CVE-2025-38465

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

netlink: Fix wraparounds of sk->skrmemalloc.

Netlink has this pattern in some places

if (atomicread(&sk->skrmemalloc) > sk->skrcvbuf) atomicadd(skb->truesize, &sk->skrmem_alloc);

, which has the same problem fixed by commit 5a465a0da13e ("udp: Fix multiple wraparounds of sk->skrmemalloc.").

For example, if we set INTMAX to SORCVBUFFORCE, the condition is always false as the two operands are of int.

Then, a single socket can eat as many skb as possible until OOM happens, and we can see multiple wraparounds of sk->skrmemalloc.

Let's fix it by using atomicaddreturn() and comparing the two variables as unsigned int.

Before: [root@fedora ~]# ss -f netlink Recv-Q Send-Q Local Address:Port Peer Address:Port -1668710080 0 rtnl:nl_wraparound/293 *

After: [root@fedora ~]# ss -f netlink Recv-Q Send-Q Local Address:Port Peer Address:Port 2147483072 0 rtnl:nlwraparound/290 * ^ `--- INTMAX - 576