Re: [PATCH] dma-buf: return -EINVAL if dmabuf object is NULL

["Christian König" <christian.koenig@amd.com>]

To be honest I think the if(WARN_ON(!dmabuf)) return -EINVAL handling 
here is misleading in the first place.

Returning -EINVAL on a hard coding error is not good practice and should 
probably be removed from the DMA-buf subsystem in general.

Christian.

Am 18.08.21 um 13:58 schrieb Nuno Sá:
> On top of warning about a NULL object, we also want to return with a
> proper error code (as done in 'dma_buf_begin_cpu_access()'). Otherwise,
> we will get a NULL pointer dereference.
>
> Fixes: fc13020e086b ("dma-buf: add support for kernel cpu access")
> Signed-off-by: Nuno Sá <nuno.sa@analog.com>
> ---
>   drivers/dma-buf/dma-buf.c | 3 ++-
>   1 file changed, 2 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/dma-buf/dma-buf.c b/drivers/dma-buf/dma-buf.c
> index 63d32261b63f..8ec7876dd523 100644
> --- a/drivers/dma-buf/dma-buf.c
> +++ b/drivers/dma-buf/dma-buf.c
> @@ -1231,7 +1231,8 @@ int dma_buf_end_cpu_access(struct dma_buf *dmabuf,
>   {
>   	int ret = 0;
>   
> -	WARN_ON(!dmabuf);
> +	if (WARN_ON(!dmabuf))
> +		return -EINVAL;
>   
>   	might_lock(&dmabuf->resv->lock.base);
>