CVE-2025-21852 — NULL Pointer Dereference in Linux

In the Linux kernel, the following vulnerability has been resolved: net: Add rx_skb of kfree_skb to raw_tp_null_args[]. Yan Zhai reported a BPF prog could trigger a null-ptr-deref [0] in trace_kfree_skb if the prog does not check if rx_sk is NULL. Commit c53795d48ee8 ("net: add rx_sk to trace_kfree_skb") added rx_sk to trace_kfree_skb, but rx_sk is optional and could be NULL. Let's add kfree_skb to raw_tp_null_args[] to let the BPF verifier validate such a prog and prevent the issue. Now we…