CVE-2025-40046

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.

Red Hat Enterprise Linux kernel packages are not vulnerable to this issue because the io_uring zero-copy network reception interface is not present in supported enterprise kernels. The vulnerability stems from recursive accounting errors when handling fragmented packets within zero-copy receive operations introduced in newer upstream kernels. As a result, this flaw poses no operational risk to supported Red Hat environments.