net: libwx: fix the using of Rx buffer DMA

Vulnerability Description

In the Linux kernel, the following vulnerability has been resolved: net: libwx: fix the using of Rx buffer DMA The wx_rx_buffer structure contained two DMA address fields: 'dma' and 'page_dma'. However, only 'page_dma' was actually initialized and used to program the Rx descriptor. But 'dma' was uninitialized and used in some paths. This could lead to undefined behavior, including DMA errors or use-after-free, if the uninitialized 'dma' was used. Althrough such error has not yet occurred, it is worth fixing in the code.

References

• https://git.kernel.org/stable/c/027701180a7bcb64c42eab291133ef0c87b5b6c5
• https://git.kernel.org/stable/c/ba7c793f96c1c2b944bb6f423d7243f3afc30fe9
• https://git.kernel.org/stable/c/05c37b574997892a40a0e9b9b88a481566b2367d
• https://git.kernel.org/stable/c/5fd77cc6bd9b368431a815a780e407b7781bcca0