CVE-2022-49320: Integer Overflow or Wraparound

In the Linux kernel, the following vulnerability has been resolved:

dmaengine: zynqmp_dma: In struct zynqmp_dma_chan fix desc_size data type

In zynqmp_dma_alloc/free_chan_resources functions there is a potential overflow in the below expressions.

dma_alloc_coherent(chan->dev, (2 * chan->desc_size * ZYNQMP_DMA_NUM_DESCS), &chan->desc_pool_p, GFP_KERNEL);

dma_free_coherent(chan->dev,(2 * ZYNQMP_DMA_DESC_SIZE(chan) * ZYNQMP_DMA_NUM_DESCS), chan->desc_pool_v, chan->desc_pool_p);

The arguments desc_size and ZYNQMP_DMA_NUM_DESCS were 32 bit. Though this overflow condition is not observed but it is a potential problem in the case of 32-bit multiplication. Hence fix it by changing the desc_size data type to size_t.

In addition to coverity fix it also reuse ZYNQMP_DMA_DESC_SIZE macro in dma_alloc_coherent API argument.

Addresses-Coverity: Event overflow_before_widen.