io_uring/zcrx: fix overshooting recv limit

Vulnerability Description

In the Linux kernel, the following vulnerability has been resolved: io_uring/zcrx: fix overshooting recv limit It's reported that sometimes a zcrx request can receive more than was requested. It's caused by io_zcrx_recv_skb() adjusting desc->count for all received buffers including frag lists, but then doing recursive calls to process frag list skbs, which leads to desc->count double accounting and underflow.

References

• https://git.kernel.org/stable/c/8bcc9eaf1b19f1a7029cba19f6bd4122b40f6c4f
• https://git.kernel.org/stable/c/09cfd3c52ea76f43b3cb15e570aeddf633d65e80