Hi Dan,
Thanks for reaching out. I do have the same question before. If I
remember it correctly, the 'chan' is returned by to_sf_pdma_chan()
which contains 'dchan'. 'chan' s unlikely to be NULL since it's
container.
I agreed that the code logic causes confused easily. Now the driver is
in -next branch. I can check with maintainer where/when to fix it.
--
Green
On Sat, Nov 16, 2019 at 4:23 PM Dan Carpenter <dan.carpenter@xxxxxxxxxx> wrote:
>
> Hello Green Wan,
>
> This is a semi-automatic email about new static checker warnings.
>
> The patch 6973886ad58e: "dmaengine: sf-pdma: add platform DMA support
> for HiFive Unleashed A00" from Nov 7, 2019, leads to the following
> Smatch complaint:
>
> drivers/dma/sf-pdma/sf-pdma.c:103 sf_pdma_prep_dma_memcpy()
> error: we previously assumed 'chan' could be null (see line 97)
>
> drivers/dma/sf-pdma/sf-pdma.c
> 96
> 97 if (chan && (!len || !dest || !src)) {
> ^^^^
> Check for NULL
>
> 98 dev_err(chan->pdma->dma_dev.dev,
> 99 "Please check dma len, dest, src!\n");
> 100 return NULL;
> 101 }
> 102
> 103 desc = sf_pdma_alloc_desc(chan);
> ^^^^
> Unchecked dereference inside the function.
>
> 104 if (!desc)
> 105 return NULL;
>
> regards,
> dan carpenter
