Re: [PATCH v2] iio: adc: ad7923: Fix buffer overflow for tx_buf and ring_xfer

[Nuno Sá]

On Tue, 2024-10-29 at 13:46 +0000, Zicheng Qu wrote:
> The AD7923 was updated to support devices with 8 channels, but the size
> of tx_buf and ring_xfer was not increased accordingly, leading to a
> potential buffer overflow in ad7923_update_scan_mode().
> 
> Fixes: 851644a60d20 ("iio: adc: ad7923: Add support for the ad7908/ad7918/ad7928")
> Cc: <stable@xxxxxxxxxxxxxxx>
> Signed-off-by: Nuno Sá <noname.nuno@xxxxxxxxx>
> Signed-off-by: Zicheng Qu <quzicheng@xxxxxxxxxx>
> ---

Reviewed-by: Nuno Sa <nuno.sa@xxxxxxxxxx>

> v2:
> - Fixed: Addressed buffer overflow in ad7923_update_scan_mode() due to 
> insufficient tx_buf and ring_xfer size for 8-channel devices.
> - Issue: Original patch attempted to fix the overflow by limiting the 
> length, but did not address the root cause of buffer size mismatch.
> - Solution: Increased tx_buf and ring_xfer sizes recommended by Nuno to 
> support all 8 channels, ensuring adequate buffer capacity.
> - Previous patch link: 
> https://lore.kernel.org/linux-iio/20241028142357.1032380-1-quzicheng@xxxxxxxxxx/T/#u
>  drivers/iio/adc/ad7923.c | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/iio/adc/ad7923.c b/drivers/iio/adc/ad7923.c
> index 09680015a7ab..acc44cb34f82 100644
> --- a/drivers/iio/adc/ad7923.c
> +++ b/drivers/iio/adc/ad7923.c
> @@ -48,7 +48,7 @@
>  
>  struct ad7923_state {
>  	struct spi_device		*spi;
> -	struct spi_transfer		ring_xfer[5];
> +	struct spi_transfer		ring_xfer[9];
>  	struct spi_transfer		scan_single_xfer[2];
>  	struct spi_message		ring_msg;
>  	struct spi_message		scan_single_msg;
> @@ -64,7 +64,7 @@ struct ad7923_state {
>  	 * Length = 8 channels + 4 extra for 8 byte timestamp
>  	 */
>  	__be16				rx_buf[12] __aligned(IIO_DMA_MINALIGN);
> -	__be16				tx_buf[4];
> +	__be16				tx_buf[8];
>  };
>  
>  struct ad7923_chip_info {