RE: [PATCH 3/3] spi: spi-mem: Add extra sanity checks on the op param

[Yogesh Narayan Gaur <yogeshnarayan.gaur@xxxxxxx>]

Hi Boris,

> -----Original Message-----
> From: linux-mtd [mailto:linux-mtd-bounces@xxxxxxxxxxxxxxxxxxx] On Behalf Of
> Boris Brezillon
> Sent: Thursday, September 20, 2018 1:01 PM
> To: Mark Brown <broonie@xxxxxxxxxx>; linux-spi@xxxxxxxxxxxxxxx
> Cc: Marek Vasut <marek.vasut@xxxxxxxxx>; Richard Weinberger
> <richard@xxxxxx>; Boris Brezillon <boris.brezillon@xxxxxxxxxxx>; linux-
> mtd@xxxxxxxxxxxxxxxxxxx; Brian Norris <computersforpeace@xxxxxxxxx>; David
> Woodhouse <dwmw2@xxxxxxxxxxxxx>
> Subject: [PATCH 3/3] spi: spi-mem: Add extra sanity checks on the op param
> 
> Some combinations are simply not valid and should be rejected before the op is
> passed to the SPI controller driver.
> 
> Add an spi_mem_check_op() helper and use it in spi_mem_exec_op() and
> spi_mem_supports_op() to make sure the spi-mem operation is valid.
> 
> Signed-off-by: Boris Brezillon <boris.brezillon@xxxxxxxxxxx>
> ---
>  drivers/spi/spi-mem.c | 54
> +++++++++++++++++++++++++++++++++++++++++++++------
>  1 file changed, 48 insertions(+), 6 deletions(-)
> 
> diff --git a/drivers/spi/spi-mem.c b/drivers/spi/spi-mem.c index
> eb72dba71d83..cc3d425aae56 100644
> --- a/drivers/spi/spi-mem.c
> +++ b/drivers/spi/spi-mem.c
> @@ -12,6 +12,8 @@
> 
>  #include "internals.h"
> 
> +#define SPI_MEM_MAX_BUSWIDTH		4
> +
>  /**
>   * spi_controller_dma_map_mem_op_data() - DMA-map the buffer attached to
> a
>   *					  memory operation
> @@ -149,6 +151,44 @@ static bool spi_mem_default_supports_op(struct
> spi_mem *mem,  }  EXPORT_SYMBOL_GPL(spi_mem_default_supports_op);
> 
> +static bool spi_mem_buswidth_is_valid(u8 buswidth) {
> +	if (hweight8(buswidth) > 1 || buswidth > SPI_MEM_MAX_BUSWIDTH)

Isn't check for lower limit should be '< 1'?

--
Regards
Yogesh Gaur

> +		return false;
> +
> +	return true;
> +}
> +
> +static int spi_mem_check_op(const struct spi_mem_op *op) {
> +	if (!op->cmd.buswidth)
> +		return -EINVAL;
> +
> +	if ((op->addr.nbytes && !op->addr.buswidth) ||
> +	    (op->dummy.nbytes && !op->dummy.buswidth) ||
> +	    (op->data.nbytes && !op->data.buswidth))
> +		return -EINVAL;
> +
> +	if (spi_mem_buswidth_is_valid(op->cmd.buswidth) ||
> +	    spi_mem_buswidth_is_valid(op->addr.buswidth) ||
> +	    spi_mem_buswidth_is_valid(op->dummy.buswidth) ||
> +	    spi_mem_buswidth_is_valid(op->data.buswidth))
> +		return -EINVAL;
> +
> +	return 0;
> +}
> +
> +static bool spi_mem_internal_supports_op(struct spi_mem *mem,
> +					 const struct spi_mem_op *op)
> +{
> +	struct spi_controller *ctlr = mem->spi->controller;
> +
> +	if (ctlr->mem_ops && ctlr->mem_ops->supports_op)
> +		return ctlr->mem_ops->supports_op(mem, op);
> +
> +	return spi_mem_default_supports_op(mem, op); }
> +
>  /**
>   * spi_mem_supports_op() - Check if a memory device and the controller it is
>   *			   connected to support a specific memory operation
> @@ -166,12 +206,10 @@
> EXPORT_SYMBOL_GPL(spi_mem_default_supports_op);
>   */
>  bool spi_mem_supports_op(struct spi_mem *mem, const struct spi_mem_op
> *op)  {
> -	struct spi_controller *ctlr = mem->spi->controller;
> -
> -	if (ctlr->mem_ops && ctlr->mem_ops->supports_op)
> -		return ctlr->mem_ops->supports_op(mem, op);
> +	if (spi_mem_check_op(op))
> +		return false;
> 
> -	return spi_mem_default_supports_op(mem, op);
> +	return spi_mem_internal_supports_op(mem, op);
>  }
>  EXPORT_SYMBOL_GPL(spi_mem_supports_op);
> 
> @@ -196,7 +234,11 @@ int spi_mem_exec_op(struct spi_mem *mem, const
> struct spi_mem_op *op)
>  	u8 *tmpbuf;
>  	int ret;
> 
> -	if (!spi_mem_supports_op(mem, op))
> +	ret = spi_mem_check_op(op);
> +	if (ret)
> +		return ret;
> +
> +	if (!spi_mem_internal_supports_op(mem, op))
>  		return -ENOTSUPP;
> 
>  	if (ctlr->mem_ops) {
> --
> 2.14.1
> 
> 
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