST_LSM6DSX_FIFO_EMPTY_MASK))
>  		return 0;
>  
> +	if (!pattern_len)
> +		pattern_len = ST_LSM6DSX_SAMPLE_SIZE;
> +
>  	fifo_len = (le16_to_cpu(fifo_status) & fifo_diff_mask) *
>  		   ST_LSM6DSX_CHAN_SIZE;
>  	fifo_len = (fifo_len / pattern_len) * pattern_len;