CVE-2022-49320: 
Linux Kernel vulnerability analysis and mitigation

CVE-2022-49320 affects the Linux kernel's DMA engine, specifically in the zynqmp_dma driver. The vulnerability was discovered in the struct zynqmp_dma_chan where the desc_size data type could potentially cause an overflow condition in 32-bit multiplication operations (Kernel Commit).

The vulnerability exists in the zynqmp_dma_alloc/free_chan_resources functions where there is a potential overflow in expressions using desc_size and ZYNQMP_DMA_NUM_DESCS arguments, which were both 32-bit values. The issue occurs in operations like: dma_alloc_coherent(chan->dev, (2 * chan->desc_size * ZYNQMP_DMA_NUM_DESCS), &chan->desc_pool_p, GFP_KERNEL) and dma_free_coherent(chan->dev,(2 * ZYNQMP_DMA_DESC_SIZE(chan) * ZYNQMP_DMA_NUM_DESCS), chan->desc_pool_v, chan->desc_pool_p) (Kernel Commit).

While the overflow condition had not been observed in practice, it presented a potential security risk in cases involving 32-bit multiplication operations in the DMA engine (Kernel Commit).

The issue was fixed by changing the desc_size data type from u32 to size_t in the struct zynqmp_dma_chan. Additionally, the fix included reusing the ZYNQMP_DMA_DESC_SIZE macro in the dma_alloc_coherent API argument (Kernel Commit).